Active control method of air cavitation for fuel pump

Abstract

The application discloses a kind of fuel pump air type cavitation active control method, belong to fuel pump technical field, solve the problem that when fuel pump transports gas type fuel under high-altitude environment, air type cavitation phenomenon is prone to occur and causes flow pressure to drop suddenly.The application is designed when fuel pump impeller, volute and other three-dimensional models, using the method of increasing flow design, exhaust passage is set on volute oil outlet pipeline, air type cavitation bubble generated in impeller and volute is carried away by actively sacrificing part of medium energy, thereby improving the problem that pressure drops suddenly due to air type cavitation phenomenon caused by fuel pump.And in order to avoid the diameter of exhaust passage being too large and causing large pressure loss, the application gradually increases the exhaust pipe and rated flow to ensure gas discharge while meeting the demand of aviation fuel, maximizes the reduction of pressure loss.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel pumps, and in particular to a method for actively controlling air-type cavitation in a fuel pump. Background Art

[0002] Fuel pumps are widely used in aircraft fuel systems, and their cavitation performance in high-altitude environments is crucial to the reliability and stability of platform operations. At normal temperature and pressure, the gas content of RP-3 jet fuel is 6% to 14%. Due to the unique characteristics of the pumping medium, air bubbles form during fuel pump operation at high altitudes, a phenomenon known as air-type cavitation. In air-type cavitation, the development, transformation, and movement of air bubbles within the fuel pump impeller channel lead to dynamic phenomena such as separation of air from the jet fuel, bubble fragmentation, and coalescence. When bubbles accumulate to a certain level in flow-through components such as the suction chamber and impeller, forming air masses or pockets, they significantly impact the pump's head, flow rate, and efficiency, resulting in reduced pump performance.

[0003] Existing methods for controlling the occurrence and development of cavitation often include active and passive methods. The active method often uses blade slits. For example, the patent with application number 201910919236.8 discloses a method for improving the anti-cavitation performance of the impeller. An inducer is installed in front of the first-stage impeller of the pump, and an Archimedean spiral is used to fix long blades with gaps around the impeller. A gradually increasing gap of 1mm~2mm is opened at a distance from the head of the long blade. The angle between the direction of the gap and the flow direction is an acute angle. Although the anti-cavitation ability is improved, an inducer needs to be installed additionally, and the structure is complicated. The passive method is to modify the impeller inlet parameters, but since efficiency and cavitation cannot be achieved at the same time, in general, although the anti-cavitation performance can be improved by changing the blade inlet parameters, higher efficiency will be sacrificed. Summary of the Invention

[0004] In response to the above-mentioned problems in the prior art, the present invention provides a method for actively controlling air-type cavitation in a fuel pump, which solves the problem of sudden drop in flow rate and pressure caused by air-type cavitation when the fuel pump transports gas-containing fuel in a high-altitude environment.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A method for actively controlling air-type cavitation in a fuel pump is provided, comprising the steps of:

[0007] S1. Determine the fuel pump performance parameters based on the aircraft's altitude and fuel requirements. The performance parameters include rated flow. , rated boost , speed and cavitation margin ;

[0008] S2. Calculate the hydraulic parameters of the impeller and volute in the fuel pump based on the performance parameters of the fuel pump;

[0009] S3. Establish a three-dimensional model of the connection between the impeller and the volute based on the hydraulic parameters of the impeller and the volute, and model an exhaust pipe for communicating with the fuel tank on the volute oil outlet pipe of the three-dimensional model;

[0010] S4. Perform numerical simulation on the three-dimensional model and continuously increase the diameter of the exhaust pipe within the set threshold range of the exhaust pipe diameter to obtain the boost value at the rated flow rate for different exhaust pipe diameters. ;

[0011] S5. Determine whether there is a boost value Greater than or equal to rated boost pressure If yes, then go to step S6, otherwise increase the rated flow in the performance parameters of the fuel pump And return to step S2;

[0012] S6. Acquisition and boosting value The corresponding exhaust pipe diameter is determined, and the fuel pump is processed according to the minimum diameter of the exhaust pipe and the parameters of the three-dimensional model.

[0013] This solution works by employing a flow-enhancing design approach during the three-dimensional design of the fuel pump impeller, volute, and other components. This approach incorporates an exhaust channel within the volute outlet line. This channel sacrifices some of the medium's energy to remove air bubbles generated within the impeller and volute, thereby mitigating the pressure drop associated with air cavitation in the fuel pump. To avoid significant pressure loss caused by excessively large exhaust channel diameters, this solution minimizes pressure loss by gradually increasing the exhaust channel diameter and rated flow rate to ensure gas discharge while meeting aviation fuel requirements.

[0014] Furthermore, the exhaust duct in the 3D model is vertically connected to the volute oil outlet line. This vertical arrangement of the exhaust duct helps improve exhaust efficiency, ensuring that gas within the fuel pump system is effectively discharged, and further suppressing cavitation.

[0015] Furthermore, the threshold value of the exhaust pipe diameter is set The range is: when the rated flow hour, ; When rated flow hour, .

[0016] Furthermore, the method for numerical simulation of the three-dimensional model is:

[0017] S4.1. Perform preliminary meshing of the 3D model using CFD software;

[0018] S4.2, set a turbulence model in the flow channel in the three-dimensional model;

[0019] S4.2, set the boundary conditions of the three-dimensional model, and solve the single-phase flow by using JET A Liquid to obtain the test boost value of the three-dimensional model;

[0020] S4.3, increase the grid density of the three-dimensional model and obtain the test boost value of the three-dimensional model again;

[0021] S4.4, compare whether the change of the two test boost values is less than 5%, if yes, go to step S4.5, otherwise return to step S4.2. Step S4.4 is used to check the grid quality independence, so that the simulation result no longer depends on the refinement degree of the grid, and the reliability of the simulation result is ensured.

[0022] S4.5, simulate multiple outlet flow conditions by the three-dimensional model through the CFD software and obtain the boost value corresponding to the flow condition, and draw a flow boost curve;

[0023] S4.6, obtain the boost value under the rated flow through the flow boost curve.

[0024] Further, the turbulence model is RNG k-ε turbulence model or SST k-ω turbulence model. Both the RNG k-ε model and the SST k-ω turbulence model are based on the RANS equation, both of which are suitable for steady flow simulation and are specially used for steady flow problems. By solving the transport equations of turbulent kinetic energy k and dissipation rate ε, the turbulent viscosity coefficient for steady flow is provided, and then the influence of turbulence on steady flow is simulated. The SST k-ω turbulence model has better simulation effect on near-wall region and complex flow.

[0025] Further, the setting of the boundary conditions includes setting the boundary condition of the volute inlet as a pressure inlet, taking the total pressure of the known fluid entering the volute as an input parameter, and through the specified inlet pressure, the solver can calculate the flow characteristics entering the system according to the fluid dynamics equation. The boundary condition of the volute outlet is mass flow, and through the specified mass flow, the solver can calculate the appropriate flow velocity and pressure according to the internal flow field conditions. The boundary condition of the exhaust pipe outlet is a pressure outlet, and the pressure of the exhaust pipe is set to be equal to the pressure of the volute inlet to ensure the physical consistency of the system. The solid wall of the volute adopts a no-slip wall, and the no-slip wall condition makes the velocity of the fluid on the wall the same as the wall velocity, which can effectively simulate the interaction between the fluid and the solid surface and capture the formation and development of the boundary layer. The near-wall region adopts a stretching wall function method, which is an approximate method for processing turbulent flow near the wall. It describes the velocity distribution near the wall through an empirical formula or function, thereby avoiding the use of too fine grids near the wall. It can be automatically adjusted according to the density of the grid to ensure the stability and accuracy of the calculation results. The impeller and the volute dynamic static interface adopts the frozen rotor method. The frozen rotor method is a simplified method for processing the interface between the dynamic and static parts in a rotating machine. By assuming that the relative position between the impeller and the volute is fixed during the calculation process, the dynamic problem is approximated as a steady-state problem for processing. This method greatly simplifies the calculation, and when the speed is relatively stable, it can provide more accurate results.

[0026] Further, the convergence accuracy of the JET A Liquid solver residual error is 10 -5 . High-precision convergence requirements ensure the stability and reliability of the numerical simulation results, reducing errors and uncertainties.

[0027] Further, the flow size of the plurality of outlet flow conditions includes at least 0 times, 0.2 times, 0.4 times, 0.6 times, 0.8 times, 1.0 times and 1.2 times the rated flow. By simulating multiple flow conditions, it is ensured that the design can maintain good performance under different working conditions, improving the robustness and adaptability of the design.

[0028] Further, the hydraulic parameters of the impeller include the impeller inlet diameter, the impeller outlet diameter, the impeller outlet width, the number of blades, the blade wrap angle, the blade inlet installation angle and the blade inlet installation angle. The above-mentioned hydraulic parameter setting ensures the refinement and optimization of the impeller design, and improves the overall performance and efficiency of the fuel pump.

[0029] The application discloses an air type cavitation active control method for a fuel pump, which has the following beneficial effects:

[0030] The present application adopts the method of increasing flow when designing the three-dimensional model of the fuel pump impeller and volute, sets the exhaust passage on the volute oil outlet pipeline, and carries away the air-type cavitation generated in the impeller and volute by actively sacrificing part of the medium energy, thereby improving the problem of pressure drop caused by the air-type cavitation phenomenon of the fuel pump. In order to avoid the problem of too large diameter of the exhaust passage causing large pressure loss, the present application gradually increases the exhaust pipe and the rated flow to ensure the gas exhaust while meeting the demand of aviation fuel, and maximally reduces the pressure loss. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 The structure diagram of the active control method for the air-type cavitation of the fuel pump;

[0032] Figure 2 The structure diagram of the fuel pump;

[0033] Figure 3 The flow boost curve diagram. DETAILED DESCRIPTION

[0034] The specific embodiments of the present application are described below to facilitate the understanding of the present application by those skilled in the art, but it should be clear that the present application is not limited to the scope of the specific embodiments, and for those skilled in the art, it is obvious that various changes are within the spirit and scope of the present application defined and determined by the appended claims, and all the inventions utilizing the concept of the present application are within the scope of protection.

[0035] Example 1

[0036] Reference Figure 1 The present embodiment provides an active control method for the air-type cavitation of a fuel pump, comprising the steps of:

[0037] S1, determining the performance parameters of the fuel pump according to the altitude of the aircraft and the fuel demand, the performance parameters including the rated flow , the rated boost , the rotation speed and the cavitation allowance .

[0038] S2, calculating the hydraulic parameters of the impeller and the volute in the fuel pump according to the performance parameters of the fuel pump. The hydraulic parameters of the impeller include the impeller inlet diameter, the impeller outlet diameter, the impeller outlet width, the number of blades, the blade wrap angle, the blade inlet setting angle and the blade inlet setting angle. The above-mentioned hydraulic parameters are set to ensure the refinement and optimization of the impeller design, and to improve the overall performance and efficiency of the fuel pump.

[0039] S3, a three-dimensional model of the impeller and volute connection is established by the hydraulic parameters of the impeller and volute, and a exhaust pipe for communication with the fuel tank is modeled on the volute oil outlet pipeline of the three-dimensional model. The exhaust pipe in the three-dimensional model is vertically communicated with the volute oil outlet pipeline. The vertical arrangement of the exhaust pipe helps to improve the exhaust efficiency, ensure the effective exhaust of gas in the fuel pump system, and further inhibit cavitation.

[0040] S4, numerical simulation is carried out on the three-dimensional model, and the diameter of the exhaust pipe is increased in the set threshold range of the diameter of the exhaust pipe, and the supercharging value under the rated flow of different exhaust pipe diameters is obtained The set threshold of the diameter of the exhaust pipe is: when the rated flow , ; when the rated flow , .

[0041] S5, judge whether the supercharging value Is greater than or equal to the rated supercharging , if yes, go to step S6, otherwise increase the rated flow In the performance parameters of the fuel pump and return to step S2.

[0042] S6, get the exhaust pipe diameter corresponding to the supercharging value , and process the fuel pump according to the minimum diameter of the exhaust pipe and the parameters of the three-dimensional model.

[0043] In this embodiment, when designing the three-dimensional model of the fuel pump impeller, volute and the like, the flow rate design method is adopted, the exhaust passage is arranged on the volute oil outlet pipeline, and part of the medium energy is actively sacrificed to carry away the air type cavitation generated in the impeller and volute, thereby improving the problem of pressure drop caused by air type cavitation in the fuel pump. In order to avoid that the diameter of the exhaust passage is too large to cause large pressure loss, the present scheme gradually increases the exhaust pipe and the rated flow to ensure the exhaust of gas while meeting the demand of aviation fuel, and maximizes the reduction of pressure loss.

[0044] As a further scheme of the present embodiment, the method for numerical simulation of the three-dimensional model is:

[0045] S4.1, the three-dimensional model is preliminarily meshed by CFD software.

[0046] S4.2, set a turbulence model in the flow channel in the three-dimensional model. In this embodiment, the turbulence model is an RNG k-ε turbulence model or an SST k-ω turbulence model. Both the RNG k-ε model and the SST k-ω turbulence model are based on RANS equations, both of which are suitable for steady flow simulation and are specifically used for steady flow problems. By solving the transport equations of turbulent kinetic energy k and dissipation rate ε, the turbulent viscosity coefficient is provided for steady flow, and the influence of turbulence on steady flow is simulated. The SST k-ω turbulence model has better simulation effect on near-wall regions and complex flows.

[0047] S4.2, set the boundary conditions of the three-dimensional model, and solve the single-phase flow by using JET A Liquid to obtain the test boost value of the three-dimensional model. The convergence accuracy of the residual error of JET A Liquid is 10 -5 . The high-precision convergence requirement ensures the stability and reliability of the numerical simulation results, and reduces errors and uncertainties.

[0048] S4.3, increase the grid density of the three-dimensional model and obtain the test boost value of the three-dimensional model again.

[0049] S4.4, compare whether the change of the two test boost values is less than 5%, if yes, go to step S4.5, otherwise return to step S4.2. Step S4.4 is used to check the grid quality independence, so that the simulation result no longer significantly depends on the refinement degree of the grid, and the reliability of the simulation result is ensured.

[0050] S4.5, simulate multiple outlet flow conditions by CFD software and obtain the boost value corresponding to the flow condition, and draw a flow boost curve. The flow size of the multiple outlet flow conditions at least includes 0 times, 0.2 times, 0.4 times, 0.6 times, 0.8 times, 1.0 times and 1.2 times of the rated flow. By simulating multiple flow conditions, it is ensured that the design can maintain good performance under different working conditions, and the robustness and adaptability of the design are improved.

[0051] S4.6, obtain the boost value under the rated flow through the flow boost curve.

[0052] In this embodiment, the setting of the boundary conditions includes setting the boundary condition of the volute inlet as pressure inlet, setting the total pressure of the known fluid entering the volute as an input parameter, and specifying the inlet pressure, so that the solver can calculate the flow characteristics entering the system according to the fluid dynamics equation. The boundary condition of the volute outlet is mass flow, and by specifying the mass flow, the solver can calculate the appropriate flow velocity and pressure according to the internal flow field conditions. The boundary condition of the exhaust pipe outlet is pressure outlet, and the pressure of the exhaust pipe is set to be equal to the pressure of the volute inlet to ensure the physical consistency of the system. The solid wall of the volute adopts a no-slip wall surface, and the no-slip wall surface condition makes the velocity of the fluid on the wall surface the same as the wall surface velocity, which can effectively simulate the interaction between the fluid and the solid surface and capture the formation and development of the boundary layer. The near-wall region adopts the stretching wall function method, which is an approximate method for processing turbulent flow near the wall. It describes the velocity distribution near the wall through an empirical formula or function, thereby avoiding the use of too fine grid near the wall. It can be automatically adjusted according to the density of the grid to ensure the stability and accuracy of the calculation results. The dynamic and static interface between the impeller and the volute adopts the frozen rotor method. The frozen rotor method is a simplified method for processing the interface between the dynamic and static parts in a rotating machine. By assuming that the relative position between the impeller and the volute is fixed during the calculation process, the dynamic problem is approximated as a steady-state problem for processing. This method greatly simplifies the calculation, and when the rotational speed is relatively stable, it can provide relatively accurate results.

[0053] Embodiment 2

[0054] This embodiment is a further limitation based on embodiment 1, and the specific improvement point is how to design a fuel pump with a rated flow of 150 L / h, a rotational speed of 9000 r / min, a boost pressure of 60 kPa, and a maximum flight altitude of 10,000 meters. The other parts not mentioned refer to embodiment 1 or the prior art.

[0055] According to the air type cavitation active control method of the fuel pump, the impeller inlet diameter D1 is 8 mm; the impeller outlet diameter D2 is 28 mm; the impeller outlet width b2 is 2.5 mm; the number of blades Z is 6; the blade wrap angle γ is 120°, the blade inlet installation angle β1 is 20°, and the blade inlet installation angle β2 is 30°; the volute base circle diameter is 29 mm; the volute width is 7 mm; and the volute outlet diameter is 8 mm. The exhaust hole diameter is determined to be 5 mm.

[0056] The boundary conditions are set, and 9 working conditions of 0 L / h, 30 L / h, 60 L / h, 90 L / h, 120 L / h, 150 L / h, 180 L / h, 210 L / h, 240 L / h and 270 L / h are simulated, and the flow boost curve obtained is as shown in Figure 3The pressure is increased by 64.1 kPa, which meets the design requirement. Finally, the fuel pump is designed as a pipeline type according to the use requirement, and the reference Figure 2 The inlet and outlet of the fuel pump are sealed by O-rings, and the exhaust passage is introduced into the fuel tank by a pipeline.

[0057] Although the specific embodiments of the invention are described in detail with reference to the accompanying drawings, it should not be understood as limiting the scope of protection of the patent. Various modifications and variations made by those skilled in the art within the scope described in the claims are still within the scope of protection of the patent.

Claims

1. A method for actively controlling air-type cavitation in a fuel pump, characterized in that: Including steps: S1. Determine the fuel pump performance parameters based on the aircraft's altitude and fuel requirements. The performance parameters include rated flow. , rated boost , speed and cavitation margin ; S2. Calculate the hydraulic parameters of the impeller and volute in the fuel pump based on the performance parameters of the fuel pump; S3. Establish a three-dimensional model of the impeller and the volute based on the hydraulic parameters of the impeller and the volute, and model an exhaust pipe for communicating with the fuel tank on the volute oil outlet pipe of the three-dimensional model; S4. Perform numerical simulation on the three-dimensional model and continuously increase the diameter of the exhaust pipe within the set threshold range of the exhaust pipe diameter to obtain the boost value at the rated flow rate for different exhaust pipe diameters. ; S5. Determine whether there is a boost value Greater than or equal to rated boost pressure If yes, then go to step S6, otherwise increase the rated flow in the performance parameters of the fuel pump And return to step S2; S6. Acquisition and boosting value The corresponding exhaust pipe diameter is determined, and the fuel pump is processed according to the minimum diameter of the exhaust pipe and the parameters of the three-dimensional model.

2. The method for actively controlling air-type cavitation in a fuel pump according to claim 1, characterized in that: The exhaust pipe in the 3D model is vertically connected to the volute oil outlet pipe.

3. The method for actively controlling air cavitation in a fuel pump according to claim 2, wherein: Exhaust pipe diameter d The setting threshold range is: when the rated flow hour, ; When rated flow hour, .

4. The method for actively controlling air cavitation in a fuel pump according to claim 2, wherein: The method for numerical simulation of three-dimensional models is: S4.

1. Perform preliminary meshing of the 3D model using CFD software; S4.

2. Set up a turbulence model in the flow channel within the three-dimensional model; S4.

3. Set the boundary conditions of the 3D model and use the fuel medium JET A Liquid to solve the single-phase flow to obtain the test boost value of the 3D model; S4.

4. Increase the mesh density of the three-dimensional model and obtain the test boost value of the three-dimensional model again; S4.

5. Compare the two test boost values ​​to see if the change is less than 5%. If so, proceed to step S4.6; otherwise, return to step S4.

2. S4.

6. Use CFD software to simulate multiple outlet flow conditions of the three-dimensional model and obtain the corresponding pressure boost values ​​under these conditions, and draw flow and pressure boost curves; S4.

7. Obtain the boost pressure value at the rated flow rate through the flow boost pressure curve.

5. The method for actively controlling air cavitation in a fuel pump according to claim 4, characterized in that: The turbulence model is the RNG k-ε turbulence model or the SST k-ω turbulence model.

6. The method for actively controlling air cavitation in a fuel pump according to claim 4, characterized in that: The boundary conditions are as follows: the boundary condition of the volute inlet is the pressure inlet, the boundary condition of the volute outlet is the mass flow rate, the boundary condition of the exhaust duct outlet is the pressure outlet, the solid wall of the volute adopts the no-slip wall method, the near-wall area adopts the telescopic wall function method, and the dynamic and static interface between the impeller and the volute adopts the frozen rotor method.

7. The method for actively controlling air cavitation in a fuel pump according to claim 4, wherein: The convergence accuracy of the residual error of the fuel medium JETA Liquid is 10 -5 .

8. The method for actively controlling air cavitation in a fuel pump according to claim 4, wherein: The flow sizes of the multiple outlet flow conditions include at least 0 times, 0.2 times, 0.4 times, 0.6 times, 0.8 times, 1.0 times and 1.2 times the rated flow.

9. The method for actively controlling air cavitation in a fuel pump according to claim 1, wherein: The hydraulic parameters of the impeller include the impeller inlet diameter, impeller outlet diameter, impeller outlet width, number of blades, blade wrap angle, and blade inlet placement angle.

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