RU2565138C1 - Turbojet low-pressure compressor rotor impeller blade - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: claimed blade of low-pressure compressor impeller disc of turbojet with flow channel confined in peripheral outline by engine housing comprises root and butt. Said blade can be fitted in whatever groove of the first stage impeller disc. Blade butt has lengthwise axis aligned or parallel with the disc groove geometrical axis and makes with rotor axis in projection on arbitrary axial plane perpendicular to the blade root radial axis the blade pitch angle α₀ that equals α₀ = (17÷27)°. Blade root features axis twist increasing at radial spacing from the rotor shaft axis with the root twist gradient G_r.t. defined in projection on axial plate to make (124.0-186.8) [degree/m]. Blade root has side edges diverging to peripheral end with the chord increase gradient G_c.i. making (7.2-10.7)·10^-2 [m/m].

EFFECT: improved geometrical configuration, spatial stiffness, structural and aerodynamic parameters, higher efficiency and expanded range of the compressor gas-dynamic stability, longer life of the blade.

5 cl, 4 dwg

Description

The invention relates to the field of aircraft engine manufacturing, and in particular to low-pressure compressors of aircraft turbojet engines.

Known profiled compressor blade for the impeller disk having axial, tangential and radial orthogonal axes, containing high and low pressure sides, extending in the radial direction from the shank to the apex and in the axial direction between the front and rear edges, cross sections having corresponding chords and bending lines extending between the leading and trailing edges, and centers of gravity aligned along a pivot axis having a double bend. The low pressure side is curved along the trailing edge near the liner to reduce the separation of the flow on it (RU 2000130594 A, publ. 01.27.2003).

Known compressor blades, including a feather and a shank. The shank of the blade is located horizontally, and the feather is connected to the shank through an intermediate element - the leg. Between the leg and the feather there is a shelf forming the engine’s flow part (NN Sirotin, A. S. Novikov, A. G. Paykin, A. N. Sirotin. Fundamentals of designing the production and operation of aircraft gas turbine engines and power plants in the CALS system technologies. Book 1. Moscow. Science 2011, pp. 257-263).

The disadvantages of the known solutions include the uncertainty of achieving effective interaction of the blades with the flow of the working fluid due to the lack of specification of the ranges of geometric and aerodynamic parameters of the spatial configuration of the pen and the angular installation of the blades in the impeller of the rotor, as well as the difficulty of obtaining a compromise combination of increased values of compressor efficiency, gas-dynamic stability (GDU) and as a result, the difficulty of providing optimal dynamic strength and increased resource shoulder blades.

The objective of the present invention is to develop the blades of the impeller of the first stage of the rotor of a low-pressure compressor of a turbojet engine with improved structural and aerodynamic parameters of the spatial configuration and stiffness of the feather blades, providing a compromise combination of increased values of efficiency, increasing the flow rate of the compressible working fluid - air in the first stage and air flow in the subsequent stages of the low pressure valve at all engine operating modes, as well as gasdynamic stability and resource without increasing the material consumption of the scapula.

The problem is solved in that the blade of the grooved disk of the impeller of the rotor of the low pressure compressor (KND) of the turbojet engine (TRD), including the flow part, limited along the peripheral contour of the engine housing, according to the invention contains a feather with a radial axis and a shank with a longitudinal axis and is intended for installation in any of the grooves of the disk of the impeller of the first stage, for which the shank of the blade has a longitudinal axis, coaxial or parallel to the geometric axis of the groove of the disk and forming with the axis of the rotor in the projection onto the conditional axial plane normal to the radial axis of the blade feather, the blade angle α ₀ , defined in the range α ₀ = (17 ÷ 27) °; in addition, the blade feather is made with an axial twist variable with respect to the rotor axis, increasing with a radial distance from the rotor shaft axis with a pen twist gradient G _zp defined in the projection onto said conditional axial plane in the range

G _s.p. = (α _p -α _k ) / L _cp = (124.0 ÷ 186.8) [deg / m],

where α _to is the projection of the angle of twist of the chord of the root section of the feather of the blade relative to the axis of the rotor in the conditional axial plane of the rotor normal to the radial axis of the blade; α _p - a similar projection of the swirl angle relative to the rotor axis of the most remote peripheral chord of the pen in a plane parallel to the axial plane; L _cp is the average axial length of the blade feather; moreover, the blade feather is made with lateral edges diverging to the peripheral end with a gradient of increasing chords G _yx ,

G _yx = (L _p.x -L _c.x ) / L _cp = (7.2 ÷ 10.7) · 10 ^-2 [m / m],

where L _p.x - the length of the peripheral chord connecting the edges of the feather blades; L _K.x - the length of the root chord connecting the edges of the feather blades in a conventional plane parallel to the axial plane of the rotor; L _cp - the average axial length of the feather blades.

In this case, the blade can be equipped with an anti-vibration shelf located in the region of one third of the length from the peripheral end of the feather of the blade and oriented along the flow of the working fluid, and each end of the indicated shelf can be mutually supported on the similar end face of the adjacent blade of the driving wheel facing it.

The blade feather can be made convex-concave, with a concave surface in the form of a trough endowed with a discharge function, and with a convex surface forming the back of the pen with the function of diluting the pressure and suction of the working fluid flow when the impeller rotates, in addition, a chord connecting the side edges pen in the root zone, forms with the rotor axis in the projection onto said notional plane angle of the stylus, substantially at least _{to the} setting angle α of the blade root.

The feather of the blade can be made variable in width and height of the feather thickness, defined in cross section as the difference between the heights of the back and trough relative to the conditional chord connecting the side edges of the feather blade.

The peripheral end face of the blade pen can be chamfered with a repetition of the curvature of the inner surface of the engine duct in the zone of the first stage of the low pressure valve with a decrease in the radius in the direction of flow of the working fluid with a clearance sufficient for unimpeded rotation of the impeller with blades.

The technical result of the invention, achieved by the above set of characteristics of the blades of the impeller of the first stage of the rotor of the low pressure turbojet engine, is to increase efficiency and expand the range of regimes of gas-dynamic stability of the compressor by 2.2% while increasing the resource of the blade by 2 times.

The invention is illustrated by drawings, where

in fig. 1 shows a blade of the impeller of the first stage, side view;

in fig. 2 - the blade of the impeller of the first stage, top view;

in fig. 3 - feather blades of the impeller of the first stage, a cross section;

in fig. 4 - a fragment of the disk of the impeller of the first stage, frontal projection.

A turbojet engine includes a housing with a flow part, limited along the peripheral contour of the engine housing. The rotor shaft of the low pressure rotor is made of a stepped drum-disk design, including no more than four disks with working blades.

The blade contains a feather 1 with a radial axis and a shank 2 with a longitudinal axis. The blade is designed to be installed in any of the grooves 3 of the disk 4 of the impeller of the first stage, for which the shank of the 2 blades has a longitudinal axis, coaxial or parallel to the geometric axis of the groove 3 of the disk 4 and forming with the axis of the rotor in the projection onto a conditional axial plane normal to the radial axis pen 1 blades, the angle of installation of the shank of the blade α ₀ defined in the range α ₀ = (17 ÷ 27) °.

The feather 1 of the blade is made with an axial twist variable relative to the rotor axis, increasing with radial distance from the axis of the rotor shaft with a pen twist gradient G _3p , defined in the range of the mentioned axial plane in the range

G _s.p. = (α _p -α _k ) / L _cp = (124.0 ÷ 186.8) [deg / m],

where α _to - the projection angle of the twist of the chord of the root section of the pen 1 of the blade relative to the axis of the rotor in the conditional axial plane of the rotor normal to the radial axis of the blade; α _p - a similar projection of the swirl angle relative to the rotor axis of the most remote peripheral chord of the pen in a plane parallel to the axial plane; L _cp - the average axial length of the feather blades.

The feather 1 of the blade is made with side edges 5 diverging to the peripheral end 6 with a gradient of increasing the chord G _yx ,

G _yx = (L _p.x -L _c.x ) / L _cp = (7.2 ÷ 10.7) · 10 ^-2 [m / m],

where L _p.x - the length of the peripheral chord connecting the edges 5 of the pen 1 of the scapula; L _K. — the length of the root chord connecting the edges 5 of the pen 1 of the blade in a conditional plane parallel to the axial plane of the rotor; L _cp - the average axial length of the pen 1 of the scapula.

The blade is equipped with an anti-vibration shelf 7 located in the area of one third of the length from the peripheral end 6 of the pen 1 of the blade and oriented along the flow of the working fluid. Each end 8 of the indicated shelf 7 is made with the possibility of mutual support on facing a similar end face of an adjacent blade of the impeller.

The feather 1 of the blade is convex-concave, with a concave surface in the form of a trough 9, endowed with a discharge function, and with a convex surface forming the backrest 10 of feather 1 with the function of diluting the pressure and suction of the flow of the working fluid during rotation of the impeller. The chord connecting the lateral edges 5 of the pen 1 in the root zone 11 forms, with the axis of the rotor in the projection onto the said conventional plane, the angle of installation of the pen 1, practically no less than the angle α _{to the} installation of the shank 2 of the blade.

Feather 1 of the blade is made variable in width and height of feather 1 with a thickness defined in cross section as the difference in height of the backrest 10 and trough 9 relative to the conditional chord 12 connecting the side edges 5 of the feather 1 of the blade.

The peripheral end face 6 of the pen 1 of the blade is made beveled with a repetition of the curvature of the inner surface of the engine duct in the area of the first stage of the low pressure valve with a decrease in the radius in the direction of flow of the working fluid with a clearance sufficient for unimpeded rotation of the impeller with blades. The blade of the impeller of the first stage of the rotor KND TRD is stage-by-stage made from a rod of an aircraft alloy. At the first stage, a fragment of the rod of the required length is cut, from which the blade blank with local thickenings in the areas of the shank 2 and the anti-vibration shelf 7 is executed by electric upsetting and subsequent machining. In the next step, the blank is subjected to general heating in an electric furnace to the state of thermoplasticity and hot forging is performed, using a stamp consisting of two reciprocal profiled half-matrices. The working surface of one of the die semi-matrices includes a section whose shape is made of the mating spatial surface of the back 10 of the pen 1 of the scapula. The working surface of the other die half-matrix includes a section whose shape is made of the mating spatial surface of the trough 9 of the pen 1 of the scapula. After that, the blade is subjected to mechanical processing, including grinding the flap milling, pulling the shank 2.

The refinement of the streamlined surfaces of the profiles of the pen 1 and the anti-vibration shelf 7 is performed by milling and subsequent polishing. The contact ends 8 of the anti-vibration shelf 7 are strengthened by applying a high-strength layer to them.

The blade made in this way consists of a single pen 1 with a shank 2 and an anti-vibration shelf 7, made as a segment of the assembled ring of the blade ring of the impeller of the first stage of the low-pressure turbine engine rotor.

The profile of the feather blade has the following geometric parameters:

- in the root section, the profile of the pen 1 of the scapula is made with a maximum profile thickness C _max = 5.59 mm; pen chord length - 61.5 mm; the angle α _{to the} installation of the profile of the pen 1 to the axis of rotation of the rotor in the projection onto the axial plane of the latter, normal to the axis of the pen blade, is 22 °;

- in the peripheral section, the profile of the blade feather is made with a maximum profile thickness C _max = 2.08 mm; feather chord length adopted 82 mm; the angle α _p setting the profile of the pen to the axis of rotation of the rotor in the projection onto the axial plane of the latter, normal to the axis of the pen blade, is 60 °;

- the average axial length L _{cp of the} profile of pen 1 is 245 mm.

The anti-vibration shelf 7 of the blade is made with a maximum thickness of 5 mm and is placed on the average radius from the axis of rotation of the rotor, adopted 388 mm, with contact surfaces made at an angle of 25 ° to the axis of rotation of the rotor in the projection on the axial plane of the latter, normal to the axis of the blade blade.

The blade is made for fixing on the disk of the impeller of the rotor shaft by installing the shank 2 in the groove 3 of the rim of the disk 4.

The work is as follows.

When the compressor is operating, each blade of the impeller of the first stage of the KND rotor interacts with the working fluid, transferring the kinetic and potential energy to the latter. The result is a flow of a compressible working fluid directed towards the exit from the impeller rim of the impeller, which flows from the interscapular channels of the impeller rim of the rotor impeller to the blades and into the interscapular channels of the stator guide apparatus of the first stage. After alignment in the guiding apparatus, the flow enters the subsequent stages of the low pressure switch.

In the process of implementing the design of the impeller blade of the first stage of the KND rotor developed in the invention, the technical result is achieved only when the blade is installed in the impeller with the profile of the pen 1 in the root section of the blade at an angle α _to the axis of the rotor in the projection onto the conditional axial plane of the rotor, normal to the radial axis of pen 1, in the range of angular values α _к = (17 ÷ 27) °. As the axis of the pen 1 of the blade, the only straight longitudinal axis of the pen profile is adopted, which coincides with the axis of twist of the profile. As the axis of the rotor adopted the axis of rotation of the rotor.

In combination with the simultaneous coordinated satisfaction of the matching conditions of the geometric and aerodynamic parameters of the spatial configuration of the pen and the gradients of their variation along the height of the scapula found in the invention. When assigning the angle α _to the root section of the blade, taken from the interval of values α _to = (17 ÷ 27) °, found in the invention, taking into account the installation angles of the pen profile of the subsequent stages of the compressor rotor, the highest values of efficiency, reserves of the compressor compressor and the resource of the blade .

With a decrease in the angle α _to <17 °, the range of gas-dynamic stability of the compressor operation is significantly limited, the efficiency of the stage decreases, and the risk of an accidentally dangerous stall of the air flow from the convex back of the 10 blades with the resulting loss of the GDU increases. With an increase in the angle α _to > 27 °, the risk of disruption of the air flow from the trough 9 of the feather 1 of the scapula increases and the efficiency decreases. In addition, with an increase in the angle α _to > 27 °, the voltage in the blade increases unjustifiably at all KND operation modes, which leads to a decrease in the resource, an increase in the material consumption of the blades, and ultimately to a heavier compressor and a decrease in the operational efficiency of the engine.

Similar processes take place with obtaining a positive result when observing and negative when going beyond the boundaries of the gradient ranges G _y.p found in the group of inventions along the length L _{cp of} pen 1 of the blade. When performing a three-dimensional profile of the feather of the blade with the gradient values G _y.p <124.0 [deg / m], the range of GDU operation of the _{LPC is} significantly limited, the efficiency of the stage decreases and the risk of an accidentally dangerous stall of the air flow from the convex back of the 10 blades with the resulting loss of GDU increases . An increase in the ratio of the difference in the angles of installation of the chord 12 of the pen 1 along the length of the blade to values of the gradient G _yx exceeding the upper limit G _yx adopted by the invention> 186.8 [deg / M], leads to an unacceptable decrease in the opening angle of the peripheral portion of the feather 1 of the blade, which in turn, it leads to a decrease in efficiency, a negative reduction in the range of the compressor GDU and an unacceptable mismatch between the operation of the first stage of the rotor and the subsequent stages of the low-pressure compressor. The gradient G _{y.x of the} increase in the chord 12 of the pen 1 of the scapula along the average length L _{cp of the} pen of the scapula 1 characterizes the windage of the pen 1, formed as a result of the angular divergence of the input and output side edges 5 of the pen 1 from the sleeve to the peripheral end 6.

Sailing pen 1 along the height of the scapula is profiled according to the mentioned gradient G _{yx of the} angular expansion of the chord 12 of the pen with the stated range G _yx = (7.2 ÷ 10.7) · 10 ^-2 [m / m], which provides a technical result of the invention. The decrease in the ratio of the difference between the lengths of the peripheral and root chords of the pen 1 to the average length L _{cp of the} pen (G _y.x <7.2 · 10 ^-2 ) leads to the formation of insufficient density of filling the peripheral annular portion of the cross-sectional area of the flow part of the shoulder blade with the peripheral portions of pen 1 blades in a projection onto a conventional plane normal to the axis of the rotor. As a result, an unacceptable decrease in the GDU stock occurs, a narrowing of the range of gas-dynamic stability of the compressor and a significant decrease in efficiency due to the possible disruption of the air flow from the back of the 10 blades. The increase (G _yx > 10.7 · 10 ^-2 ) leads to an unjustified increase in losses from friction of the flow on the profile of the pen 1 of the blade and to reduce the efficiency of the compressor.

An increase in the resource of the blade by two times is achieved if the condition of the ratio of the difference in thickness to the average length of the feather 1 of the blade, taken within the specified range of gradient values G _y.t = (1.25 ÷ 1.53) · 10 ^-2 [m / m] by providing the required static and dynamic stiffness with optimal material consumption of the profile of the pen 1 of the blade.

When the gradient values G _y.t <1.25 · 10 ^-2 [m / m], an excessive increase in material _consumption occurs due to the increase in the thickness of the peripheral part of the blade that is not justified by real load combinations, which leads to an overestimation of the compressor mass and a decrease in engine efficiency.

When the gradient values G _y.t > _1,53 · 10 ^-2 [m / m] the required increase in the resource of the blade is not achieved due to a decrease in dynamic strength during operation of the compressor due to an unjustified increase in the parameters of bending vibrations of the profile of pen 1 with an unacceptable decrease in the maximum thickness profile in the most loaded peripheral part of the length of the feather blade.

Thus, by improving the design and aerodynamic parameters of the blades of the impeller of the first stage, they increase the efficiency and expand the range of gas-dynamic stability modes of the engine’s low pressure without increasing the material consumption of the blades.

Claims (5)

1. The blade of the grooved disk of the impeller of the rotor of the compressor of low pressure (KND) turbojet engine (turbojet engine), including the flow part, limited along the peripheral contour of the engine housing, characterized in that it contains a feather with a radial axis and a shank with a longitudinal axis and is intended for installation in any of the grooves of the disk of the impeller of the first stage, for which the shank of the blade has a longitudinal axis, coaxial or parallel to the geometric axis of the groove of the disk and forming with the axis of the rotor in the projection on the conditional axial plane normal to the radial axis of the blade feather, blade angle α ₀ , defined in the range α ₀ = (17 ÷ 27) °; in addition, the blade feather is made with a variable axial twist relative to the axis of the rotor, increasing with radial distance from the axis of the rotor shaft with a pen twist gradient G _zp defined in the projection onto said conditional axial plane in the range
G _s.p. = (α _p -α _k ) / L _cp = (124.0 ÷ 186.8) [deg / m],
where α _to is the projection of the angle of twist of the chord of the root section of the feather of the blade relative to the axis of the rotor in the conditional axial plane of the rotor normal to the radial axis of the blade; α _p - a similar projection of the swirl angle relative to the rotor axis of the most remote peripheral chord of the pen in a plane parallel to the axial plane; L _cp is the average axial length of the blade feather; moreover, the blade feather is made with lateral edges diverging to the peripheral end with a gradient of increasing chords G _yx ,
G _yx = (L _p.x -L _c.x ) / L _cp = (7.2 ÷ 10.7) · 10 ^-2 [m / m],
where L _p.x - the length of the peripheral chord connecting the edges of the feather blades; L _K..x is the length of the root chord connecting the edges of the feather blade in a conventional plane parallel to the axial plane of the rotor; L _cp - the average axial length of the feather blades. 2. The blade according to claim 1, characterized in that the blade is equipped with an anti-vibration shelf located in the area of one third of the length from the peripheral end of the feather of the blade and oriented along the flow of the working fluid, and each end of the specified shelf is made with the possibility of mutual support on its similar the end face of the adjacent impeller blades. 3. The blade according to claim 1, characterized in that the feather of the blade is convex-concave, with a concave surface in the form of a trough endowed with a discharge function, and with a convex surface forming the back of the pen with the function of diluting the pressure and suction of the flow of the working fluid during rotation of the working fluid wheel furthermore chord joining the side edges of the pen in the root zone, forms with the rotor axis in the projection onto said notional plane angle of the stylus, substantially at least _{to the} setting angle α of the blade root. 4. The blade according to claim 1, characterized in that the feather of the blade is made variable in width and height of the feather with a thickness defined in cross section as the difference in height of the back and trough relative to the conditional chord connecting the lateral edges of the blade feather. 5. The blade according to claim 1, characterized in that the peripheral end face of the blade pen is beveled with a repetition of the curvature of the inner surface of the engine duct in the area of the first stage of the low pressure valve with a decrease in radius in the direction of flow of the working fluid with a clearance sufficient for unimpeded rotation of the impeller with blades .

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