DE102020115734A1 - Device, system and method for investigating the flow around turbine blades with supersonic flow - Google Patents

Abstract

In order to simplify the investigation of the flow around turbine blades with supersonic outflow, a device for investigating the flow around turbine blades with supersonic outflow, which device has a first flow path between a fluid inlet and a fluid outlet, wherein in the first flow path between the fluid inlet and the Fluid outlet a profile body cascade with a plurality of profile bodies is arranged, wherein adjacent profile bodies are spaced from one another and define a profile flow path section between them, wherein the first flow path between the fluid inlet and the profile body cascade defines a flow path inlet section and between the profile body cascade and the fluid outlet defines a flow path outlet section and wherein the flow path outlet section is bounded by a fluid-permeable separating element, wherein the device has a second flow path with an inlet and an outlet wherein the second flow path is separated from the flow path outlet section by the separating element, the device having a secondary flow path, the secondary flow path connecting the flow path inlet section and the second flow path in a fluid-effective manner to one another, the secondary flow path delimiting the first profile body which is farthest from the fluid outlet and wherein the secondary flow path defines a secondary flow path outlet direction into the second flow path that runs parallel or substantially parallel to the separating element. Furthermore, an improved system and an improved method for investigating the flow around turbine blades with supersonic discharge are proposed.

Description

The present invention relates to a device for examining the flow around turbine blades with supersonic outflow, which device has a first flow path between a fluid inlet and a fluid outlet, a profile body cascade with a plurality of profile bodies being arranged in the first flow path between the fluid inlet and the fluid outlet, wherein adjacent profile bodies are spaced from one another and define a profile flow path section between them, wherein the first flow path between the fluid inlet and the profile body cascade defines a flow path inlet section and between the profile body cascade and the fluid outlet defines a flow path outlet section, and wherein the flow path outlet section is delimited by a fluid-permeable separating element.

The present invention also relates to a system for examining the flow around turbine blades with supersonic outflow.

The present invention also relates to a method for examining the flow around turbine blades with supersonic outflow, in which method a first fluid flow is generated through a first flow path between a fluid inlet and a fluid outlet, a profile body cascade with in the first flow path between the fluid inlet and the fluid outlet a plurality of profile bodies is arranged, wherein adjacent profile bodies are arranged spaced from one another and define a profile flow path section between them, wherein the first flow path between the fluid inlet and the profile body cascade defines a flow path inlet section and between the profile body cascade and the fluid outlet defines a flow path outlet section, the flow path outlet section being a fluid-permeable one Separating element is limited.

It is known to use devices and systems of the type described at the outset in order to examine the flow around turbine blades of turbine stages with a supersonic outflow or of compressor stages in a compressor. Such cascade tests simulate the flow around or through a series of profiles of the turbine stages or the compressor stages, which differ only slightly from one another in terms of their shape, by means of a model-like device of the type described above.

With the known devices and methods, in particular, compression shocks in the outflow are investigated, which are an important part of cascade studies with supersonic components, since these compression shocks are decisive for the efficiency and the operating behavior of turbine stages.

A linear profile body cascade consists of a finite number of profile bodies which correspond in the profiles of the turbine blades, and accordingly the profile body cascade must have some kind of termination that represents a boundary condition for the flow. This termination is formed by the separating element. As a result, however, the outflow away from the profile body cascade is given a flow angle which is not necessarily identical to the outflow in a turbine stage. Compression shocks occurring in the flow are reflected on the separating element and thus falsify the measurements and observations.

Alternative devices that are used, however, do not have a separating element as a closure, but allow the outflow to expand into a free space at its end. However, the shape or shape of this space and its precise pressure conditions are decisive for the degree of expansion. It should also be taken into account that such a boundary condition also reflects shock waves and thus falsifies measurements and observations. Only with a very large number of profile bodies does the distance between the flow exit from the profile body cascade and the given boundary condition become so great that the strength of the reflected compression shocks due to diffusion is significantly reduced. However, a large number of profile bodies leads to a very high outlay in the manufacture of the device and in the provision of the fluid flow required for the investigations.

It should also be taken into account that a numerical check of the device results in the problem that a boundary of the profile body cascade at the flow outlet is neither completely an inflow nor an outflow. Correct numerical modeling of such boundary conditions is therefore difficult.

In principle, it would be possible to investigate full blade rings of turbines in which the problems of the boundary conditions described above do not occur, since the turbine blades form a closed circle. However, a large number of turbine blades are also necessary in this case. In addition, the curvature makes the use of imaging methods to examine the flows very difficult. For example, the so-called Schlieren technique for imaging can only be implemented with great effort.

It is therefore an object of the present invention to improve a device, a system and a method of the type described at the outset in such a way that the investigation of the flow around turbine blades with a supersonic outflow is simplified.

This object is achieved according to the invention in a device of the type described at the outset in that the device has a second flow path with an inlet and an outlet, that the second flow path is separated from the flow path outlet section by the separating element, that the device has a secondary flow path, that the secondary flow path the flow path inlet section and the second flow path fluid-effectively connects with each other, that the secondary flow path is delimited by the first profile body, which is furthest away from the fluid outlet, and that the secondary flow path defines a secondary flow path outlet direction into the second flow path that runs parallel or substantially parallel to the separating element.

Developing a device of the type described at the beginning in the proposed manner has the particular advantage that, despite the use of the separating element, a flow situation can be realized in which the outflow of the fluid flow through the profile body cascade corresponds to the flow through a row of blades or a circular cascade and thus the flow through an infinite one Cascade comes very close to the free space. The profile body cascade is also referred to below as a blade cascade or turbine blade cascade. A row of blades is, in particular, a complete ring of blades in a turbine or a compressor. A circular cascade corresponds in principle to a row of blades, but is part of a test bench and not part of a turbo machine. The second flow path runs in particular parallel or essentially parallel to the outflow direction of the fluid flow away from the profile body cascade. In particular, the same pressure, for example atmospheric pressure, can be present at the inlet and the outlet of the second flow path. Because part of the fluid flow flowing through the first flow path is directed through the secondary flow path, suction is created in the second flow path away from the separating element and into the second flow path. The outflow from the profile body cascade entrains a subsonic fluid flow from the second flow path to an outlet of the profile body cascade. In particular, if the separating element is designed to be fluid-permeable, the reflection of compression surges in the outflow of the profile body cascade on the separating element can be prevented by a local excess fluid being diverted through the separating element into the second flow path. In particular, a precise definition of the boundary conditions is thus possible. In this way, there is no additional effort, which arises from a side space, however designed, in which a pressure has to be controlled and / or regulated in a defined manner. With an optimal arrangement of the separating element and its design, pressure conditions similar to those of a free expansion, i.e. an expansion of the outflow into a free, unlimited space, can thus be created in particular on a surface of the separating element facing the profile body cascade. In known devices, it has hitherto been necessary to control the pressure in the side space separated by the separating element opposite the flow path outlet section in order to achieve an effective shock reduction without unduly disturbing the flow to be observed. In other words, the formation of the proposed secondary flow path and its alignment make it possible to avoid pressure control in the space delimited by the separating element with a side surface facing away from the profile body cascade. This simplifies the structure of the device. The execution of the examinations is also simplified.

It is favorable if a side surface of the first profile body facing away from the fluid inlet delimits the second flow path. This remote side surface, also referred to as the suction side of the profile body, makes it possible to direct the fluid flow through the secondary flow path in such a way that a suction effect occurs in the second flow path, which enables a passage of part of the fluid flow flowing through the flow path outlet section through the separating element and, if necessary, back In order to come as close as possible to the boundary condition of an expansion of the outflow away from the profile body cascade into a free space. In addition, the design of the device is simplified by the design.

In order to be able to observe a flow through the device in a simple manner, it is advantageous if the first flow path and the second flow path are formed between wall surfaces facing one another. In particular, the wall surfaces can run parallel to one another. The wall surfaces can optionally have windows through which the flow can be observed, for example in order to record flow images with Schlieren technology.

A simple construction of the device can in particular be achieved in that the Separating element is aligned transversely to the wall surfaces. Optionally, the separating element is aligned perpendicular to the wall surfaces. Arranging the separating element between the wall surfaces in the manner described enables a separation between the second flow path and the flow path outlet section in the desired manner.

For a simple observation of a fluid flow flowing through the device, it is advantageous if the wall surfaces are defined by side surfaces in the visible spectral range of transparent plates. The plates can in particular be plastic plates or glass plates. Such a configuration makes it possible, in particular, to fully observe a fluid flow in the first flow path and in the second flow path.

It is favorable if the separating element is arranged adjoining a profile body end of the first profile body pointing in the direction of the fluid outlet. In particular, a simple separation between the fluid flow in the second flow path and in the flow path outlet section can thus be achieved. The only connection between the first and second flow path is thus realized by the secondary flow path. The separating element, if it is designed to be fluid-permeable, does not form a flow path in the actual sense, but merely serves as a device to prevent the reflection of compression surges, as already explained above, by diverting a local excess of fluid through the separating element into the second flow path.

According to a further preferred embodiment of the invention it can be provided that an inlet direction of the fluid inlet and an outlet direction of the fluid outlet enclose a deflection angle. This can be in a range from 0 ° to 180 °. For example, the deflection angle can be 105 °. The deflection angle is predetermined by the profile bodies of the profile body cascade at which the fluid flow flowing through the flow path inlet section is deflected into the flow path outlet section.

A simple structure of the device results in particular from the fact that the outlet direction is defined by or essentially by an alignment of the profile body side surfaces of the profile body facing away from the fluid inlet relative to the inlet direction. The profile body side surfaces facing away form suction sides of the profile bodies, the suction sides of the profile bodies each extending from a center point of a front edge pointing counter to the flow direction to a center point of a rear edge of the profile bodies pointing in the flow direction.

The profile bodies can be designed in a simple manner if the profile body side surfaces facing away from the fluid inlet are flat or essentially flat.

It is advantageous if the separating element is arranged to run parallel or essentially parallel to the outlet direction. In this way, a lower flow resistance is achieved through the separating element. Furthermore, supersonic flows parallel to the wall as well as supersonic flows with only a low proportion of speed towards the wall are made possible. No flow angle is therefore predetermined by the separating element itself.

The device can be designed in a particularly simple manner if the second flow path defines a flow direction which runs in a straight line or essentially in a straight line.

The second flow path expediently runs parallel or essentially parallel to the separating element. This also simplifies the structure of the device.

The second flow path is preferably delimited by a fluid-impermeable delimiting surface opposite the separating element. This makes it possible, in particular, that a fluid can flow through the second flow path only in through the inlet and out again through the outlet.

A simple construction of the device can in particular be achieved in that the delimiting surface runs parallel or essentially parallel to the separating element.

According to a further preferred embodiment of the invention it can be provided that the delimiting surface is designed to be adjustable for adjusting an angle enclosed between the separating element and the delimiting surface. In this way, a fluid flow through the second flow path can in particular be influenced.

In order to simulate flows in turbine stages with identical turbine blades, it is advantageous if all profile bodies are of identical design. Of course, it is alternatively also possible to design the profile bodies differently. For example, in the case of turbines, turbine blades can be provided in two different shapes, which are arranged alternately and are flowed around.

In order to be able to simulate an outflow of an infinite cascade as well as possible with the device, it is advantageous if a number of Profile body of the profile body cascade is in a range from 4 to 15. In particular, it can be in a range from 6 to 10.

Furthermore, it is favorable if the profile body ends of the profile bodies define a common profile body end surface, in particular a plane, and if the profile body end surface and the separating element enclose an opening angle. Such an arrangement enables in particular an expansion of the fluid flow after flowing through the profile body cascade into the flow path outlet section towards the fluid outlet.

The opening angle is preferably in a range from approximately 5 ° to approximately 30 °. In particular, it can be in a range from approximately 10 ° to approximately 20 °. Providing opening angles in the specified ranges makes it possible, in particular, to implement a boundary condition with the separating element in connection with the second flow path, which corresponds or substantially corresponds to or at least comes very close to an outflow of the fluid flow through the profile body cascade into a free, unlimited space.

It is advantageous if the separating element is designed to be adjustable for setting the opening angle. This makes it possible to conduct examinations with different opening angles.

Furthermore, it is advantageous if a first side surface of the separating element, which faces the profile body cascade, is designed to be planar or essentially planar. Such a separating element can be formed in a simple manner, for example from a plate.

Furthermore, it can be advantageous, in particular also in the case of a device of the type described at the beginning, if the separating element has a plurality of perforations. The separating element is thus embodied in particular to be fluid-permeable, so that compression surges in the flow path outlet section are not reflected on the separating element. Compression shocks produce a local excess of fluid, which can be diverted through the openings in the separating element into the second flow path in order to avoid the undesired reflections. In particular, the separating element can have a surface structure, for example a three-dimensional one, on a second side face, which faces away from the profile body cascade. For example, the separating element can have a plurality of depressions on the second side surface facing away from the profile body cascade, in particular in the area of the perforations. Such a configuration makes it easier to divert the local excess of fluid generated by compression surges through the perforations. In particular, it is advantageous if the separating element is designed with the plurality of openings in such a way that all edges, in particular the edges delimited by the openings, are sharp-edged and not rounded. In this way, a clean separation can be achieved and, in particular, reflections in the area of edges that limit the openings can be prevented.

The plurality of perforations is preferably designed in the shape of a nozzle. The openings are preferably designed to taper in cross section in the direction of the profile body cascade. Conversely, this makes it possible to pass compression shocks emanating from the profile body cascade in the direction of the separating element in a simple manner through the openings without the compression shocks being reflected on the separating element.

The separating element can be designed in a three-dimensional structure in a simple manner if the plurality of perforations widens conically in the direction of the second flow path. In particular, funnel-shaped depressions are formed in the direction of the second flow path, which give the separating element a three-dimensional structure.

It is favorable if a cone angle of the plurality of perforations is in a range from approximately 90 ° to approximately 150 °. In particular, the cone angle can be in a range from approximately 110 ° to approximately 130 °. Such cone angles make it possible in particular, on the one hand, to form a sufficiently stable separating element and, on the other hand, to effectively prevent the reflection of compression shocks on the separating element. For example, the cone angle can be 118 °, which can be easily formed with conventional twist drills or countersink drills with an end angle corresponding to this cone angle

It is favorable if the plurality of perforations is arranged in a regular or an irregular pattern. In particular, the formation of a regular pattern simplifies the production of the separating element.

It is advantageous if the plurality of openings is arranged in a hexagonal pattern, in which pattern each opening is surrounded by six openings. Due to a finite width or height of the separating element, which is predetermined, for example, by a distance between the two wall surfaces facing one another, it may well be that not every opening is surrounded by six openings. This is particularly true Openings on the edge of the separating element. Nevertheless, the pattern is hexagonal if the perforations are arranged regularly in the manner described.

The separating element and thus the device as a whole can be formed in a simple manner if the plurality of perforations is formed identically.

It is favorable if the plurality of openings is each designed to be rotationally symmetrical with respect to a longitudinal axis of the opening defined by the respective opening. The openings can be formed in a simple manner, for example by drilling or milling.

For the production of the separating element in particular, it is advantageous if the longitudinal axis of the opening extends transversely to the separating element. In particular, it can run perpendicular to the separating element, so that the openings can be formed simply by drilling.

Furthermore, it can be advantageous if the longitudinal axis of the opening is inclined in the direction of the outlet and includes an opening angle with the separating element. Such a configuration can in particular contribute to further reducing reflections from compression shocks on the separating element.

The plurality of perforations is preferably designed in the form of bores. Separating elements with openings shaped in this way are easy to manufacture.

It is favorable if a minimum diameter of the plurality of openings is in a range from approximately 0.5 mm to approximately 2.1 mm; in particular, a minimum diameter of the openings can be in a range from approximately 1.0 mm to approximately 1.6 mm lie. Dimensioning the openings in this way makes it possible, in particular, to achieve the desired optimal boundary conditions with the separating element.

A ratio of a total opening area defined by the plurality of openings based on a total area of the separating element is preferably in a range from approximately 0.1 to approximately 0.5. The greater the ratio, the easier it is to prevent compression shocks from being reflected on the separating element.

It is also advantageous if the separating element has a thickness in a range from approximately 0.3 mm to approximately 1 mm. The thinner the separating element, the sooner it can be achieved that compression shocks striking the separating element are sufficiently attenuated in order to prevent undesired reflection of the compression shocks as effectively as possible.

A ratio of the thickness to the diameter of the plurality of perforations is advantageously in a range from approximately 0.1 to approximately 1. In particular, the ratio can be in a range from approximately 0.2 to approximately 0.6. Such a ratio has a particularly favorable effect on the stability of the separating element and its desired effect, namely to achieve a defined boundary condition for the outflow of the fluid flow through the profile cascade.

In order, in particular, to make it easier to carry out examinations, it is advantageous if the inlet and / or the outlet and / or the fluid outlet open into the surroundings of the device. This can in particular be achieved safely if air or an inert gas such as nitrogen, helium, water vapor or carbon dioxide is used as the fluid in order to carry out flow tests. No additional precautions then have to be taken to collect the fluids after they have flowed through the device.

The object set at the beginning is achieved according to the invention in a system of the type described at the outset in that the system comprises one of the devices described above and a fluid source for generating a fluid flow, the fluid source and the fluid inlet being fluidically connected to one another.

With such a system, studies of the flow around turbine blades with supersonic outflow can be carried out in a simple manner.

The configuration of the system can in particular be simplified by the fact that the fluid source comprises a liquid gas store and / or a pressurized gas store. Such fluid sources make it possible in a simple manner to provide a fluid flow at a desired speed and a desired pressure before flowing through the profile body cascade.

The object set at the beginning is also achieved according to the invention in a method of the type described at the beginning in that a fluid flow component of the first fluid flow is guided from the flow path inlet section through a secondary flow path into a second flow path with an inlet and an outlet in order to generate a free jet in the second flow path towards the outlet, that the second flow path is separated from the flow path outlet section by the separating element, that the secondary flow path connects the flow path inlet section and the second flow path to one another in a fluid-effective manner, that the fluid flow component flows around the first profile body, which is farthest from the fluid outlet, and that the fluid flow component defines a secondary flow path outlet direction into the second flow path that is parallel or essentially parallel to the separating element runs.

As already explained above, a negative pressure corresponding to the flow velocity of the fluid flow can be generated in the second flow path by the fluid flow portion which flows through the secondary flow path in order to facilitate passage of fluid through the separating element if it is perforated. In particular, no pressure control is required to control a pressure in the second flow path. By appropriately guiding the secondary flow path, it is possible, purely geometrically, to achieve an optimal adaptation of the pressure conditions in the second flow path and in the flow path outlet section. In particular, the pressures in these two areas are approximately the same.

Schlieren images of the fluid flow flowing through the profile body cascade are preferably recorded. In this way, a fluid flow can be made visible in a simple manner.

The method can be carried out in a simple manner if the second flow path is connected to an environment in a fluidically effective manner. In particular, the inlet and outlet of the second flow path can be fluidly connected to an environment. A fluid flow through the second flow path is induced in particular by the fluid flow portion of the first fluid flow which flows through the secondary flow path and flows into the second flow path.

Furthermore, the use of one of the devices described above and one of the systems described above for performing one of the methods described above is proposed. In this way, flow conditions in turbine stages can be simulated and observed in a simple way.

1. 1. Vorrichtung (12) zur Untersuchung der Umströmung von Turbinenschaufeln mit Überschall-Abströmung, welche Vorrichtung (12) einen ersten Strömungspfad (66) zwischen einem Fluideinlass (18) und einem Fluidauslass (20) aufweist, wobei im ersten Strömungspfad (66) zwischen dem Fluideinlass (18) und dem Fluidauslass (20) eine Profilkörperkaskade (22) mit einer Mehrzahl von Profilkörpern (24; 24a-24f) angeordnet ist, wobei benachbarte Profilkörper (24; 24a-24f) voneinander beabstandet sind und einen Profilströmungspfadabschnitt (72) zwischen sich definieren, wobei der erste Strömungspfad (66) zwischen dem Fluideinlass (18) und der Profilkörperkaskade (22) einen Strömungspfadeinlassabschnitt (80) und zwischen der Profilkörperkaskade (22) und dem Fluidauslass (20) einen Strömungspfadauslassabschnitt (82) definiert und wobei der Strömungspfadauslassabschnitt (82) von einem fluiddurchlässigen Trennelement (96) begrenzt ist, dadurch gekennzeichnet, dass die Vorrichtung (12) einen zweiten Strömungspfad (68) mit einem Einlass (26) und einem Auslass (28) aufweist, dass der zweite Strömungspfad (68) vom Strömungspfadauslassabschnitt (82) durch das Trennelement (96) getrennt ist, dass die Vorrichtung (12) einen Nebenströmungspfad (106) aufweist, dass der Nebenströmungspfad (106) den Strömungspfadeinlassabschnitt (80) und den zweiten Strömungspfad (68) fluidwirksam miteinander verbindet, dass der Nebenströmungspfad (106) vom ersten Profilkörper (24a), der vom Fluidauslass (20) am weitesten entfernt ist, begrenzt ist und dass der Nebenströmungspfad (106) eine Nebenströmungspfadauslassrichtung (108) in den zweiten Strömungspfad (68) hinein definiert, die parallel oder im Wesentlichen parallel zum Trennelement (96) verläuft.
2. 2. Vorrichtung nach Satz 1, dadurch gekennzeichnet, dass eine vom Fluideinlass (18) abgewandte Seitenfläche (74) des ersten Profilkörpers (24a) den zweiten Strömungspfad (68) begrenzt.
3. 3. Vorrichtung nach einem der voranstehenden Sätze, dadurch gekennzeichnet, dass der erste Strömungspfad (66) und der zweite Strömungspfad (68) zwischen aufeinander zu weisenden, insbesondere parallel zueinander verlaufenden, Wandflächen (62, 64) ausgebildet sind.
4. 4. Vorrichtung nach Satz 3, dadurch gekennzeichnet, dass das Trennelement quer, insbesondere senkrecht, zu den Wandflächen (62, 64) ausgerichtet ist.
5. 5. Vorrichtung nach Satz 3 oder 4, dadurch gekennzeichnet, dass die Wandflächen von Seitenflächen (58, 60) im sichtbaren Spektralbereich durchsichtiger Platten (54, 56), insbesondere Kunststoffplatten oder Glasplatten, definiert sind.
6. 6. Vorrichtung nach einem der voranstehenden Sätze, dadurch gekennzeichnet, dass das Trennelement (96) an ein in Richtung auf den Fluidauslass (20) hin weisendes Profilkörperende (94) des ersten Profilkörpers (24a) anschließend angeordnet ist.
7. 7. Vorrichtung nach einem der voranstehenden Sätze, dadurch gekennzeichnet, dass eine Einlassrichtung (70) des Fluideinlasses (18) und eine Auslassrichtung (76) des Fluidauslasses (20) einen Umlenkwinkel (78) einschließen.
8. 8. Vorrichtung nach Satz 7, dadurch gekennzeichnet, dass die Auslassrichtung durch oder im Wesentlichen durch eine Ausrichtung (76) von dem Fluideinlass (18) abgewandten Profilkörperseitenflächen (74) der Profilkörper (24a-24f) relativ zur Einlassrichtung (70) definiert ist.
9. 9. Vorrichtung nach Satz 8, dadurch gekennzeichnet, dass die von dem Fluideinlass (18) abgewandten Profilkörperseitenflächen (74) eben oder im Wesentlichen eben sind.
10. 10. Vorrichtung nach einem der Sätze 7 bis 9, dadurch gekennzeichnet, dass das Trennelement (96) parallel oder im Wesentlichen parallel zur Auslassrichtung (76) verlaufend angeordnet ist.
11. 11. Vorrichtung nach einem der voranstehenden Sätze, dadurch gekennzeichnet, dass der zweite Strömungspfad (68) eine Strömungsrichtung definiert, welche geradlinig oder im Wesentlichen geradlinig verläuft.
12. 12. Vorrichtung nach einem der voranstehenden Sätze, dadurch gekennzeichnet, dass der zweite Strömungspfad (68) parallel oder im Wesentlichen parallel zum Trennelement (96) verläuft.
13. 13. Vorrichtung nach einem der voranstehenden Sätze, dadurch gekennzeichnet, dass der zweite Strömungspfad (68) von einer dem Trennelement (96) gegenüberliegenden fluidundurchlässigen Begrenzungsfläche (102) begrenzt ist.
14. 14. Vorrichtung nach Satz 13, dadurch gekennzeichnet, dass die Begrenzungsfläche (102) parallel oder im Wesentlichen parallel zum Trennelement (96) verläuft.
15. 15. Vorrichtung nach Satz 13 oder 14, dadurch gekennzeichnet, dass die Begrenzungsfläche (102) verstellbar ausgebildet ist zum Verstellen eines zwischen dem Trennelement (96) und der Begrenzungsfläche (102) eingeschlossenen Winkels (112).
16. 16. Vorrichtung nach einem der voranstehenden Sätze, dadurch gekennzeichnet, dass alle Profilkörper (24a-24f) identisch ausgebildet sind.
17. 17. Vorrichtung nach einem der voranstehenden Sätze, dadurch gekennzeichnet, dass eine Anzahl der Profilkörper (24) der Profilkörperkaskade (22) in einem Bereich von 4 bis 15 liegt, insbesondere in einem Bereich von 6 bis 10.
18. 18. Vorrichtung nach einem der voranstehenden Sätze, dadurch gekennzeichnet, dass Profilkörperenden (94) der Profilkörper (24a-24f) eine gemeinsame Profilkörperendenfläche (114), insbesondere eine Ebene (116), definieren und dass die Profilkörperendenfläche (114) und das Trennelement (96) einen Öffnungswinkel (118) einschließen.
19. 19. Vorrichtung nach Satz 18, dadurch gekennzeichnet, dass der Öffnungswinkel (118) in einem Bereich von etwa 5° bis etwa 30° liegt, insbesondere in einem Bereich von etwa 10° bis etwa 20°.
20. 20. Vorrichtung nach Satz 18 oder 19, dadurch gekennzeichnet, dass das Trennelement (96) verstellbar ausgebildet ist zum Einstellen des Öffnungswinkels (118).
21. 21. Vorrichtung nach einem der voranstehenden Sätze, dadurch gekennzeichnet, dass eine erste Seitenfläche (98) des Trennelements (96), die der Profilkörperkaskade (22) zugewandt ist, eben oder im Wesentlichen eben ausgebildet ist.
22. 22. Vorrichtung nach einem der voranstehenden Sätze, insbesondere nach dem Oberbegriff des Satzes 1, dadurch gekennzeichnet, dass das Trennelement (96) eine Mehrzahl von Durchbrechungen (120) aufweist.
23. 23. Vorrichtung nach Satz 22, dadurch gekennzeichnet, dass die Mehrzahl von Durchbrechungen (120) düsenförmig ausgebildet ist.
24. 24. Vorrichtung nach Satz 22 oder 23, dadurch gekennzeichnet, dass sich die Mehrzahl von Durchbrechungen (120) in Richtung auf den zweiten Strömungspfad (68) hin konisch erweitert.
25. 25. Vorrichtung nach Satz 24, dadurch gekennzeichnet, dass ein Konuswinkel (122) der Mehrzahl von Durchbrechungen (120) in einem Bereich von etwa 90° bis etwa 150° liegt, insbesondere in einem Bereich von etwa 110° bis etwa 130°.
26. 26. Vorrichtung nach einem der Sätze 22 bis 25, dadurch gekennzeichnet, dass die Mehrzahl von Durchbrechungen (120) in einem regelmäßigen oder einem unregelmäßigen Muster angeordnet ist.
27. 27. Vorrichtung nach Satz 26, dadurch gekennzeichnet, dass die Mehrzahl von Durchbrechungen (120) in einem hexagonalen Muster angeordnet ist, bei welchem Muster jede Durchbrechung (120) von sechs Durchbrechungen (120) umgeben ist.
28. 28. Vorrichtung nach einem der Sätze 22 bis 27, dadurch gekennzeichnet, dass die Mehrzahl von Durchbrechungen (120) identisch ausgebildet ist.
29. 29. Vorrichtung nach einem der Sätze 22 bis 28, dadurch gekennzeichnet, dass die Mehrzahl von Durchbrechungen (120) jeweils rotationssymmetrisch bezogen auf eine von der jeweiligen Durchbrechung (120) definierte Durchbrechungslängsachse (124) ausgebildet ist.
30. 30. Vorrichtung nach Satz 29, dadurch gekennzeichnet, dass die Durchbrechungslängsachse (124) quer, insbesondere senkrecht, zum Trennelement (96) verläuft.
31. 31. Vorrichtung nach Satz 29 oder 30, dadurch gekennzeichnet, dass die Durchbrechungslängsachse (124) in Richtung auf den Auslass (28) hin geneigt ist und mit dem Trennelement (96) einen Durchbrechungswinkel einschließt.
32. 32. Vorrichtung nach einem der Sätze 22 bis 31, dadurch gekennzeichnet, dass die Mehrzahl von Durchbrechungen (120) in Form von Bohrungen (128) ausgebildet ist.
33. 33. Vorrichtung nach einem der Sätze 22 bis 32, dadurch gekennzeichnet, dass ein minimaler Durchmesser (130) der Mehrzahl von Durchbrechungen (120) in einem Bereich von etwa 0,5 mm bis etwa 2,1 mm liegt, insbesondere in einem Bereich von etwa 1,0 mm bis etwa 1,6 mm.
34. 34. Vorrichtung nach einem der Sätze 22 bis 33, dadurch gekennzeichnet, dass ein Verhältnis einer von der Mehrzahl von Durchbrechungen (120) definierten Gesamtdurchbrechungsfläche bezogen auf eine Trennelementgesamtfläche in einem Bereich von etwa 0,1 bis etwa 0,5 liegt.
35. 35. Vorrichtung nach einem der voranstehenden Sätze, dadurch gekennzeichnet, dass das Trennelement (96) eine Dicke (132) in einem Bereich von etwa 0,3 mm bis etwa 1 mm aufweist.
36. 36. Vorrichtung nach Satz 35, dadurch gekennzeichnet, dass ein Verhältnis der Dicke (132) zum minimalen Durchmesser (130) der Mehrzahl von Durchbrechungen (120) in einem Bereich von etwa 0,1 bis etwa 1 liegt, insbesondere in einem Bereich von etwa 0,2 bis etwa 0,6.
37. 37. Vorrichtung nach einem der voranstehenden Sätze, dadurch gekennzeichnet, dass der Einlass (26) und/oder der Auslass (28) und/oder der Fluidauslass (20) in eine Umgebung (30) der Vorrichtung (12) münden.
38. 38. System (10) zur Untersuchung der Umströmung von Turbinenschaufeln mit Überschall-Abströmung, welches System (10) eine Vorrichtung (12) nach einem der voranstehenden Sätze und eine Fluidquelle (14) umfasst zum Erzeugen einer Fluidströmung, wobei die Fluidquelle (14) und der Fluideinlass (18) fluidwirksam miteinander verbunden sind.
39. 39. System nach Satz 38, dadurch gekennzeichnet, dass die Fluidquelle einen Flüssiggasspeicher (34) und/oder einen Druckgasspeicher (42) umfasst.
40. 40. Verfahren zur Untersuchung der Umströmung von Turbinenschaufeln mit Überschall-Abströmung, bei welchem Verfahren eine erste Fluidströmung (134) durch einen ersten Strömungspfad (66) zwischen einem Fluideinlass (18) und einem Fluidauslass (20) erzeugt wird, wobei im ersten Strömungspfad (66) zwischen dem Fluideinlass (18) und dem Fluidauslass (20) eine Profilkörperkaskade (22) mit einer Mehrzahl von Profilkörpern (24; 24a-24f) angeordnet wird, wobei benachbarte Profilkörper (24; 24a-24f) voneinander beabstandet angeordnet werden und einen Profilströmungspfadabschnitt (72) zwischen sich definieren, wobei der erste Strömungspfad (66) zwischen dem Fluideinlass (18) und der Profilkörperkaskade (22) einen Strömungspfadeinlassabschnitt (80) und zwischen der Profilkörperkaskade (22) und dem Fluidauslass (20) einen Strömungspfadauslassabschnitt (82) definiert, wobei der Strömungspfadauslassabschnitt (82) von einem fluiddurchlässigen Trennelement (96) begrenzt wird, dadurch gekennzeichnet, dass ein Fluidströmungsanteil (136) der ersten Fluidströmung (134) vom Strömungspfadeinlassabschnitt (80) durch einen Nebenströmungspfad (106) in einen zweiten Strömungspfad (68) mit einem Einlass (26) und einem Auslass (28) hinein geleitet wird zum Erzeugen eines Freistrahls im zweiten Strömungspfad (68) in Richtung auf den Auslass (28) hin, dass der zweite Strömungspfad (68) vom Strömungspfadauslassabschnitt (82) durch das Trennelement (96) getrennt wird, dass der Nebenströmungspfad (106) den Strömungspfadeinlassabschnitt (80) und den zweiten Strömungspfad (68) fluidwirksam miteinander verbindet, dass der Fluidströmungsanteil (136) den ersten Profilkörper (24a), der vom Fluidauslass (20) am weitesten entfernt ist, umströmt und dass der Fluidströmungsanteil (136) eine Nebenströmungspfadauslassrichtung (108) in den zweiten Strömungspfad (68) hinein definiert, die parallel oder im Wesentlichen parallel zum Trennelement (96) verläuft.
41. 41. Verfahren nach Satz 40, dadurch gekennzeichnet, dass Schlierenbilder der die Profilkörperkaskade (22) durchströmenden Fluidströmung aufgenommen werden.
42. 42. Verfahren nach Satz 40 oder 41, dadurch gekennzeichnet, dass der zweite Strömungspfad (68) mit einer Umgebung (30) fluidwirksam verbunden wird.
43. 43. Verwendung einer Vorrichtung (12) nach einem der Sätze 1 bis 37 oder eines Systems (10) nach Satz 38 oder 39 zur Durchführung eines Verfahrens nach einem der Sätze 40 bis 42.

The above description therefore includes in particular the embodiments of devices, systems and methods for examining the flow around turbine blades with supersonic outflow defined in the form of consecutively numbered sentences:

1. 1. Device ( 12 ) to investigate the flow around turbine blades with supersonic flow, which device ( 12 ) a first flow path ( 66 ) between a fluid inlet ( 18th ) and a fluid outlet ( 20th ), wherein in the first flow path ( 66 ) between the fluid inlet ( 18th ) and the fluid outlet ( 20th ) a profile body cascade ( 22nd ) with a plurality of profile bodies ( 24 ; 24a-24f ) is arranged, with adjacent profile bodies ( 24 ; 24a-24f ) are spaced apart and have a profile flow path section ( 72 ) define between them, the first flow path ( 66 ) between the fluid inlet ( 18th ) and the profile body cascade ( 22nd ) a flow path inlet section ( 80 ) and between the profile body cascade ( 22nd ) and the fluid outlet ( 20th ) a flow path outlet section ( 82 ) and wherein the flow path outlet section ( 82 ) by a fluid-permeable separating element ( 96 ) is limited, characterized in that the device ( 12 ) a second flow path ( 68 ) with an inlet ( 26th ) and an outlet ( 28 ) has that the second flow path ( 68 ) from the flow path outlet section ( 82 ) through the separator ( 96 ) is separated, that the device ( 12 ) a bypass path ( 106 ) has that the secondary flow path ( 106 ) the flow path inlet section ( 80 ) and the second flow path ( 68 ) fluidly connects with each other that the secondary flow path ( 106 ) from the first profile body ( 24a ) coming from the fluid outlet ( 20th ) is furthest away, is limited and that the bypass flow path ( 106 ) a bypass path outlet direction ( 108 ) into the second flow path ( 68 ) which are parallel or essentially parallel to the separating element ( 96 ) runs.
2. 2. Device according to sentence 1, characterized in that one of the fluid inlet ( 18th ) remote side surface ( 74 ) of the first profile body ( 24a ) the second flow path ( 68 ) limited.
3. 3. Device according to one of the preceding sentences, characterized in that the first flow path ( 66 ) and the second flow path ( 68 ) between facing, in particular parallel, wall surfaces ( 62 , 64 ) are trained.
4. 4. Device according to sentence 3, characterized in that the separating element transversely, in particular perpendicular, to the wall surfaces ( 62 , 64 ) is aligned.
5. 5. Device according to sentence 3 or 4, characterized in that the wall surfaces of side surfaces ( 58 , 60 ) in the visible spectral range of transparent plates ( 54 , 56 ), in particular plastic plates or glass plates, are defined.
6. 6. Device according to one of the preceding sentences, characterized in that the Separator ( 96 ) to one in the direction of the fluid outlet ( 20th ) pointing profile body end ( 94 ) of the first profile body ( 24a ) is then arranged.
7. 7. Device according to one of the preceding sentences, characterized in that an inlet direction ( 70 ) of the fluid inlet ( 18th ) and an outlet direction ( 76 ) of the fluid outlet ( 20th ) a deflection angle ( 78 ) lock in.
8. 8. Device according to sentence 7, characterized in that the outlet direction by or essentially by an alignment ( 76 ) from the fluid inlet ( 18th ) facing profile body side surfaces ( 74 ) the profile body ( 24a-24f ) relative to the inlet direction ( 70 ) is defined.
9. 9. Device according to sentence 8, characterized in that the fluid inlet ( 18th ) facing profile body side surfaces ( 74 ) are flat or essentially flat.
10. 10. Device according to one of sentences 7 to 9, characterized in that the separating element ( 96 ) parallel or essentially parallel to the outlet direction ( 76 ) is arranged to run.
11. 11. Device according to one of the preceding sentences, characterized in that the second flow path ( 68 ) defines a direction of flow which is straight or substantially straight.
12. 12. Device according to one of the preceding sentences, characterized in that the second flow path ( 68 ) parallel or essentially parallel to the separating element ( 96 ) runs.
13. 13. Device according to one of the preceding sentences, characterized in that the second flow path ( 68 ) from one of the separating elements ( 96 ) opposite fluid-impermeable boundary surface ( 102 ) is limited.
14. 14. Device according to sentence 13, characterized in that the boundary surface ( 102 ) parallel or essentially parallel to the separating element ( 96 ) runs.
15. 15. Device according to sentence 13 or 14, characterized in that the boundary surface ( 102 ) is designed to be adjustable for adjusting one between the separating element ( 96 ) and the boundary surface ( 102 ) included angle ( 112 ).
16. 16. Device according to one of the preceding sentences, characterized in that all profile bodies ( 24a-24f ) are designed identically.
17. 17. Device according to one of the preceding sentences, characterized in that a number of the profile bodies ( 24 ) the profile body cascade ( 22nd ) is in a range from 4 to 15, in particular in a range from 6 to 10.
18. 18. Device according to one of the preceding sentences, characterized in that the profile body ends ( 94 ) the profile body ( 24a-24f ) a common profile body end face ( 114 ), especially one level ( 116 ), and that the extrusion end face ( 114 ) and the separator ( 96 ) an opening angle ( 118 ) lock in.
19. 19. Device according to sentence 18th , characterized in that the opening angle ( 118 ) is in a range from about 5 ° to about 30 °, in particular in a range from about 10 ° to about 20 °.
20. 20. Device according to sentence 18th or 19, characterized in that the separating element ( 96 ) is adjustable for setting the opening angle ( 118 ).
21. 21. Device according to one of the preceding sentences, characterized in that a first side surface ( 98 ) of the separator ( 96 ), the profile body cascade ( 22nd ) is facing, is flat or substantially flat.
22. 22. Device according to one of the preceding sentences, in particular according to the preamble of sentence 1, characterized in that the separating element ( 96 ) a plurality of perforations ( 120 ) having.
23. 23. Device according to sentence 22nd , characterized in that the plurality of perforations ( 120 ) is nozzle-shaped.
24. 24. Device according to sentence 22nd or 23, characterized in that the plurality of perforations ( 120 ) in the direction of the second flow path ( 68 ) widened conically.
25. 25. Device according to sentence 24 , characterized in that a cone angle ( 122 ) the plurality of perforations ( 120 ) is in a range from about 90 ° to about 150 °, in particular in a range from about 110 ° to about 130 °.
26. 26. Device according to one of the sentences 22nd to 25, characterized in that the plurality of perforations ( 120 ) is arranged in a regular or an irregular pattern.
27. 27. Device according to sentence 26th , characterized in that the plurality of perforations ( 120 ) is arranged in a hexagonal pattern, in which pattern each perforation ( 120 ) of six breakthroughs ( 120 ) is surrounded.
28. 28. Device according to one of the sentences 22nd to 27, characterized in that the plurality of openings ( 120 ) is designed identically.
29. 29. Device according to one of the sentences 22nd to 28 , characterized in that the plurality of perforations ( 120 ) each rotationally symmetrical in relation to one of the respective opening ( 120 ) defined longitudinal axis of the opening ( 124 ) is trained.
30. 30. Device according to sentence 29, characterized in that the opening longitudinal axis ( 124 ) across, especially perpendicular, to the separating element ( 96 ) runs.
31. 31. Device according to sentence 29 or 30th , characterized in that the longitudinal axis of the opening ( 124 ) towards the outlet ( 28 ) is inclined and with the separator ( 96 ) includes an opening angle.
32. 32. Device according to one of the sentences 22nd to 31, characterized in that the plurality of openings ( 120 ) in the form of holes ( 128 ) is trained.
33. 33. Device according to one of the sentences 22nd to 32 , characterized in that a minimum diameter ( 130 ) the plurality of perforations ( 120 ) is in a range from about 0.5 mm to about 2.1 mm, in particular in a range from about 1.0 mm to about 1.6 mm.
34. 34. Device according to one of the sentences 22nd to 33, characterized in that a ratio of one of the plurality of perforations ( 120 ) defined total opening area based on a separating element total area in a range from about 0.1 to about 0.5.
35. 35. Device according to one of the preceding sentences, characterized in that the separating element ( 96 ) a thickness ( 132 ) in a range from about 0.3 mm to about 1 mm.
36. 36. Device according to sentence 35, characterized in that a ratio of the thickness ( 132 ) to the minimum diameter ( 130 ) the plurality of perforations ( 120 ) is in a range from about 0.1 to about 1, in particular in a range from about 0.2 to about 0.6.
37. 37. Device according to one of the preceding sentences, characterized in that the inlet ( 26th ) and / or the outlet ( 28 ) and / or the fluid outlet ( 20th ) in an environment ( 30th ) of the device ( 12 ) flow.
38. 38.System ( 10 ) to investigate the flow around turbine blades with supersonic flow, which system ( 10 ) a device ( 12 ) according to one of the preceding sentences and a fluid source ( 14th ) comprises for generating a fluid flow, wherein the fluid source ( 14th ) and the fluid inlet ( 18th ) are fluidly connected to one another.
39. 39. System by theorem 38 , characterized in that the fluid source is a liquid gas storage ( 34 ) and / or a pressurized gas storage ( 42 ) includes.
40. 40. Method for investigating the flow around turbine blades with supersonic outflow, in which method a first fluid flow ( 134 ) through a first flow path ( 66 ) between a fluid inlet ( 18th ) and a fluid outlet ( 20th ) is generated, where in the first flow path ( 66 ) between the fluid inlet ( 18th ) and the fluid outlet ( 20th ) a profile body cascade ( 22nd ) with a plurality of profile bodies ( 24 ; 24a-24f ) is arranged, with adjacent profile bodies ( 24 ; 24a-24f ) are arranged at a distance from each other and a profile flow path section ( 72 ) define between them, the first flow path ( 66 ) between the fluid inlet ( 18th ) and the profile body cascade ( 22nd ) a flow path inlet section ( 80 ) and between the profile body cascade ( 22nd ) and the fluid outlet ( 20th ) a flow path outlet section ( 82 ), the flow path outlet section ( 82 ) by a fluid-permeable separating element ( 96 ) is limited, characterized in that a fluid flow component ( 136 ) of the first fluid flow ( 134 ) from the flow path inlet section ( 80 ) through a bypass path ( 106 ) into a second flow path ( 68 ) with an inlet ( 26th ) and an outlet ( 28 ) is passed into it to generate a free jet in the second flow path ( 68 ) towards the outlet ( 28 ) indicates that the second flow path ( 68 ) from the flow path outlet section ( 82 ) through the separator ( 96 ) is separated so that the secondary flow path ( 106 ) the flow path inlet section ( 80 ) and the second flow path ( 68 ) effectively connects with each other that the fluid flow component ( 136 ) the first profile body ( 24a ) coming from the fluid outlet ( 20th ) is farthest away, flows around and that the fluid flow portion ( 136 ) a bypass path outlet direction ( 108 ) into the second flow path ( 68 ) which are parallel or essentially parallel to the separating element ( 96 ) runs.
41. 41. Procedure according to sentence 40 , characterized in that Schlieren images of the profile body cascade ( 22nd ) flowing fluid flow can be recorded.
42. 42. Procedure according to sentence 40 or 41, characterized in that the second flow path ( 68 ) with an environment ( 30th ) is fluidly connected.
43. 43. Use of a device ( 12 ) according to one of the sentences 1 to 37 or a system ( 10 ) according to sentence 38 or 39 to carry out a procedure according to one of the sentences 40 to 42 .

• 1: eine schematische Darstellung eines Ausführungsbeispiels eines Systems zur Untersuchung der Strömung von Turbinenschaufeln mit Überschall-Abströmung;
• 2: eine schematische Darstellung eines weiteren Ausführungsbeispiels eines Systems zur Untersuchung der Umströmung von Turbinenschaufeln mit Überschall-Abströmung;
• 3: eine schematische perspektivische Darstellung einer Vorrichtung zur Untersuchung der Umströmung von Turbinenschaufeln mit Überschall-Abströmung, die einen Teil des in 2 dargestellten Ausführungsbeispiels eines System bildet;
• 4: eine Draufsicht auf die Anordnung aus 3 in Richtung des Pfeils A;
• 5: eine Ansicht der Anordnung aus 4 in Richtung des Pfeils B;
• 5A: eine vergrößerte Ansicht des Teilbereichs C aus 5;
• 6: eine schematische Draufsicht eines Trennelements auf dessen von der Profilkörperkaskade weg weisenden Seitenfläche;
• 7: eine Schnittansicht längs Linie 7-7 in 6;
• 8: ein HintergrundschlierenBild eines Strömungsversuchs mit dem in Figur dargestellten Ausführungsbeispiel eines Systems;
• 9: ein weiteres Hintergrundschlierenbild eines Strömungsversuchs;
• 10: eine Darstellung des Ergebnisses einer CFD-(Computational Fluid Dynamics)-Rechnung eines Ausführungsbeispiels einer Vorrichtung ohne Trennelement;
• 11: eine Darstellung der Berechnung analog der Berechnung zu 10, jedoch mit fluidundurchlässigem Trennelement; und
• 12: eine Darstellung des Ergebnisses einer CFD-Rechnung analog 10, jedoch mit einem perforierten Trennelement mit einem Lochdurchmesser von 1,3 mm.

The following description of preferred embodiments of the invention is used in conjunction with the drawings for a more detailed explanation. Show it:

• 1 : a schematic representation of an embodiment of a system for examining the flow of turbine blades with supersonic outflow;
• 2 : a schematic representation of a further embodiment of a system for investigating the flow around turbine blades with supersonic outflow;
• 3 : a schematic perspective representation of a device for examining the flow around turbine blades with supersonic outflow, which is part of the in 2 illustrated embodiment of a system;
• 4th : a plan view of the arrangement 3 in the direction of arrow A;
• 5 : a view of the arrangement 4th in the direction of arrow B;
• 5A : an enlarged view of the portion C. 5 ;
• 6th : a schematic plan view of a separating element on its side surface facing away from the profile body cascade;
• 7th Figure 7 is a sectional view taken along line 7-7 in 6th ;
• 8th : a background streak image of a flow test with the embodiment of a system shown in FIG.
• 9 : Another background streak image of a flow test;
• 10 : a representation of the result of a CFD (Computational Fluid Dynamics) calculation of an exemplary embodiment of a device without a separating element;
• 11 : a representation of the calculation analogous to the calculation 10 but with a fluid-impermeable separating element; and
• 12 : a representation of the result of a CFD calculation analog 10 , but with a perforated separator with a hole diameter of 1.3 mm.

A first embodiment of a system 10 for the investigation of the flow around turbine blades with supersonic outflow is schematically in 1 shown.

The system 10 includes a device 12 for the investigation of the flow around turbine blades with supersonic flow and a fluid source 14th for creating a fluid flow. The fluid source 14th is via a connecting line 16 with a fluid inlet 18th the device 12 fluidly connected.

The device 12 includes a first, in 1 flow path, not shown, between the fluid inlet 18th and a fluid outlet 20th . The first flow path is between the fluid inlet 18th and the fluid outlet 20th a profile body cascade 22nd with a plurality of profile bodies 24 arranged.

The device 12 further comprises a second, in 1 flow path not shown in detail with an inlet 26th and an outlet 28 . The fluid outlet 20th and the outlet 28 are arranged side by side and allow fluid to flow out of the device 12 in an environment 30th of the system 10 .

2 shows a further embodiment of a total also with the reference number 10 designated system for investigating the flow around turbine blades with supersonic outflow. The schematic in the box 32 illustrated device 12 is in 2 Enlarged on the right and shown with a higher level of detail.

The fluid source 14th includes a tank 34 which is filled with liquid nitrogen. The Tank 34 has a volume of 20 m ³ . The liquid nitrogen is in the tank 34 under a pressure of 0.9 MPa.

The Tank 34 is via the connecting line 16 with the fluid inlet of the device 12 fluidly connected. In the connecting line 16 is a valve 36 arranged to allow the flow of liquid nitrogen through the connecting line 16 into the device 12 adjust into it.

The Tank 34 is via another connection line 38 in which a valve 40 is arranged with another tank 42 fluidly connected. The Tank 42 has a volume of 10 m ³ and is filled with gaseous nitrogen and a pressure of 20 MPa.

One pump 44 for conveying liquid nitrogen is via a connecting line 46 with a vaporizer 48 fluidly connected. The evaporator 48 is in turn via a connecting line 50 with the tank 42 fluidly connected.

With the fluid source 14th can of the device 12 liquid nitrogen can be supplied under a defined pressure and at a defined flow rate. With the valve 40 can be the pressure in the tank 34 by appropriately supplying pressurized gaseous nitrogen from the tank 42 to be controlled.

The structure of the device 12 will be used in connection with the 2 to 7th explained in more detail.

That into the device 12 Inflowing fluid comes out of the connecting line 16 first in an antechamber 52 . The antechamber 52 is laterally open and fluid-tight with the fluid inlet 18th the device 12 coupled.

The device 12 comprises two plates arranged parallel to one another 54 and 56 , which are formed from a transparent plastic. In the exemplary embodiment shown in the figures, the plastic is PMMA.

Side faces facing one another 58 and 60 of the plates 54 and 56 form wall surfaces 62 and 64 , between which a first flow path 66 and a second flow path 68 are trained.

The fluid inlet 18th is formed by an opening through which the fluid in the direction of an inlet direction 70 indicating arrow flows through and on the profile body cascade 22nd meets, which in the embodiment shown in the figures, seven profile bodies 24a-24f includes.

Adjacent profile bodies 24a-24f are spaced from one another and define profile flow path sections between them 72 .

The profile body 24a-24f show in a cross-sectional view as shown schematically in 4th is shown, a streamline profile on with a planar, from the fluid inlet 18th facing away profile body side surfaces 74 that are flat or substantially flat.

The profile body side surfaces 74 the profile body 24a-24f point parallel to an outlet direction indicated by an arrow 76 towards the fluid outlet 20th down.

The inlet direction 70 of the fluid inlet 18th and the outlet direction 76 of the fluid outlet 20th close a deflection angle 78 one, which in the described embodiment has a value of about 105 °.

The first flow path 66 defined between the fluid inlet 18th and the profile body cascade 22nd a flow path inlet section 80 and between the profile body cascade 22nd and the fluid outlet 20th a flow path outlet portion 82 . The flow path inlet section 82 is both through the wall surfaces 62 and 64 as well as by two wall surfaces facing each other 84 and 86 limited that is perpendicular to the wall surfaces 62 and 64 as well as parallel to each other and to the inlet direction 70 run away.

The wall surface 84 ends with her on the profile body cascade 22nd pointing end on a curved guide surface 88 whose shape is directed towards the fluid inlet 18th pointing profile body side surface 90 the profile body 24a-24f corresponds.

The profile body face 90 forms a pressure side of the profile body 24a-24f . The profile body face 74 forms a suction side of the profile body 24a-24f .

One from the fluid inlet 18th facing away end of the wall surface 86 closes on a guide surface 92 whose shape of the profile body side surface 74 corresponds.

The profile body cascade 22nd is linear and defines a total of seven profile flow path sections 72 that are located between the guide surface 88 and the guide surface 92 as well as the profile bodies 24a and 24f extend. The profile flow path sections 72 taper in their cross section in the direction of the fluid outlet 20th so that in the inlet direction 70 on the profile body cascade 22nd impinging fluid in the outlet direction 76 is deflected and accelerated, so that the profile body ends pointing in the direction of the fluid outlet 94 the profile body 24a-24f be flowed around by the fluid flow at supersonic speed.

The flow path outlet section 82 is the profile bodies 24b-24f opposite from a separating element 96 limited, which is fluid-permeable and is described in more detail below.

The separator 90 has a first side face 98 on that in the direction of the profile body 24b-24f points out. A second side face 100 of the separator 96 points from the profile body cascade 22nd away and limits the second flow path 66 .

Parallel to the separator 96 runs a fluid-impermeable boundary surface 102 moving away from the inlet 26th to the outlet 28 extends. Parallel to the boundary surface 102 extends from the inlet 26th a boundary surface 104 to the end of the profile body 94 the guide surface 88 .

The separator 96 separates the second flow path as described 68 from the flow path outlet section 82 .

The device 12 also has a bypass flow path 106 which through the profile flow path section 72 between the guide surface 88 and the profile body side surface 74 of the profile body 24a is formed. Thus the secondary flow path connects 106 the flow path inlet portion 70 and the second flow path 68 fluidly with each other.

The tributary path 106 is from the profile body 24a , the first profile body 24a forms that of the fluid outlet 20th furthest away is limited.

By the shape of the profile flow path section 72 , the bypass flow path section 106 forms, a secondary flow path outlet direction symbolized by an arrow 108 defined in the second flow path 68 is directed into it and which is parallel or substantially parallel to the separating element 96 runs.

The one from the fluid inlet 18th averted profile body side surface 74 of the first profile body 24a limits the second flow path as described 68 .

The separator 96 is at that in the direction of the fluid outlet 20th pointing profile body end 94 of the first profile body 24a subsequently arranged.

The second flow path 68 defines a flow direction symbolized by an arrow 110 that are parallel to the outlet direction 26th is directed. This enables it to pass through the flow path outlet section 82 and the second flow path 68 fluid flowing through the fluid outlet 20th and that of this only through the separating element 96 separate outlet 28 can flow out together. The separator 96 is thus parallel or essentially parallel to the outlet direction 76 arranged.

The second flow path described 68 gives the direction of flow 110 straight or essentially straight ahead. The flow path 68 thus also runs parallel or essentially parallel to the separating element 96 .

In an alternative embodiment, which is not shown in the figures, the boundary surface 102 adjustable designed for adjusting one between the separating element 96 and the boundary surface 102 included angle 112 . The angle 112 is 0 ° in the embodiment shown in the figures, because the separating element 96 and the boundary surface 102 run parallel to each other.

The profile body cascade 22nd In alternative exemplary embodiments, a different number of profile bodies can also be used 24 The number can be, for example, in a range from 4 to 15.

The profile body ends 94 the profile body 24a-24f define a common extrusion end surface 114 that touches this and in the embodiment shown in the figures, a plane 116 Are defined. This profile body end face 114 or the plane 116 on the one hand and the separating element 96 on the other hand define an opening angle between them 118 , which in the exemplary embodiment shown in the figures has a value of approximately 14 °, that is to say is in a range from approximately 5 ° to approximately 30 °.

In an embodiment not shown in the figures, the separating element 96 adjustable designed to vary or adjust the opening angle 118 .

The first face 98 of the separator 96 is flat or essentially flat.

The second side face 100 of the separator 96 is structured three-dimensionally, which will be explained in detail below.

6th shows schematically a plan view of the side surface 100 of the separator 96 .

The separator 96 has a plurality of perforations 120 on, which are nozzle-shaped. The breakthroughs 120 expand from the first side face 98 to the second side surface 100 towards, therefore in the direction of the second flow path 68 down, conical.

A cone angle 122 of the breakthroughs 120 is about 118 °, therefore lies in a range from about 90 ° to about 150 °.

As exemplified in 6th the majority of openings can be seen 120 arranged in a regular pattern. This pattern is a hexagonal pattern in which each perforation 120 of six more breakthroughs 120 is surrounded.

In the embodiment shown in the figures, the openings are 120 designed identically.

The breakthroughs 120 are each rotationally symmetrical with respect to one of the respective opening 120 defined longitudinal axis of the opening 124 educated. The longitudinal axis of the opening 124 runs transversely, perpendicular in the exemplary embodiments shown in the figures, to the separating element 96 or a center plane defined by this 126 .

In a further embodiment, the opening is longitudinal axis 124 towards the outlet 28 inclined towards and closes with the separator 96 an opening angle.

The majority of breakthroughs 120 is in the form of holes 128 educated.

A minimum diameter 130 of the breakthroughs 120 is 1.3 mm and is thus in a range from about 0.5 mm to about 2.1 mm.

The majority of breakthroughs 120 defines a total opening area. A ratio of the total opening area and a total area defined by the separating element, which is defined by one of the two side surfaces 98 respectively 100 is defined, is in the described embodiment in a range from about 0.1 to about 0.5.

The separator 96 has a thickness in the described exemplary embodiments 132 which is about 4 mm, therefore in a range from about 0.3 mm to about 1 mm.

A ratio of thickness 132 to the minimum diameter 130 of the breakthroughs 120 is in a range from approximately 0.1 to approximately 1 in the exemplary embodiments described. This ratio is preferably in a range from approximately 0.2 to approximately 0.6.

As already mentioned, the inlet ends 26th the outlet 28 and the fluid outlet 20th in an environment 30th the device 12 .

With the system 10 that the device 12 includes, in particular, a method for examining the flow around turbine blades with supersonic outflow can be carried out. In this process, a first flow of fluid 134 , symbolized by an arrow in 2 , through the first flow path 66 directed. The fluid flow 134 is through the fluid source 14th fed.

A fluid flow fraction 136 the first fluid flow 134 becomes from the flow path inlet section 80 through the bypass path 106 into the second flow path 68 guided in to generate a free jet in the second flow path 68 towards the outlet 28 down.

Due to the transparent design of the plates 54 and 56 it is possible to create Schlieren images of the profile body cascade 22nd Record flowing fluid flow.

To carry out flow tests, the in the antechamber 52 prevailing pressure increased up to a desired pressure ratio. Gaseous fluid now flows through the inlet 18th into the device 12 inside. Through the intended secondary flow path 106 a gas stream is also entrained from the environment, which the second flow path 68 from the inlet 26th to the outlet 28 flows through. The environment 30th can be open to the outside air in one embodiment. This is possible if an outlet pressure of 1 atm is desired and the test gas is air or a gas comparable to nitrogen.

The 8th and 9 show result images of a flow investigation with the device described 12 . In these pictures it is easy to see that it is in the immediate vicinity of the separating element 96 Although the fluid flow is influenced, this quickly subsides with increasing distance. As can be seen, however, the influence in the area of the 8th and 9 illustrated profile flow path sections 72 clearly distinguishable from the actual flow phenomenon to be observed.

Furthermore, in the 8th and 9 It is easy to see that a reflection of compression waves on the separating element 96 is almost completely eliminated.

The supersonic flow is on the first side surface 98 of the separator 96 at. If one looks at a single streamline, which is at an acute angle on the one through the perforations 120 meets defined structure, it can be deflected either tangentially or substantially tangentially to the first side surface, depending on the exact location at which it strikes 98 to run, or be diverted, to go through an opening 120 into the second flow path 68 to be relaxed into it. In the first case a shock wave is generated, in the second case an expansion fan. Because over a height of the separating element 96 which is defined by the distance between the two wall surfaces 62 and 64 , both processes occur simultaneously to a similar extent. Therefore, over a certain range of Mach numbers, there is almost complete extinction of these phenomena and thus to a very small influence on the distant flow. A prerequisite for this is, in particular, that a speed component of the fluid flow in the flow path outlet section 82 in the normal direction to the side surface 98 is relatively small, i.e. the flow is almost parallel to the separating element 96 or its first side surface 98 runs.

In the 10 to 12 results of CFD calculations for three different configurations are shown.

10 shows an ideal outflow of the profile body cascade 22nd . The profile body cascade is assumed here as an infinite cascade. A flow takes place here in an unlimited space, so that no reflections from shock waves can occur. So there is no separating element.

In contrast, shows 11 a calculated flow pattern of an infinite cascade with an impenetrable boundary surface 102 .

In 12 the same infinite cascade with outflow is shown, but with the impenetrable boundary surface 102 by a separator 96 is replaced. As can be clearly seen, the flow with the separating element of the ideal infinite cascade is much more similar than the arrangement with the flow conditions shown in 11 are shown. Impact reflections from the partition 96 are compared to the impenetrable boundary surface 102 greatly reduced. This makes it possible to use the separator 96 to create a periodic flow, as occurs in the ideal case. This is important for the flow investigations, since with a non-periodic flow it is difficult to determine on which of the profile flow path sections 72 Measurements should be made. In addition, the degree of expansion is significantly less influenced by the separating element than by an impermeable boundary surface 102 .

In the 10 to 12 each change in gray level corresponds to Mach 0.1. The first change in gray level when passing between the profile bodies corresponds to the passage of sound.

The described embodiments of devices 12 and systems 10 can be used particularly in the development of turbine profiles. Despite higher losses, strongly deflecting profiles with trans- or supersonic outlet flow are used in special applications such as in particular turbo pumps, organic Rankine cycle machines and supersonic aircraft engines. An observation of gas dynamic phenomena in the area of the flow outlet from the turbines gives indications of possible dynamic rotor loads already at an early point in the development of the turbines. In addition, the proposed devices allow 12 and systems 10 a validation of numerical models used in the development of turbine profiles for flow prediction in this particular case.

As described, there is an effort to carry out flow experiments with the proposed devices 12 and systems 10 compared to devices and systems known from the prior art, greatly reduced. In addition, significantly better results are possible.

List of reference symbols

10

system

12

contraption

14th

Fluid source

16

Connecting line

18th

Fluid inlet

20th

Fluid outlet

22nd

Profile body cascade

24, 24a, 24b, 24c, 24d, 24e, 24f

Profile body

26th

inlet

28

Outlet

30th

Surroundings

32

box

34

tank

36

Valve

38

Connecting line

40

Valve

42

tank

44

pump

46

Connecting line

48

Evaporator

50

Connecting line

52

Antechamber

54

plates

56

plates

58

Side face

60

Side face

62

Wall surface

64

Wall surface

66

first flow path

68

second flow path

70

Inlet direction

72

Profile flow path section

74

Profile body face

76

Outlet direction

78

Deflection angle

80

Flow path inlet section

82

Flow path outlet section

84

Wall surface

86

Wall surface

88

Guide surface

90

Profile body face

92

Guide surface

94

Profile body end

96

Separator

98

first side face

100

second side face

102

Boundary surface

104

Boundary surface

106

Secondary flow path

108

Bypass flow path outlet direction

110

Direction of flow

112

angle

114

Body end face

116

level

118

Opening angle

120

Breakthrough

122

Cone angle

124

Opening longitudinal axis

126

Middle plane

128

drilling

130

diameter

132

thickness

134

first fluid flow

136

Fluid flow fraction

Claims (20)

Device (12) for investigating the flow around turbine blades with supersonic outflow, which device (12) has a first flow path (66) between a fluid inlet (18) and a fluid outlet (20), wherein in the first flow path (66) between the fluid inlet (18) and the fluid outlet (20) a profile body cascade (22) with a plurality of profile bodies (24; 24a-24f) is arranged, wherein adjacent profile bodies (24; 24a-24f) are spaced from one another and a profile flow path section (72) between them define, wherein the first flow path (66) between the fluid inlet (18) and the profile body cascade (22) defines a flow path inlet section (80) and between the profile body cascade (22) and the fluid outlet (20) defines a flow path outlet section (82) and wherein the flow path outlet section ( 82) is delimited by a fluid-permeable separating element (96), characterized in that the device (12) has a second flow path (68) with an inlet (26) and an outlet (28), that the second flow path (68) is separated from the flow path outlet section (82) by the separating element (96), that the device (12) has a secondary flow path (106) comprises that the secondary flow path (106) fluidly connects the flow path inlet section (80) and the second flow path (68) so that the secondary flow path (106) is delimited by the first profile body (24a), which is furthest away from the fluid outlet (20) and that the secondary flow path (106) defines a secondary flow path outlet direction (108) into the second flow path (68) which runs parallel or substantially parallel to the separating element (96). Device according to Claim 1 , characterized in that a side surface (74) of the first profile body (24a) facing away from the fluid inlet (18) delimits the second flow path (68). Device according to one of the preceding claims, characterized in that the first flow path (66) and the second flow path (68) are formed between wall surfaces (62, 64) facing one another, in particular running parallel to one another. Device according to Claim 3 , characterized in that a) the separating element is aligned transversely, in particular perpendicular, to the wall surfaces (62, 64) and / or b) the wall surfaces of side surfaces (58, 60) are defined in the visible spectral range of transparent plates (54, 56), in particular plastic plates or glass plates are. Device according to one of the preceding claims, characterized in that the separating element (96) is arranged next to a profile body end (94) of the first profile body (24a) pointing in the direction of the fluid outlet (20). Device according to one of the preceding claims, characterized in that an inlet direction (70) of the fluid inlet (18) and an outlet direction (76) of the fluid outlet (20) enclose a deflection angle (78). Device according to Claim 6 , characterized in that a) the outlet direction is defined by or essentially by an alignment (76) facing away from the fluid inlet (18) profile body side surfaces (74) of the profile bodies (24a-24f) relative to the inlet direction (70), in particular that of the profile body side surfaces (74) facing away from the fluid inlet (18) are flat or essentially flat, and / or b) the separating element (96) is arranged to run parallel or essentially parallel to the outlet direction (76). Device according to one of the preceding claims, characterized in that the second flow path (68) a) defines a direction of flow which is straight or essentially straight, and / or b) runs parallel or essentially parallel to the separating element (96) and / or c) is delimited by a fluid-impermeable boundary surface (102) opposite the separating element (96), wherein in particular the boundary surface (102) runs parallel or essentially parallel to the separating element (96) and / or is designed to be adjustable for adjusting one between the separating element (96) ) and the boundary surface (102) included angle (112). Device according to one of the preceding claims, characterized in that a) all profile bodies (24a-24f) are identical and / or b) a number of profile bodies (24) of the profile body cascade (22) is in a range from 4 to 15, in particular in a range of 6 to 10, and / or c) profile body ends (94) of the profile bodies (24a-24f) define a common profile body end surface (114), in particular a plane (116), and that the profile body end surface (114) and the separating element ( 96) enclose an opening angle (118), in particular the opening angle (118) being in a range from about 5 ° to about 30 °, in particular in a range from about 10 ° to about 20 °, and / or d) a first side surface (98) of the separating element (96), which faces the profile body cascade (22), is flat or essentially flat. Device according to one of the preceding claims, in particular according to the preamble of Claim 1 , characterized in that the separating element (96) has a plurality of openings (120). Device according to Claim 10 , characterized in that a) the plurality of openings (120) is nozzle-shaped and / or b) the plurality of openings (120) widens conically in the direction of the second flow path (68), with a cone angle (122) in particular the plurality of perforations (120) is in a range from about 90 ° to about 150 °, in particular in a range from about 110 ° to about 130 °, and / or c) the plurality of perforations (120) in a regular or one irregular pattern is arranged, wherein in particular the plurality of openings (120) is arranged in a hexagonal pattern, in which pattern each opening (120) is surrounded by six openings (120), and / or d) the plurality of openings (120) is formed identically. Device according to Claim 10 or 11 , characterized in that the plurality of openings (120) is each designed to be rotationally symmetrical with respect to an opening longitudinal axis (124) defined by the respective opening (120). Device according to Claim 12 , characterized in that the opening longitudinal axis (124) a) runs transversely, in particular perpendicular, to the separating element (96) and / or b) is inclined towards the outlet (28) and forms an opening angle with the separating element (96). Device according to one of the Claims 10 to 13th , characterized in that a) the plurality of openings (120) is designed in the form of bores (128) and / or b) a minimum diameter (130) of the plurality of openings (120) in a range of approximately 0.5 mm up to about 2.1 mm, especially in a range from about 1.0 mm to about 1.6 mm, and / or c) a ratio of a total opening area defined by the plurality of openings (120) to a separating element total area in a range from about 0.1 to about 0.5 lies. Device according to one of the preceding claims, characterized in that the separating element (96) has a thickness (132) in a range from approximately 0.3 mm to approximately 1 mm, in particular a ratio of the thickness (132) to the minimum diameter (130 ) the plurality of perforations (120) lies in a range from approximately 0.1 to approximately 1, in particular in a range from approximately 0.2 to approximately 0.6. Device according to one of the preceding claims, characterized in that the inlet (26) and / or the outlet (28) and / or the fluid outlet (20) open into an environment (30) of the device (12). System (10) for investigating the flow around turbine blades with supersonic outflow, which system (10) comprises a device (12) according to one of the preceding claims and a fluid source (14) for generating a fluid flow, wherein the fluid source (14) and the Fluid inlet (18) are connected to one another in a fluid-effective manner, the fluid source in particular comprising a liquid gas reservoir (34) and / or a pressurized gas reservoir (42). Method for investigating the flow around turbine blades with supersonic outflow, in which method a first fluid flow (134) is generated through a first flow path (66) between a fluid inlet (18) and a fluid outlet (20), wherein in the first flow path (66) a profile body cascade (22) with a plurality of profile bodies (24; 24a-24f) is arranged between the fluid inlet (18) and the fluid outlet (20), adjacent profile bodies (24; 24a-24f) being arranged at a distance from one another and a profile flow path section ( 72) define between them, the first flow path (66) defining a flow path inlet section (80) between the fluid inlet (18) and the profile body cascade (22) and a flow path outlet section (82) between the profile body cascade (22) and the fluid outlet (20), wherein the flow path outlet section (82) is delimited by a fluid-permeable separating element (96), characterized in that a fluid flow portion (136) of the first fluid flow (134) is passed from the flow path inlet section (80) through a secondary flow path (106) into a second flow path (68) with an inlet (26) and an outlet (28) to generate a free jet in the second Flow path (68) in the direction of the outlet (28) that the second flow path (68) is separated from the flow path outlet section (82) by the separating element (96), that the secondary flow path (106) the flow path inlet section (80) and the second flow path (68) fluidly connects with each other that the fluid flow component (136) flows around the first profile body (24a), which is furthest away from the fluid outlet (20), and that the fluid flow component (136) flows in a secondary flow path outlet direction (108) into the second flow path (68) ) defined into it, which runs parallel or substantially parallel to the separating element (96). Procedure according to Claim 18 , characterized in that a) streak images of the fluid flow flowing through the profile body cascade (22) are recorded and / or b) the second flow path (68) is connected to an environment (30) in a fluid-effective manner. Use of a device (12) according to one of the Claims 1 to 16 or a system (10) Claim 17 to carry out a procedure according to Claim 18 or 19th .

Images