A design method for an inducer wheel of a liquid rocket engine turbopump and the inducer wheel itself.

Abstract

This invention discloses a design method and inducer for a liquid rocket engine turbopump. Based on the overall design requirements of the liquid rocket engine, the operating conditions of the inducer are determined. According to the design requirements and empirical formulas, the basic parameters of the inducer are initially determined. Based on the range of core parameters, different combinations of core parameters are used to establish multiple initial three-dimensional models of the inducer. Simulations are performed on each of the established initial three-dimensional models to obtain the cavitation performance of the inducer. Based on the flow analysis results, the inducer with the optimal blade profile among all parameter combinations is obtained. The selected inducer with the optimal blade profile is then optimized and adjusted until the liquid rocket engine turbopump inducer with the best cavitation performance is obtained. This invention can design a liquid rocket engine turbopump inducer with good cavitation performance.

Description

Technical Field

[0001] This invention relates to the field of rocket engines, and in particular to a design method for an inducer wheel of a liquid rocket engine turbopump and the inducer wheel itself. Background Technology

[0002] The inducer wheel of a liquid rocket engine turbopump is a crucial component of the turbopump assembly. Its primary function is to enhance the turbopump's ability to draw in propellant. During operation, the propellant needs to be delivered to the combustion chamber under high pressure and high speed. The inducer wheel increases the propellant pressure by creating a pre-pressurization effect at the pump inlet, thereby preventing cavitation during propellant intake.

[0003] In daily practice, the existing technical solutions have been found to have the following problems:

[0004] Currently, the cavitation specific speed of the inducer wheel of the existing liquid rocket engine turbopump in China is generally at the level of 3000-4500 rpm, with the better ones around 4500 rpm. It is difficult to break through 4800 rpm. This causes the speed of the turbopump to be affected by pump cavitation and cannot be improved, thus limiting the performance of the pump and turbine and making it impossible to achieve lightweight and high performance.

[0005] In view of this, it is necessary to provide a new technical solution to solve the above problems. Summary of the Invention

[0006] To address the aforementioned technical problems, this application provides a design method and inducer for a liquid rocket engine turbopump, which can design an inducer for a liquid rocket engine turbopump with good cavitation performance.

[0007] A design method for an inducer in a turbopump for a liquid rocket engine, comprising:

[0008] Based on the overall design requirements of the liquid rocket engine, determine the operating conditions of the inducer.

[0009] Based on design requirements and empirical formulas, the basic parameters of the inducer are preliminarily determined;

[0010] Based on the range of core parameters of the inducer, different core parameters are combined to establish multiple initial three-dimensional models of the inducer;

[0011] By selecting a suitable flow analysis model, using computational fluid dynamics software, and setting initial and boundary conditions, simulations were performed on multiple initial three-dimensional models of the induced wheel to obtain the cavitation performance of the induced wheel.

[0012] Based on the flow analysis results, the inducer with the optimal blade profile among all parameter combinations was obtained;

[0013] The selected inducer with the optimal blade profile was optimized and adjusted to obtain the liquid rocket engine turbopump inducer with the best cavitation performance.

[0014] Preferably, in the preliminary determination of the parameters of the inducer based on design requirements and empirical formulas, the basic parameters of the inducer include the flow coefficient, pitch, diameter, number of blades, blade density, inlet hub ratio, outlet hub ratio, inlet wrap angle, minimum thickness of the blade leading edge, blade wedge angle, blade leading edge placement angle on the outer flow line, blade outlet angle on the outer flow line, and the structure and size of the hub.

[0015] Preferably, the method for establishing the three-dimensional model of the inducer blades in the step of combining different core parameters according to the core parameter range of the inducer to establish multiple initial three-dimensional models of the inducer includes:

[0016] Design the pressure surface curve and suction surface curve of the flat plate blade according to the relationship curve between the inducer blade wrap angle and the pitch;

[0017] Based on the blade thickness at the rim, the blade angle to the axial direction, and the blade wedge angle, the pressure surface curve and suction surface curve of the flat blade are structurally adjusted. According to the pitch variation rule, a smooth pressure surface curve and suction surface curve are obtained in the radial range from the rim to the hub.

[0018] The generated pressure surface curves and suction surface curves are respectively combined into smooth planes to construct the pressure surface and suction surface of the inducer blade;

[0019] A three-dimensional model of the inducer blade is established based on the constructed pressure and suction surfaces of the inducer blade.

[0020] Preferably, the flow coefficient is selected in the range of 0.06-0.09.

[0021] Preferably, the minimum thickness of the blade leading edge is 0.2-0.35 mm; the blade wedge angle is 4-6°; the blade angle with the axial direction is 65-100°; the blade leading edge placement angle on the outflow line is 6°-9°; and the blade exit angle on the outflow line is 12°-15°.

[0022] Preferably, the inlet wrap angle ranges from 0 to 130°; the blade inlet pitch and the blade outlet pitch are both constant values; and the pitch between the blade inlet and the blade outlet transitions smoothly within the total wrap angle range.

[0023] Preferably, the inlet hub ratio is selected in the range of 0.2-0.4; the outlet hub ratio is selected in the range of 0.5-0.75.

[0024] Preferably, the cascade density ranges from 1.8 to 2.4.

[0025] According to another aspect of this application, a liquid rocket engine turbopump inducer is also provided, designed using the liquid rocket engine turbopump inducer design method, comprising: a hub and blades; the front diameter of the hub is smaller than the rear diameter, and the hub cross-section is parabolic; the leading edge profile of the blades is a swept blade; the number of blades is three, and the blades are arranged around the outer surface of the hub; the outlet angle of the liquid rocket engine turbopump inducer is smaller than the inlet flow angle of the downstream centrifugal impeller.

[0026] Compared with the prior art, this application has at least the following beneficial effects:

[0027] 1. This invention can design a liquid rocket engine turbopump inducer with good cavitation performance, which can effectively avoid the problem of poor performance consistency in batch delivery, and has a short design time and high design efficiency.

[0028] 2. In the process of modeling the inducer blade, this invention constructs two curved surfaces by generating a smooth curve of pitch variation law in the radial range from the rim to the hub, based on the pitch variation rule. The curved surfaces generated by this method are simple, easy to process, easy to ensure accuracy, convenient to detect, and have good consistency in cavitation performance. Attached Figure Description

[0029] The following sections will describe some specific embodiments of the invention in a detailed manner by way of example and not limitation, with reference to the accompanying drawings. The same reference numerals in the drawings denote the same or similar parts or portions. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings:

[0030] Figure 1 This is a schematic diagram of the overall process of the liquid rocket engine turbopump inducer design method of the present invention;

[0031] Figure 2 A cross-sectional view of the inducer wheel of a liquid rocket engine turbopump;

[0032] Figure 3 A side view of the inlet end of the turbopump of a liquid rocket engine;

[0033] Figure 4 A diagram showing the cylindrical surface development of the inducer blade of a liquid rocket engine turbopump.

[0034] Figure 5 A graph showing the relationship between the wrap angle and pitch of the inducer blades in a liquid rocket engine turbopump.

[0035] Figure 6 A graph showing the variation of the inducer wrap angle and pitch of a liquid rocket engine turbopump.

[0036] Figure 7 Modeling curves for the inducer blades;

[0037] Figure 8 Model the surface diagram of the inducer blade;

[0038] Figure 9 This is a schematic diagram of the vertical blades of the inducer.

[0039] Figure 10 This is a schematic diagram of the forward tilting blades of the inducer.

[0040] Figure 11 This is a schematic diagram of the backward tilting blades of the inducer. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0042] like Figure 1 As shown, a design method for an inducer in a liquid rocket engine turbopump includes:

[0043] S1. Determine the working conditions of the inducer wheel based on the overall design requirements of the liquid rocket engine.

[0044] Specifically, the operating conditions of the inducer include: propellant type and properties, design flow rate, target pressure rise, and operating speed.

[0045] The design flow rate is determined by the engine thrust, the target pressure rise must meet the minimum pressure requirements at the main impeller inlet, and the operating speed is determined by the turbine power matching.

[0046] S2. Based on design requirements and empirical formulas, the basic parameters of the inducer are initially determined.

[0047] Specifically, the basic parameters of the inducer include flow coefficient, pitch, diameter, number of blades, blade density, inlet hub ratio, outlet hub ratio, inlet wrap angle, minimum blade leading edge thickness, blade wedge angle, blade leading edge placement angle on the outer flow line, blade outlet angle on the outer flow line, and the structure and size of the hub.

[0048] S3. Based on the range of core parameters of the inducer, combine different core parameters to establish multiple initial three-dimensional models of the inducer.

[0049] Specifically, the methods for establishing the three-dimensional model of the inducer blade include:

[0050] Based on the relationship curve between the inducer blade wrap angle and the pitch, the pressure surface curve and suction surface curve of the flat blade were designed respectively.

[0051] Based on the blade thickness at the rim, the blade angle to the axial direction, and the blade wedge angle, the pressure surface curve and suction surface curve of the flat blade are structurally adjusted. According to the pitch variation rules, smooth pressure surface curves and suction surface curves are obtained within the radial range from the rim to the hub. Figure 7 As shown.

[0052] The generated pressure surface curves and suction surface curves are respectively combined into smooth planes to construct the pressure surface and suction surface of the inducer blade, as shown below. Figure 8 As shown.

[0053] A three-dimensional model of the inducer blade is established based on the constructed pressure and suction surfaces of the inducer blade.

[0054] like Figure 2-4 As shown, when establishing multiple initial 3D models of the inducer, the specific range of the core parameters of the inducer is as follows:

[0055] The flow coefficient φ is selected within the range of 0.06-0.09. The selection of the inducer flow coefficient has a significant impact on its cavitation specific speed. An excessively large flow coefficient leads to large variations in the inlet velocity, resulting in poor cavitation performance. An excessively small flow coefficient leads to unstable inlet flow, large backflow, and deterioration of cavitation performance.

[0056] To balance manufacturing precision and product performance consistency, the leading edge thickness should be as thin as possible. The minimum required blade thickness is determined by blade stress and natural frequency. In this embodiment, the minimum leading edge thickness e is... 1e The range is 0.2-0.35mm.

[0057] The blade wedge angle ranges from 4 to 6°; the blade angle to the axial direction ranges from 65 to 100°; the blade leading edge placement angle β1 on the outer flow line ranges from 6° to 9°; and the blade exit angle β2 on the outer flow line ranges from 12° to 15°. The selection of the blade exit angle on the outer flow line depends on the inlet diameter of the inducer and the centrifugal impeller.

[0058] A thinner inducer inlet leading edge provides less impact on the incoming flow, resulting in a higher cavitation specific speed. However, even a slight misdesign of the inlet placement angle can rapidly degrade cavitation performance. In this embodiment, the inlet wrap angle ε... sb The range is 0-130°, and both the blade inlet and outlet pitches are constant. This stable inducer outlet flow angle allows the propellant to enter the centrifugal impeller inlet with minimal resistance. Furthermore, the pitch between the blade inlet and outlet transitions smoothly within the total wrap angle range, ensuring a stable flow field distribution within the inducer. Figure 5 As shown.

[0059] The hub shape is parabolic. Due to centrifugal force, the parabolic hub helps establish a uniform pressure gradient in the inducer. Simultaneously, as the outlet hub ratio increases, the tendency for flow separation decreases. Fluid acceleration from the inducer outlet to the centrifugal impeller inlet leads to a corresponding decrease in static pressure, thereby increasing the tendency for cavitation. In this embodiment, the outlet hub ratio r... h2 / r t2 The selection range is 0.5-0.75. The specific value should take into account whether the inducer passes through the pump shaft, and the inducer performs best within this range.

[0060] The hub ratio of the inlet idler wheel without axle is r. h1 / r t1 The selection range is 0.2-0.4. Although an excessively low inlet hub ratio will increase the inlet flow area and improve cavitation resistance, it will also increase the deformation of the blade leading edge and increase the blade stress, which will reduce the reliability of the turbopump.

[0061] The blade cascade density ranges from 1.8 to 2.4. If the blade cascade density is too low, it will affect the pressure rise in the inducer because the deflection angle changes significantly. Figure 6 The curve showing a large change in slope between the wrap angle and axial position reduces the cavitation performance and efficiency of the inducer, and increases the tendency for pressure pulsation under partial load. Blades with L / t > 2.5 offer little advantage in cavitation performance. Ultra-long blades have little impact on the head generated by the inducer, but reduce bubble formation in long channels.

[0062] Furthermore, reducing the number of blades z increases the blade pitch t, ​​increases the area and diameter a1 of the throat region, and reduces fluid flow blockage, all of which improve the cavitation specific speed of the inducer. Therefore, inducers are typically selected with 2-4 blades.

[0063] Inducers are typically installed upstream of the impeller in a centrifugal pump or used independently as a pre-pressure pump. However, combining a centrifugal impeller with moderate suction capacity with an inducer that offers high cavitation resistance does not guarantee high cavitation resistance in a turbopump. In particular, if cavitation occurs on the blade pressure surface, the maximum flow rate may be limited by the downstream centrifugal impeller's flow angle. To improve the cavitation performance of a turbopump, the inducer outlet angle β2 should be smaller than the downstream centrifugal impeller's inlet flow angle. Therefore, the downstream centrifugal impeller's inlet flow angle should be greater than 16°.

[0064] It should be noted that unreasonable design parameters lead to partial propellant backflow near the design point. At low flow rates, this backflow becomes very strong, causing intense vortices at the inducer inlet and centrifugal impeller inlet. Due to rotation, the static pressure forms a parabolic distribution at the inducer inlet. Under low suction pressure, steam-filled vortices are generated near the inducer leading edge. These vortices cause severe pulsation. By selecting appropriate blade density, a smoothly transitioning variable-pitch inducer, blade leading-edge sweep, and a parabolic hub for the inducer within reasonable ranges, this pulsation can be largely avoided, improving the cavitation performance of the turbopump and the inducer efficiency.

[0065] Furthermore, to address the challenges of machining blade profiles, ensuring machining accuracy, and preventing deformation during high-speed operation, the following solutions are provided: Figure 3 One option is to use flat blades for the inducer. Flat blades are easy to manufacture and their precision can be guaranteed. For example... Figure 9-10 As shown, the blades can be vertical, forward-curved, or backward-curved. The optimal range for the blade wedge angle α1 is 4-6°, and the angle α2 between the blade and the axial direction is selected within the range of 65-100°. The specific scheme adopted depends on the results of fluid-structure interaction numerical simulation under the design conditions, selecting the scheme with the smallest axial deformation of the blade.

[0066] S4. Select a suitable flow analysis model, use computational fluid dynamics software, and set initial and boundary conditions to simulate the initial three-dimensional models of multiple inducer wheels to obtain the cavitation performance of the inducer wheels.

[0067] A suitable flow model, such as a theoretical model of an axial flow pump or a three-dimensional viscous fluid dynamics model, is selected to analyze the flow inside the inducer. Computational fluid dynamics (CFD) software is used to set boundary and initial conditions, and numerical simulations are performed on the established three-dimensional inducer model.

[0068] S5. Based on the flow analysis results, obtain the inducer with the optimal blade profile among all parameter combinations.

[0069] The blade profile of the inducer is the core of its hydrodynamic design, directly affecting cavitation performance, energy conversion efficiency, and structural strength. Key parameters of the inducer blade profile include leading edge shape, trailing edge shape, thickness distribution, and camber distribution. Based on the flow analysis results, the inducer with the optimal blade profile under these conditions is obtained.

[0070] S6. Optimize and adjust the parameters of the selected inducer with the optimal blade profile until the liquid rocket engine turbopump inducer with the best cavitation performance is obtained.

[0071] A prototype of the inducer was manufactured and tested. Through these tests, parameters such as the flow rate, head, efficiency, and cavitation performance of the turbopump were measured and compared with the design values. The selected inducer with the optimal blade profile was then optimized and adjusted until the liquid rocket engine turbopump inducer with the best cavitation performance was obtained.

[0072] When optimizing and adjusting the parameters of the inducer, the performance of the inducer can be optimized to meet the design requirements by adjusting design parameters such as the number of blades, blade density, and pitch.

[0073] Based on the same inventive concept, according to another aspect of this application, a liquid rocket engine turbopump inducer is also provided, designed using the liquid rocket engine turbopump inducer design method, comprising: a hub and blades; the front diameter of the hub is smaller than the rear diameter, and the hub cross-section is parabolic; the leading edge profile of the blades is a swept blade; the number of blades is 3, and the blades are arranged around the outer surface of the hub; the outlet angle of the liquid rocket engine turbopump inducer is smaller than the inlet flow angle of the downstream centrifugal impeller.

[0074] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0075] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0076] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.

[0077] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A design method for an inducer in a liquid rocket engine turbopump, characterized in that, include: Based on the overall design requirements of the liquid rocket engine, determine the operating conditions of the inducer. Based on design requirements and empirical formulas, the basic parameters of the inducer are preliminarily determined; Based on the range of core parameters of the inducer, different core parameters are combined to establish multiple initial three-dimensional models of the inducer; By selecting a suitable flow analysis model, using computational fluid dynamics software, and setting initial and boundary conditions, simulations were performed on multiple initial three-dimensional models of the induced wheel to obtain the cavitation performance of the induced wheel. Based on the flow analysis results, the inducer with the optimal blade profile among all parameter combinations was obtained; The parameters of the selected inducer with the optimal blade profile are optimized and adjusted until the liquid rocket engine turbopump inducer with the best cavitation performance is obtained. The method for establishing the three-dimensional model of the inducer blades, which involves combining different core parameters according to the range of core parameters of the inducer to establish multiple initial three-dimensional models of the inducer, includes: Design the pressure surface curve and suction surface curve of the flat plate blade according to the relationship curve between the inducer blade wrap angle and the pitch; Based on the blade thickness at the rim, the blade angle to the axial direction, and the blade wedge angle, the pressure surface curve and suction surface curve of the flat blade are structurally adjusted. According to the pitch variation rule, a smooth pressure surface curve and suction surface curve are obtained in the radial range from the rim to the hub. The generated pressure surface curves and suction surface curves are respectively combined into smooth planes to construct the pressure surface and suction surface of the inducer blade; A three-dimensional model of the inducer blade is established based on the constructed pressure and suction surfaces of the inducer blade.

2. The liquid rocket engine turbopump inducer design method as described in claim 1, characterized in that, Based on design requirements and empirical formulas, the basic parameters of the inducer are initially determined. These parameters include flow coefficient, pitch, diameter, number of blades, blade density, inlet hub ratio, outlet hub ratio, inlet wrap angle, minimum blade leading edge thickness, blade wedge angle, blade leading edge placement angle on the outer flow line, blade outlet angle on the outer flow line, and the structure and dimensions of the hub.

3. The liquid rocket engine turbopump inducer design method as described in claim 2, characterized in that, The flow coefficient is selected in the range of 0.06-0.

09.

4. The liquid rocket engine turbopump inducer design method as described in claim 2, characterized in that, The minimum thickness of the blade leading edge ranges from 0.2 to 0.35 mm; the blade wedge angle ranges from 4 to 6°; the blade angle with the axial direction ranges from 65 to 100°; the blade leading edge placement angle on the outflow line ranges from 6° to 9°; and the blade exit angle on the outflow line ranges from 12° to 15°.

5. The liquid rocket engine turbopump inducer design method as described in claim 2, characterized in that, The inlet wrap angle ranges from 0 to 130°; both the blade inlet pitch and the blade outlet pitch are constant values. The pitch between the blade inlet and the blade outlet transitions smoothly within the total wrap angle range.

6. The liquid rocket engine turbopump inducer design method as described in claim 2, characterized in that, The inlet hub ratio should be selected within the range of 0.2-0.4; The range for the wheel hub ratio in export applications is 0.5-0.

75.

7. The liquid rocket engine turbopump inducer design method as described in claim 2, characterized in that, The density of the cascade is in the range of 1.8-2.

4.

8. An inducer for a liquid rocket engine turbopump, characterized in that, Designed using the liquid rocket engine turbopump inducer design method according to any one of claims 1-7, it includes: a hub and blades; the front diameter of the hub is smaller than the rear diameter, and the hub cross-section is parabolic; the leading edge profile of the blades is a swept blade; the number of blades is 3, and the blades are arranged around the outer surface of the hub; the outlet angle of the liquid rocket engine turbopump inducer is smaller than the inlet flow angle of the downstream centrifugal impeller.

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