DE102020115734B4 - Device, system and method for investigating the flow around turbine blades with supersonic outflow - Google Patents

Abstract

In order to simplify the investigation of the flow around turbine blades with supersonic exhaust, a device for investigating the flow around turbine blades with supersonic exhaust, 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 apart 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 bounded by a fluid-permeable partition, the device having a second flow path having an inlet and an outlet wherein the second flow path is separated from the flow path outlet section by the separating element, wherein the device has a secondary flow path, wherein the secondary flow path fluidly connects the flow path inlet section and the second flow path with one another, the secondary flow path being delimited by the first profile body, which is furthest away 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 exhaust 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 apart 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 partition element.

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

In addition, the present invention 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, 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 each other 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 of a fluid-permeable Separating element is limited.

It is known to use devices and systems of the type described above 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 profile row of the turbine stages or the compressor stages, which differ only slightly in shape, using a model-like device of the type described above.

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

A linear airfoil cascade consists of a finite number of airfoils that correspond in profile to the turbine blades, and accordingly the airfoil cascade must have some kind of termination that is a boundary condition for the flow. This conclusion is formed by the separating element. As a result, however, a flow angle is specified for the outflow away from the profile body cascade, which is not necessarily identical to the outflow in a turbine stage. Shock waves occurring in the flow are reflected at the separating element and thus falsify the measurements and observations.

However, alternative devices that are used do not have a separating element as a closure, but rather allow the outflow to expand into a free space at its end. However, the form or shape of this space and its exact pressure conditions are decisive for the degree of expansion. It must 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 exit of the flow from the profile body cascade and the specified boundary condition become so great that the strength of the reflected compression shocks is significantly reduced by diffusion. 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.

Furthermore, it must be taken into account that when the device is checked numerically, the problem arises that a boundary of the profile body cascade at the flow outlet is neither completely an inflow nor an outflow. This makes correct numerical modeling of such boundary conditions difficult.

In principle, it would be possible to examine 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 is also necessary in this case. In addition, the curvature makes it very difficult to use imaging methods to examine the flows. at For example, the so-called Schlieren technique for imaging can only be implemented here with great effort.

From the CN 104677638A a device for examining the flow around turbine blades is known. In AIAA 2003-455, 41st Aerospace Sciences Meeting and Exhibit, 6-9 January 2003, Reno, Nevada, A. Rona et al. "Wall interference in the discharge flow in a linear cascade wind tunnel" describes wall interference in a flow exiting from a linear cascade wind tunnel.

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

In a device of the type described at the outset, this object is achieved according to the invention 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 fluidly connects the flow path inlet section and the second flow path with one another, 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, which runs parallel or essentially parallel to the separating element.

Developing a device of the type described at the outset in the proposed manner has the particular advantage that, despite the use of the separating element, a flow situation can be achieved 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 Cascade into free space comes very close. The profile body cascade is also referred to below as the blade cascade or turbine blade cascade. A row of blades is in particular a complete ring of blades in a turbine or a compressor. In principle, a circular cascade corresponds to a row of blades, but is part of a test bench and not part of a turbomachine. The second flow path runs in particular parallel or substantially parallel to the outflow direction of the fluid flow away from the profile body cascade. In particular, the same pressure can be present at the inlet and at the outlet of the second flow path, for example atmospheric pressure. Due to the fact that part of the fluid flow flowing through the first flow path is guided through the secondary flow path, a 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, when the separating element is designed to be fluid-permeable, the reflection of compression shocks in the outflow of the profile body cascade on the separating element can be prevented, specifically in that a local excess of fluid is diverted through the separating element into the second flow path. Thus, in particular, a precise definition of the boundary condition is possible. An additional effort, which arises from a side space of whatever design, in which a pressure has to be controlled and/or regulated in a defined manner, is eliminated in this way. 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 be created in particular on a surface of the separating element facing the profile body cascade. In known devices, control of the pressure in the side space separated by the separating element from the flow path outlet section has hitherto been required in order to achieve effective shock reduction without unduly disturbing the flow to be observed. In other words, the design of the proposed secondary flow path and its alignment make it possible to dispense with pressure control in the space delimited by the separating element with a side face pointing away from the profile body cascade. This simplifies the structure of the device. Furthermore, the execution of the examinations is also simplified.

It is favorable if a side face of the first profile body facing away from the fluid inlet delimits the second flow path. This side surface facing away, 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 is created in the second flow path, which allows part of the fluid flow flowing through the flow path outlet section to pass through the separating element and possibly 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 simplifies the structure of the device.

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 that face 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 using Schlieren technology.

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

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

It is favorable if the separating element is arranged adjacent to a profile body end of the first profile body pointing in the direction of the fluid outlet. In this way, in particular, a simple separation between the fluid flow in the second flow path and in the flow path outlet section can be achieved. The only connection between the first and second flow path is thus realized through 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 only serves as a device to prevent the reflection of compression shocks, as already explained above, by draining 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 specified 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 profile body side surfaces of the profile bodies 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, with 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 pointing in the flow direction of the profile bodies.

The profile bodies can be formed in a simple manner if 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 substantially 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 and supersonic flows with only a small proportion of velocity towards the wall are also made possible. The separating element itself therefore does not specify a flow angle.

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 advantageously 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 delimitation surface located opposite the separating element. This makes it possible, in particular, for a fluid to flow through the second flow path only through the inlet and out again through the outlet.

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

According to a further preferred embodiment of the invention, it can be provided that the boundary surface is designed to be adjustable in order to adjust an angle enclosed between the separating element and the boundary surface. In this way, in particular, a fluid flow through the second flow path can 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. Alternatively, of course, it is also possible to design the profile bodies differently. For example, in the case of turbines, turbine blades can be provided in two different forms, which are arranged alternately and flow around them.

In order to be able to use the device to simulate an outflow of an endless cascade as well as possible, it is favorable if the number of profile bodies in 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 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 about 5° to about 30°. In particular, it can be in a range from about 10° to about 20°. Providing opening angles in the specified ranges makes it possible, in particular, to realize a boundary condition with the separating element in connection with the second flow path, which corresponds to or essentially 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 favorable if the separating element is designed to be adjustable in order to set the opening angle. This makes it possible to carry out 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 flat or essentially flat. Such a separating element can be formed in a simple manner, for example from a plate.

Furthermore, it can be advantageous, especially in a device of the type described above, if the separating element has a plurality of openings. The separating element is therefore designed 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 drained off through the openings in the separating element into the second flow path in order to avoid unwanted reflections. In particular, the separating element can have a surface structure, for example a three-dimensional one, on a second side surface which points away from the profile body cascade. For example, the separating element can have a plurality of depressions on the second side surface pointing away from the profile body cascade, in particular in the area of the openings. Such a configuration facilitates the drainage of the local excess of fluid generated by compression shocks through the openings. In particular, it is advantageous if the separating element with the plurality of openings is designed in such a way that all edges, in particular the edges delimited by the openings, are designed with sharp edges and are not rounded. In this way, a clean separation can be achieved and, in particular, reflections in the area of edges that delimit the openings can be prevented.

The plurality of openings is preferably designed in the form 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 conduct compression shocks originating 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 structured in a three-dimensional manner in a simple manner if the plurality of openings widens conically in the direction of the second flow path. In particular, funnel-shaped depressions are thus 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 openings is in a range from approximately 90° to approximately 150°. In particular, the cone angle can be in a range from about 110° to about 130°. Such cone angles make it possible, 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 formed in a simple manner with standard spiral or countersink drills with an end angle corresponding to this cone angle

It is favorable if the plurality of openings 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 is quite possible that not every opening is surrounded by six openings. This applies in particular to openings at the edge of the separating element. Nevertheless, the pattern is hexagonal if the openings are regularly arranged 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 openings is formed identically.

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

In particular for the production of the separating element, it is favorable if the longitudinal axis of the opening runs transversely to the separating element. In particular, it can run perpendicularly 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 encloses an opening angle with the separating element. Such a configuration can contribute in particular to further reducing reflections from compression shocks on the separating element.

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

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 condition with the separating element.

Preferably, a ratio of a total aperture area defined by the plurality of apertures relative to a total separator area is in a range of about 0.1 to about 0.5. The larger the ratio, the easier it is to prevent compression shocks from being reflected on the separating element.

Furthermore, it is 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 is, the more likely it is that compression shocks impinging on the separating element are sufficiently weakened in order to prevent unwanted reflection of the compression shocks as effectively as possible.

Conveniently, a ratio of the thickness to the diameter of the plurality of openings is in a range from about 0.1 to about 1. In particular, the ratio can be in a range from about 0.2 to about 0.6. Such a ratio has a particularly favorable effect on the stability of the separating element and the desired effect thereof, namely achieving 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 an area surrounding the device. In particular, this can 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.

In a system of the type described above, the object stated at the outset is achieved according to the invention 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, investigations into the flow around turbine blades with supersonic outflow can be carried out in a simple manner.

The configuration of the system can be simplified in particular in that the fluid source comprises a liquid gas reservoir and/or a compressed gas reservoir. Such fluid sources allow a fluid flow with a desired speed and in a simple manner provide a desired pressure before flowing through the profile body cascade.

The object set at the outset is also achieved according to the invention in a method of the type described at the outset 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 in the direction 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 fluidly connects the flow path inlet section and the second flow path with one another, that the fluid flow portion flows around the first profile body, which is furthest away from the fluid outlet, and that the fluid flow portion defines a secondary flow path outlet direction into the second flow path that is parallel or substantially parallel to the partition member.

As already explained above, the fluid flow portion that flows through the secondary flow path can generate a negative pressure corresponding to the flow speed of the fluid flow in the second flow path in order to facilitate the 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 guiding the secondary flow path appropriately, an optimal adjustment of the pressure conditions in the second flow path and in the flow path outlet section can be achieved purely geometrically. 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. A fluid flow can thus be made visible in a simple manner.

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

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

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 (110) 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 thus includes in particular the embodiments of devices, systems and methods for investigating the flow around turbine blades with supersonic outflow, defined below in the form of numbered sentences:

1. 1. 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 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), wherein adjacent profile bodies (24; 24a-24f) are spaced apart and a profile flow path section (72) define between them, 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) a flow path outlet section (82) and wherein the Flow path outlet section (82) is limited by a fluid-permeable separating element (96), characterized in that the device (12) has a second flow ngspfad (68) having 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) has that the secondary flow path (106) fluidly connects the flow path inlet section (80) and the second flow path (68) to one another, 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).
2. 2. Device according to clause 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).
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 wall surfaces (62, 64) pointing towards one another, in particular running parallel to one another.
4. 4. Device according to sentence 3, characterized in that the separating element is aligned transversely, in particular perpendicularly, to the wall surfaces (62, 64).
5. 5. Device according to sentence 3 or 4, characterized in that 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.
6. 6. Device according to one of the preceding sentences, characterized in that the separating element (96) is arranged on an end (94) of the first profile body (24a) pointing in the direction of the fluid outlet (20).
7. 7. Device according to one of the preceding sentences, 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).
8. 8. The device according to sentence 7, characterized in that the outlet direction is defined by or essentially by an alignment (76) of the profile body side surfaces (74) of the profile bodies (24a-24f) facing away from the fluid inlet (18) relative to the inlet direction (70).
9. 9. The device according to sentence 8, characterized in that the profile body side faces (74) facing away from the fluid inlet (18) are flat or essentially flat.
10. 10. Device according to one of sentences 7 to 9, characterized in that the separating element (96) is arranged to run parallel or substantially parallel to the outlet direction (76).
11. 11. Device according to one of the preceding sentences, characterized in that the second flow path (68) defines a flow direction (110) which runs in a straight line or essentially in a straight line.
12. 12. Device according to one of the preceding sentences, characterized in that the second flow path (68) runs parallel or substantially parallel to the separating element (96).
13. 13. Device according to one of the preceding sentences, characterized in that the second flow path (68) is delimited by a fluid-impermeable delimitation surface (102) lying opposite the separating element (96).
14. 14. Device according to sentence 13, characterized in that the boundary surface (102) runs parallel or essentially parallel to the separating element (96).
15. 15. The device according to sentence 13 or 14, characterized in that the boundary surface (102) is designed to be adjustable for adjusting an angle (112) enclosed between the separating element (96) and the boundary surface (102).
16. 16. Device according to one of the preceding sentences, characterized in that all profile bodies (24a-24f) are of identical design.
17. 17. Device according to one of the preceding sentences, characterized in that 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 from 6 to 10.
18. 18. Device according to one of the preceding sentences, characterized in that profile body ends (94) of the profile bodies (24a-24f) define a common profile body end surface (114), in particular a plane (116), and in that the profile body end surface (114) and the separating element ( 96) enclose an opening angle (118).
19. 19. Device according to sentence 18, 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. The device according to sentence 18 or 19, characterized in that the separating element (96) is designed to be adjustable for adjusting the opening angle (118).
21. 21. Device according to one of the preceding sentences, characterized in that a first side surface (98) of the separating element (96), which faces the profile body cascade (22), is flat or essentially 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) has a plurality of openings (120).
23. 23. Device according to sentence 22, characterized in that the plurality of openings (120) is nozzle-shaped.
24. 24. The device according to sentence 22 or 23, characterized in that the plurality of Openings (120) in the direction of the second flow path (68) widens conically.
25. 25. Device according to sentence 24, characterized in that a cone angle (122) of the plurality of openings (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 clauses 22 to 25, characterized in that the plurality of openings (120) are arranged in a regular or an irregular pattern.
27. 27. The device according to clause 26, characterized in that the plurality of apertures (120) are arranged in a hexagonal pattern, in which pattern each aperture (120) is surrounded by six apertures (120).
28. 28. Device according to one of sentences 22 to 27, characterized in that the plurality of openings (120) is of identical design.
29. 29. The device according to one of sentences 22 to 28, characterized in that the plurality of openings (120) are each formed rotationally symmetrically in relation to a longitudinal axis (124) defined by the respective opening (120).
30. 30. The device according to sentence 29, characterized in that the longitudinal axis (124) of the opening runs transversely, in particular perpendicularly, to the separating element (96).
31. 31. The device according to sentence 29 or 30, characterized in that the longitudinal axis (124) of the opening is inclined in the direction of the outlet (28) and encloses an opening angle with the separating element (96).
32. 32. Device according to one of sentences 22 to 31, characterized in that the plurality of openings (120) is in the form of bores (128).
33. 33. Device according to one of sentences 22 to 32, characterized in that a minimum diameter (130) of the plurality of openings (120) is in a range from about 0.5 mm to about 2.1 mm, in particular in a range of about 1.0 mm to about 1.6 mm.
34. 34. Apparatus according to any one of clauses 22 to 33, characterized in that a ratio of a total aperture area defined by the plurality of apertures (120) relative to a total separator area is in a range of about 0.1 to about 0.5.
35. 35. Device according to one of the preceding sentences, characterized in that the separating element (96) has 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) of the plurality of openings (120) is in a range from about 0.1 to about 1, in particular in a range of about 0.2 to about 0.6.
37. 37. Device according to one of the preceding sentences, 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).
38. 38. A system (10) for investigating the flow around turbine blades with supersonic exhaust, which system (10) comprises an apparatus (12) according to any one of the preceding sentences and a fluid source (14) for generating a fluid flow, the fluid source (14) and the fluid inlet (18) are fluidly connected to each other.
39. 39. System according to sentence 38, characterized in that the fluid source comprises a liquid gas reservoir (34) and/or a compressed gas reservoir (42).
40. 40. 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), wherein adjacent profile bodies (24; 24a-24f) are arranged at a distance from one another and one Define profile flow path section (72) between them, wherein the first flow path (66) between the fluid inlet (18) and the profile body cascade (22) a flow path inlet section (80) and between the profile body cascade (22) and the fluid outlet (20) a flow path outlet section (82) defined, wherein the flow path outlet section (82) is bounded by a fluid-permeable partition member (96), characterized in that d ass a fluid flow portion (136) of the first fluid flow (134) from the flow path inlet section (80) through a secondary flow path (106) into a second flow path (68) with a inlet (26) and an outlet (28) in order to generate a free jet in the second flow path (68) in the direction of the outlet (28) in the direction of the second flow path (68) from the flow path outlet section (82) through the separating element (96 ) is separated, that the secondary flow path (106) fluidly connects the flow path inlet section (80) and the second flow path (68) to one another, that the fluid flow portion (136) touches the first profile body (24a), which is furthest away from the fluid outlet (20), flows around and that the fluid flow portion (136) defines a secondary flow path outlet direction (108) into the second flow path (68) that runs parallel or substantially parallel to the separating element (96).
41. 41. The method according to sentence 40, characterized in that Schlieren images of the fluid flow flowing through the profile body cascade (22) are recorded.
42. 42. The method according to sentence 40 or 41, characterized in that the second flow path (68) is fluidically connected to an environment (30).
43. 43. Use of a device (12) according to one of sentences 1 to 37 or of a system (10) according to sentence 38 or 39 for carrying out a method according to one of 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 more detailed explanation. Show it:

• 1 1 is a schematic representation of an embodiment of a system for investigating the flow of turbine blades with supersonic exhaust;
• 2 1: a schematic representation of a further exemplary embodiment of a system for investigating the flow around turbine blades with supersonic outflow;
• 3 : a schematic perspective view of a device for investigating the flow around turbine blades with supersonic outflow, which is part of the in 2 illustrated embodiment of a system forms;
• 4 : a plan view of the assembly 3 in the direction of arrow A;
• 5 : a view of the arrangement 4 in the direction of arrow B;
• 5A : an enlarged view of the C portion 5 ;
• 6 1: a schematic plan view of a separating element on its side surface pointing away from the profile body cascade;
• 7 : a sectional view taken along line 7-7 in 6 ;
• 8th : a background schlieren image of a flow test with the exemplary embodiment of a system shown in FIG.
• 9 : another background schlieren image of a flow test;
• 10 1: an illustration 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 separator; and
• 12 : a representation of the result of a CFD calculation analogous 10 , but with a perforated divider with a hole diameter of 1.3 mm.

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

The system 10 includes an apparatus 12 for investigating the flow around turbine blades with supersonic exhaust and a fluid source 14 for generating a fluid flow. The fluid source 14 is fluidly connected to a fluid inlet 18 of the device 12 via a connecting line 16 .

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

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

2 FIG. 1 shows a further exemplary embodiment of a system for investigating the flow around turbine blades with supersonic outflow, which system is also denoted overall by reference numeral 10 . The device 12 shown schematically in box 32 is in 2 enlarged on the right and shown with a higher level of detail.

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

The tank 34 is fluidly connected to the fluid inlet of the device 12 via the connecting line 16 . A valve 36 is arranged in the connecting line 16 in order to adjust the flow of liquid nitrogen through the connecting line 16 into the device 12 .

The tank 34 is fluidically connected to a further tank 42 via a further connecting line 38 in which a valve 40 is arranged. The tank 42 has a volume of 10 m ³ and is filled with gaseous nitrogen and a pressure of 20 MPa.

A pump 44 for conveying liquid nitrogen is fluidically connected to an evaporator 48 via a connecting line 46 . The evaporator 48 is in turn fluidically connected to the tank 42 via a connecting line 50 .

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

The structure of the device 12 is described below in connection with the 2 until 7 explained in more detail.

The fluid flowing into the device 12 first passes from the connecting line 16 into an antechamber 52. The antechamber 52 is open at the side and is coupled to the fluid inlet 18 of the device 12 in a fluid-tight manner.

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

Facing side surfaces 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 formed.

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

Adjacent airfoils 24a-24f are spaced apart and define airfoil flow path portions 72 therebetween.

The profile bodies 24a-24f have a cross-sectional view, as shown schematically in 4 is shown, a streamlined profile with a flat, facing away from the fluid inlet 18 profile body side surfaces 74 which are flat or substantially flat.

The profile body side faces 74 of the profile bodies 24a-24f point in the direction of the fluid outlet 20 parallel to an outlet direction 76 indicated by an arrow.

The inlet direction 70 of the fluid inlet 18 and the outlet direction 76 of the fluid outlet 20 enclose a deflection angle 78 which has a value of approximately 105° in the exemplary embodiment described.

The first flow path 66 defines 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. The flow path inlet section 82 is defined both by the wall surfaces 62 and 64 and by two wall surfaces 84 and 84 facing one another 86 which are perpendicular to the wall surfaces 62 and 64 and parallel to one another and to the inlet direction 70 .

The wall surface 84 ends with its end pointing towards the profile body cascade 22 at a curved guide surface 88, the shape of which corresponds to a profile body side surface 90 of the profile bodies 24a-24f pointing in the direction of the fluid inlet 18.

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

An end of the wall surface 86 pointing away from the fluid inlet 18 adjoins a guide surface 92 whose shape corresponds to the side surface 74 of the profile body.

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

The flow path outlet section 82 is delimited opposite the profile bodies 24b-24f by a separating element 96 which is designed to be permeable to fluid and is described in more detail below.

The separating element 90 has a first side surface 98 which points in the direction of the profile bodies 24b-24f. A second side surface 100 of the separating element 96 points away from the profile body cascade 22 and delimits the second flow path 66.

A fluid-impermeable boundary surface 102 , which extends from the inlet 26 to the outlet 28 , runs parallel to the separating element 96 . Parallel to the boundary surface 102, a boundary surface 104 extends from the inlet 26 to the profile body end 94 of the guide surface 88.

As described, the separating element 96 separates the second flow path 68 from the flow path outlet section 82.

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

The secondary flow path 106 is delimited by the profile body 24a, which forms a first profile body 24a, which is at the furthest distance from the fluid outlet 20.

The shape of profile flow path section 72, which forms secondary flow path section 106, defines a secondary flow path outlet direction 108, symbolized by an arrow, which is directed into second flow path 68 and runs parallel or essentially parallel to separating element 96.

The profile body side surface 74 of the first profile body 24a facing away from the fluid inlet 18 delimits the second flow path 68, as described.

The separating element 96 is arranged adjacent to the profile body end 94 of the first profile body 24a pointing in the direction of the fluid outlet 20 .

The second flow path 68 defines a flow direction 110 , symbolized by an arrow, which is directed parallel to the outlet direction 26 . This makes it possible for fluid flowing through the flow path outlet section 82 and the second flow path 68 to flow out together through the fluid outlet 20 and the outlet 28 which is only separated from it by the separating element 96 . The separating element 96 is thus arranged parallel or essentially parallel to the outlet direction 76 .

The second flow path 68 described specifies the direction of flow 110 in a straight line or running essentially in a straight line. 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 is designed to be adjustable in order to adjust an angle 112 enclosed between the separating element 96 and the boundary surface 102. In the embodiment illustrated in the figures, the angle 112 is 0°, because that Separating element 96 and the boundary surface 102 run parallel to one another.

In alternative exemplary embodiments, the cascade of profiled bodies 22 can also include a different number of profiled bodies 24, with the number being in a range from 4 to 15, for example.

The scoop ends 94 of the scoops 24a-24f define a common scoop end surface 114 which contacts them and defines a plane 116 in the embodiment shown in the figures. This profile body end surface 114 or the plane 116 on the one hand and the separating element 96 on the other hand define an opening angle 118 between them, which has a value of approximately 14° in the exemplary embodiment illustrated in the figures, i.e. in a range from approximately 5° to approximately 30° .

In an exemplary embodiment not shown in the figures, the separating element 96 is designed to be adjustable in order to vary or set the opening angle 118.

The first side surface 98 of the separating element 96 is flat or essentially flat.

The second side surface 100 of the separating element 96 has a three-dimensional structure, which will be explained in detail below.

6 shows a schematic plan view of the side surface 100 of the separating element 96.

The separating element 96 has a plurality of openings 120 which are designed in the form of nozzles. The openings 120 widen conically from the first side surface 98 to the second side surface 100 , thus in the direction of the second flow path 68 .

A cone angle 122 of the openings 120 is approximately 118° and is therefore in a range from approximately 90° to approximately 150°.

As exemplified in 6 as can be seen, the plurality of openings 120 is arranged in a regular pattern. This pattern is a hexagonal pattern in which each opening 120 is surrounded by six further openings 120 .

In the embodiment shown in the figures, the openings 120 are identical.

The openings 120 are each formed rotationally symmetrically in relation to a longitudinal axis 124 defined by the respective opening 120 . The longitudinal axis 124 of the opening runs transversely, in the exemplary embodiments illustrated in the figures perpendicularly, to the separating element 96 or to a central plane 126 defined by it.

In a further exemplary embodiment, the longitudinal axis 124 of the opening is inclined in the direction of the outlet 28 and encloses an opening angle with the separating element 96 .

The plurality of openings 120 is in the form of bores 128 .

A minimum diameter 130 of the openings 120 is 1.3 mm and is therefore in a range from approximately 0.5 mm to approximately 2.1 mm.

The plurality of apertures 120 collectively define an overall aperture 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 or 100, is in a range from approximately 0.1 to approximately 0.5 in the exemplary embodiment described.

In the exemplary embodiments described, the separating element 96 has a thickness 132 of approximately 4 mm, ie in a range from approximately 0.3 mm to approximately 1 mm.

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

As already mentioned, the inlet 26, the outlet 28 and the fluid outlet 20 open into an environment 30 of the device 12.

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

A fluid flow portion 136 of the first fluid flow 134 is directed from the flow path inlet section 80 through the secondary flow path 106 into the second flow path 68 in order to generate a free jet in the second flow path 68 in the direction of the outlet 28 .

Due to the transparent design of the plates 54 and 56, it is possible to record Schlieren images of the fluid flow flowing through the profile body cascade 22 .

To carry out flow tests, the pressure prevailing in the antechamber 52 is increased up to a desired pressure ratio. Gaseous fluid now flows into the device 12 through the inlet 18 . A gas stream from the environment is also entrained by the provided secondary flow path 106 and flows through the second flow path 68 from the inlet 26 to the outlet 28 . Environment 30 may be open to outside air in one embodiment. This is possible when an outlet pressure of 1 atm is desired and the test gas is air or a comparable gas such as nitrogen.

the 8th and 9 12 show images of the results of a flow investigation using the device 12 described. These images clearly show that the fluid flow is influenced in the direct vicinity of the separating element 96, but this is affected with increasing distance voltage subsides quickly. However, the influence in the area of the 8th and 9 shown profile flow path sections 72 to be clearly distinguished from the actual flow phenomenon to be observed.

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

The supersonic flow lies against the first side surface 98 of the separating element 96 . Considering a single streamline that strikes the structure defined by the apertures 120 at an acute angle, depending on the precise location at which it strikes, it may either be redirected to be tangent or substantially tangential to the first face 98, or redirected to be expanded through an opening 120 into the second flow path 68 . In the first case, a compression shock is generated, in the second case, an expansion fan. Since 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, these phenomena are almost completely eliminated and the influence on the distant flow is very small. The prerequisite for this is, in particular, that a velocity component of the fluid flow in the flow path outlet section 82 in the direction normal to the side surface 98 is relatively small, i.e. the flow runs almost parallel to the separating element 96 or its first side surface 98 .

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

10 shows an ideal outflow of the profile body cascade 22. The profile body cascade is assumed here as an infinite cascade. An outflow takes place here in an unlimited space, so that no reflections of compression shocks 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 12 shows the same infinity cascade with outflow, however, the impenetrable boundary surface 102 is replaced by a partition element 96. FIG. As can be clearly seen, the flow with the separating element is far more similar to the ideal infinite cascade than the arrangement with the flow conditions shown in 11 are shown. Impact reflections from separator 96 are greatly reduced compared to impenetrable boundary surface 102 . This makes it possible to create a periodic flow with the separating element 96, 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 taken. In addition, the degree of expansion is influenced significantly less by the partition element than by an impermeable boundary surface 102.

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

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

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

Reference List

10

system

12

contraption

14

fluid source

16

connection line

18

fluid inlet

20

fluid outlet

22

profile body cascade

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

profile body

26

inlet

28

outlet

30

vicinity

32

Crate

34

tank

36

Valve

38

connection line

40

Valve

42

tank

44

pump

46

connection line

48

Evaporator

50

connection 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

airfoil flowpath section

74

profile body side 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 side face

92

guide surface

94

profile body end

96

separator

98

first face

100

second side face

102

boundary surface

104

boundary surface

106

bypass flow path

108

secondary flow path outlet direction

110

flow direction

112

angle

114

profile body end face

116

level

118

opening angle

120

breakthrough

122

cone angle

124

breakthrough longitudinal axis

126

midplane

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), 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 apart 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) 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 s path (68) having an inlet (26) and an outlet (28), that the second flow path (68) from the flow path outlet section (82) through the separating element (96), that the device (12) has a secondary flow path (106), that the secondary flow path (106) fluidly connects the flow path inlet section (80) and the second flow path (68) to one another, that the secondary flow path (106) is separated from 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 is parallel or essentially parallel to the separating element (96 ) runs. device after claim 1 , characterized in that a fluid inlet (18) facing away from the side surface (74) of the first profile body (24a) 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) pointing towards one another, in particular running parallel to one another. device after claim 3 , characterized in that a) the separating element is aligned transversely, in particular perpendicularly, to the wall surfaces (62, 64) and/or b) the wall surfaces of side surfaces (58, 60) are transparent in the visible spectral range of plates (54, 56), in particular Plastic plates or glass plates are defined. Device according to one of the preceding claims, characterized in that the separating element (96) is arranged adjoining 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 after claim 6 , characterized in that a) the outlet direction is defined by or essentially by an orientation (76) of the profile body side faces (74) of the profile body (24a-24f) facing away from the fluid inlet (18) relative to the inlet direction (70), wherein in particular 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 running 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 flow direction (110) which runs in a straight line or essentially in a straight line, and/or b) runs parallel or essentially parallel to the separating element (96). and/or c) is delimited by a fluid-impermeable delimitation surface (102) opposite the separating element (96), wherein in particular the delimitation surface (102) runs parallel or essentially parallel to the separating element (96) and/or is designed to be adjustable in order to adjust 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 of identical design 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 approximately 5° to approximately 30°, in particular in a range from approximately 10° to approximately 20°, and/or d) a first side face (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 after 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 in particular a cone angle (122) of the plurality of openings (120) is in a range from approximately 90° to approximately 150°, in particular in a range from approximately 110° to approximately 130°, and/or c) the plurality of openings (120) in is arranged in a regular or an irregular pattern, in particular the plurality of openings (120) being arranged in a hexagonal pattern, in which pattern each opening (120) is surrounded by six openings (120), and/or d) the plurality of Perforations (120) is formed identically. device after claim 10 or 11 , characterized in that the plurality of openings (120) is formed in each case rotationally symmetrically in relation to a longitudinal axis (124) defined by the respective opening (120). device after claim 12 , characterized in that the longitudinal axis (124) of the opening runs a) transversely, in particular perpendicularly, to the separating element (96) and/or b) is inclined in the direction of the outlet (28) and encloses an opening angle with the separating element (96). Device according to one of Claims 10 until 13 , characterized in that a) the plurality of openings (120) is 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 to about 2.1 mm, in particular 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) relative to a total area of the separating element in one area from about 0.1 to about 0.5. 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, with in particular a ratio of the thickness (132) to the minimum diameter (130 ) of the plurality of openings (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. 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 exhaust, which system (10) comprises an apparatus (12) according to any one of the preceding claims and a fluid source (14) for generating a fluid flow, the fluid source (14) and the Fluid inlet (18) are fluidly connected to each other, in particular the fluid source comprises a liquid gas reservoir (34) and / or a compressed 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), wherein adjacent profile bodies (24; 24a-24f) are arranged at a distance from one another and a profile flow path section ( 72) between them, 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), the flow path outlet section (82) being delimited by a fluid-permeable partition element (96), characterized in that a fluid flow portion (136) of the first fluid flow (134) is directed from the flow path inlet section (80) through a secondary flow path (106) into a second flow path (68) having an inlet (26) and an outlet (28) to generate a free jet in the second Flow path (68) towards 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) has the flow path inlet section (80) and the second flow path (68) in a fluid-effective manner, that the fluid flow portion (136) flows around the first profile body (24a), which is furthest away from the fluid outlet (20), and that the fluid flow portion (136) has 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 after Claim 18 , characterized in that a) Schlieren images of the fluid flow flowing through the profile body cascade (22) are recorded and/or b) the second flow path (68) is fluidically connected to an environment (30). Use of a device (12) according to one of Claims 1 until 16 or a system (10) after Claim 17 to carry out a procedure Claim 18 or 19 .

Images