DE1428110A1 - Compressor blading - Google Patents

Description

Compressor blading.

! »The connection is to a blading and in particular on a compressor bladder that increases the flow linrichtung ^ ufv / eisi., which is a whole tit of the blading form.

One of the problems encountered with axial flow compressors commonly used in jet engines is the Irobleni of the compressor stalling. Lie reasons this stalling and theoretical considerations are not entirely clear, but the stalling can usually be summarized in such a way is found daiü that Xompressorbesoriaufelung not oi.ü is able to generate the .Druckanstieg 25U which to operate smoothly it, is orderly. In other words, the air flow through the compressor is disturbed and this leads to pressure pulses and abrasion or stalling of the air flow through the compressor.

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This can lead to serious malfunctions in so-called section engines, or the like as a result of which the operation of the engine is throttled. Many devices are supposed to sleep either to stop the compressor from shutting down or to change this state To determine early enough so that appropriate steps can be taken, other solutions have been attempted, according to v. ^r which the stalling is shifted out of the operating range of the power plant. The invention relates to devices with which the last-mentioned solution can be achieved The appearance of the boundary layer is known per se and also occurs in compressor and turbine operation. Although the invention can also be applied to a turbine, the invention is mainly suitable for compressors, but the application of the invention is suitable not limited to compressors ". The invention is to be described below with reference to compressors. In a typical compressor, in which walls are formed by a housing and a hub, there are blades with T-shaped profiles that work in a king space between the walls. It is known that boundary layers have the tendency to retain air on the adjacent walls. This leads to a slow movement of low-energy air on these walls and thus hinders the uniform primary air flow to the blades.

It is an object of the invention to provide auxiliary blades for the rotor blades or stator blades of a compressor or turbine in order to. to move the boundary layer air or to displace it with energy. J QfVQ an 7/0 1 A 6 BAD ORiGiISiAL d

see, with the help eflv ^ el increase the secondary flow, "around the boundary layer into the main flow through the blades "move and rotate.

According to the invention, auxiliary blading for the rotor and ötatorcliauf an iloiiipresEors or a turbine YOT - see to the secondary flow between "adjacent blades to rotate and increase by flow steering vanes which extend into the channel between the blades and the like are arranged so that the secondary flow which flows past the concave surface of the blades is directed towards the convex surfaces of the adjacent blades These bending vanes can be provided both on the root parts and on the tip parts of the blades in order to direct the secondary flow radially inwards at the root part and radially outwards at the tip part lls be arranged between adjacent blades and extend radially like these.

In the figures of the drawing are exemplary embodiments of the invention shown. Ss show:

a schematic cross-sectional view of a compressor rotor,

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Pig. 2 shows a part of a pair of rotors, the Cross flow between the blades is shown,

Fig.3 is a plan view of Pig.2, seen τοη the line 3-3 of Pig "2 off,

Pig. 4 one of the pig. 2 corresponding view _} which shows the arrangement of ribs or shovel-like parts in the vicinity of the Ifabe,

Pig.5 a similar view, the other shovel-like or rib-like Facilities near the property and the tips of the turbine blade shows, these facilities are only provided on one side,

Pig.6 is a partial view of a further embodiment in which the rib-like parts are used between the blades and '

Pig.7 is a graph showing the effect of the rib-like parts on the stall characteristics of a conventional compressor. . '■ ■

Reference is first made to Pig.1. In this Pigur is schematic a compressor rotor is shown, which has a hub 10 and an outer housing 11. These two parts form an inner one and one from sere y / andung. Between these walls carries in the usual Vifeise the hub 1o a row of rotorsehauf a 12 and the housing 11 has corresponding stator blades 13, these The blades extend radially towards the opposite wall. In this way an annular air duct 14 is created for the air flow formed by the compressor, with the air at the right

end

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End exits with higher pressure.

Reference is now made to FIG. 2, which shows a pair of rotor blades, and the flow problems that occur in a compressor are to be explained on the basis of this figure. It should be noted that the discussion is carried out with reference to the Hotor blades and that the same reasons can also be given for the stator blades. Since the ßotor -üchaufein are usually arched wing parts, which, as shown in 'Fig.3, have convex and concave surfaces, normally two air currents occur. The first is the primary air flow which enters at the leading edge of each blade and which exits at the trailing edge, as indicated in Fig. 3 by the straight arrow. This air is compressed in the usual way to a higher pressure. The second flow is called the ßkunruirströmung; b and this secondary flow is the movement of the air, borrowed in the v / es, takes place perpendicular to the main flow. This secondary flow comes from the pressure fields that exist in the blades and from the low momentum level of the grease-proof medium. MLe shown in FIGS. 2 and 3, the convex blade surface is normally under a lower pressure than the concave surface, which is indicated by the minus sign. The concave surface has a higher pressure, which is indicated by the plus sign in both figures. Because of this pressure difference, the length of the boundaries of the walls of the. Channel acts, a secondary flow occurs from the area of higher pressure to the area of lower pressure

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a-uf, as indicated in FIGS. 2 and 3 by the curved arrows ... ".- .. ,, a-n. This flow occurs in the vicinity of the walls 10 and 11. Es it can be seen that the secondary flow ,, as _they will be indicated by 'the curved arrows in ili'ig 3, ine large ^e.,:. ^ uerkomponente comprises, whereas the deflection of the Ilauptluftütromes caused by the blades " , not such a big one; Has transverse component. This large transverse component leads to a stronger rotation and consequently to an increased linear supply to the boundary ocher medium with a low impulse level.

In l ^'l igur 2, the secondary flow is shown by arrows 15 °. This secondary flow transports the medium of the main flow along the concave upper surface to the property 10 and the housing 11, as shown by the arrows, and transports the boundary layer medium away from the property and from the housing and to the central part of the ring duct -Although along the convex lookout top! .lache. This leads to. a --iS / i mixture of brave brave η. The result of the rotation and the rotation is that the boundary layers are driven, so that there is a higher pressure rise over it. the compressor blading can be adjusted without the flow being stalled or the compressor stalling »

The invention is intended to increase the turning _; and the "mixing of the boundary layer in the main air flow are promoted. Through this amplification and mixing it is possible to generate a higher pressure increase per" compressor stage, which leads to -, - that for a given Compression ratio of a compressor with "Ml ^ λ _rv ^{909807 / n} -1 ^^ BAD ORIGINAL -

fewer stages can be used.

To zu'verstärken das'Drehen and to assist in mixing, the tr ^ gen lächenförmi beating with Strömungsrichtungsflügein or vanes 16 is provided, as shown in FIG. 4 These wing or blade-like parts 16, which can be flat, but are preferably curved as shown, are preferably arranged at right angles to the blades, either on the stator blades or on the rotor heap, so that the main separation, which is in the In the vicinity of the concave surface of the vane, it flows past and is “pushed towards the neighboring wall.” As Pig.4 shows, the vane 1 2 has a concave surface 17 and a convex surface 18. D ^ ie main air flow, shown by the arrow 19, which generates secondary flow shown in FIG _o 2, by the blade pressure surfaces, 16 so arranged, the wing or hip on the blade 12 or oriented such that the secondary air flow, as shown in Pig .4, flows down on the concave surface and flows radially outwards or upwards on the convex surface of the adjacent show. The wing or rib 16 is disposed at substantially right angles on the vane 12 to promote flow in that direction. Since the natural secondary flow occurs in this direction, the wing or rib-like ropes mainly reinforce this flow and can even reverse the flow if the natural secondary flow is reversed. Since the medium with low momentum is the boundary medium, the wings or ribs at radial locations 1'-W "'-it-r ochoufcl 12 are essentially on the surface of the

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Boundary layer - the adjacent wall and consequently the wall adjacent, arranged. As Fig.4 shows, the hill is 1 6 arranged on the surface of the boundary layer at the flange or hub, Io. This is, as Fig.4 shows, the root part of the Rotors shovel 12. In the same way it is possible that ribs or wings 1 6 are provided on the tip parts of the rotor blade are. This training is shown in Fig.5, with one additional rib 2o is provided at the tip of the rotor blade in the vicinity of the housing 11. The stall properties of the special compressor determine the arrangement of the rib and wing-like ropes. When stall occurs at the tip portions of the rotor blades, a rib 2o used to keep the secondary air flow close. outside to judge. If the stall occurs at the root part, the rib may. 16 used to control the secondary air flow pointing inward and, if flow stall occurs in both places, either rib or wing can be used are mirror images of each other. Figure 5 shows the Use of vanes or ribs on only one side of the rotor blade »It may not be necessary to have the Provide wings or ribs on both sides of the turbine blade. In addition, various configurations can be provided. In the embodiment shown in Figure 4 is a curved Rib or arched wing is provided that extends in front of the leading edge the shovel extends. In the embodiment shown in FIG. 5, the wing or the rib extends in the essentially from the leading edge to the trailing edge. This export

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form allows application in a multi-level or multi-stage compressor. In all circumstances, the ribs or vanes on the concave surfaces are provided to keep the flow flowing from the higher pressure concave surface

to support and reinforce the adjacent, lower-pressure convex surface.

The wings or ribs can, as! Fig. 5 shows, both on the Yfurzel- as well as on the tip parts can be provided in order to direct the flow to the adjacent wall, which forms a boundary layer having. Since the wing or rib is located substantially on the surface of the boundary layer, the term is "Adjacent wall" is to be understood to mean that this is the wall on which the next-lying boundary layer is present.

Reference is now made to FIG. Fig. 6 shows another Embodiment, - the wing 21 being attached to the inner or outer Yifandungteil or to both wall parts can. As an exemplary embodiment, a wing 21 is shown which is attached to the hub 1o. To get the flow as desired reinforce, a member 21 with airfoil extends radially into the air duct H between the blades. Through this, that the member 21 is oriented at a certain angle of attack, the secondary flow can be increased. Fig. 6 shows how a such reinforcement takes place. If the wing 21 is not present, an air particle follows on the concave or plus side the shovel 12 a path indicated by the arrow and the line 22 is shown. When this air flea is along the labe to the

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adjacent blade 12 moved towards. If the wing 21 is like is arranged and aligned, the same particle follows the path shown by arrows and lines 23. The particle gets to the convex negative first Surface of the blade 21 and to the convex surface of the blade 12. The particle has been given a greater rotation and this leads to an increased supply of energy to the border layer and this results in better mixing and an increase in the secondary flow.

7 shows the results of the application of the rib-like or vane-like parts and it can be seen that when the percentage of the wing is increased, a higher pressure increase is reached _s before there will be a flow separation or stalling of the compressor. In other words, the use of the wing-like parts allows the stall point of a given compressor to be shifted beyond the operating range. The use of the wing-like or rib-like parts changes the usual pressure profile and creates a greater velocity gradient in order to transfer energy more quickly from the main flow to the boundary layer, whereby a greater pressure increase per compressor stage can be achieved. The rib-like or wing-like parts shown in Fig. 4 are curved and those shown in Fig. 5 are flat. A curved embodiment is preferably used, since this enables a stronger effect with lower losses. Furthermore, it is desirable that the wing-like or rib-like parts are provided at least on the concave surface of the blades, as shown in FIG. 5, in order to achieve the desired results.

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Claims (7)

¹¹ U28I10 Claims ^ί "Ί \. Auxiliary blades for the rotor or stator blades of a compressor or a turbine, which serve to amplify and rotate the secondary flow between" adjacent blades, characterized in that flow direction blades are provided for the blades, which are in the channels between extend into the blades and which are arranged such that the secondary flow which takes place near the concave surface of the blades is directed towards the convex surface of the adjacent blades. 2. Auxiliary vane according to claim 1, characterized in that the flow direction vanes are substantially radially on the blades are arranged on the surfaces of the boundary layers. 3. Auxiliary wing according to claim 1 or 2, characterized in that the flow direction wing on the blades on the fftzrzelteile or are arranged on the tip parts. 4. auxiliary wing according to claim 1, 2 or 3, characterized in that the flow direction wing both at the root as well are arranged at the tip parts of the blades to prevent the secondary flow radially inward at the Yi root and radially to be directed outwards at the tip parts. 5. auxiliary wing according to claim 2, 3 or 4, characterized in that the flow direction wings on the blades in the essential 90Ö807 / GU6 essentially.en from the leading edge to the trailing edge of the bucket extend and that the flow direction vanes are curved. 6. auxiliary wing according to claim 1, characterized in that the Flow direction vanes arranged between "adjacent blades are and extend radially. 7. auxiliary wing · according to claim 6, characterized in that the Flow direction vanes are airfoil-like parts; 909 8 0 7/014