Liquid rocket engine centrifugal pump-pipeline operation characteristic simulation determination method, system and equipment under variable load working condition and medium

Abstract

The invention discloses a liquid rocket engine centrifugal pump-pipeline operation characteristic simulation determination method, system and device under a variable load working condition and a medium, and relates to the technical field of liquid rocket engine modeling simulation. The method comprises the steps that a lumped parameter mathematical model and a centrifugal pump dynamics mathematical model of a propellant supply pipeline of the liquid rocket engine are established; based on the lumped parameter mathematical model of the propellant supply pipeline and the centrifugal pump dynamics mathematical model, a corresponding propellant supply pipeline simulation model and a corresponding centrifugal pump simulation model are built in Simulink; and respectively inputting different load working condition parameters into the propellant supply pipeline simulation model and the centrifugal pump simulation model to respectively obtain corresponding operation characteristics of the propellant supply pipeline and the centrifugal pump under different load working condition parameter conditions. According to the method, the accuracy of the liquid rocket engine centrifugal pump-pipeline operation characteristic simulation result is improved.

Description

Technical Field

[0001] The present application relates to the technical field of liquid rocket engine modeling and simulation, and in particular to a method, system, equipment and medium for simulating and determining the operating characteristics of a liquid rocket engine centrifugal pump-pipeline under variable load conditions. Background Art

[0002] In the field of modern aerospace, liquid rocket engines are the core of the propulsion system, and their performance and reliability requirements are extremely high. Pipeline systems and centrifugal pumps are indispensable components of liquid rocket engines. Together, they ensure that fuel and oxidizer can be efficiently and stably delivered to the combustion chamber. Liquid rocket engines are actually a thermodynamic fluid network system that connects some typical components with pipelines, and fluid dynamics in the propellant supply pipeline is one of its important research contents. At the same time, centrifugal pumps have the advantages of high efficiency, adaptability to high flow requirements, and compact structure, so they have been widely used in liquid rocket engines. With the increasing complexity of aerospace missions, the performance stability and reliability requirements of centrifugal pumps and piping systems are also constantly increasing. Through simulation modeling of centrifugal pumps and piping systems, the performance of the system under different working conditions can be predicted and analyzed without actual manufacturing and testing, thereby guiding the optimization of the design. This can not only significantly reduce R&D costs, but also discover potential design problems in advance and ensure the reliability and safety of the engine. However, there is still a certain degree of uncertainty in the operating characteristics of centrifugal pumps and piping systems under variable load conditions. These systems must be able to adapt to the changes in demand at different stages such as the start-up, operation, and shutdown of liquid rocket engines, and maintain efficient and stable output. Therefore, in-depth research on the performance of these key components under different working conditions and the establishment of accurate simulation models are of great significance to improving the overall performance and reliability of liquid rocket engines. Summary of the invention

[0003] The purpose of this application is to provide a method, system, equipment and medium for simulating and determining the operating characteristics of a liquid rocket engine centrifugal pump-pipeline under variable load conditions, thereby improving the accuracy of the simulation results of the operating characteristics of a liquid rocket engine centrifugal pump-pipeline.

[0004] To achieve the above objectives, this application provides the following solutions:

[0005] In a first aspect, the present application provides a method for simulating and determining the operating characteristics of a centrifugal pump-pipeline of a liquid rocket engine under variable load conditions, the method comprising:

[0006] Establish a lumped parameter mathematical model of the propellant supply pipeline of the liquid rocket engine and a centrifugal pump dynamic mathematical model; the lumped parameter mathematical model of the propellant supply pipeline is established based on the fluid motion characteristic equation considering the fluid inertia factor and the fluid motion characteristic equation considering the fluid local resistance factor; the centrifugal pump dynamic mathematical model includes: a centrifugal pump inlet end face and diffuser outlet end face mass flow transfer model, a centrifugal pump inlet and outlet liquid pressure difference change model and a centrifugal pump inlet and outlet liquid temperature difference change model;

[0007] Based on the lumped parameter mathematical model of the propellant supply pipeline and the centrifugal pump dynamic mathematical model, respectively, a corresponding propellant supply pipeline simulation model and a centrifugal pump simulation model are built in Simulink;

[0008] Input different load condition parameters into the propellant supply pipeline simulation model to obtain the corresponding operating characteristics of the propellant supply pipeline under different load condition parameters; the load condition parameters include: liquid circuit fluid pressure, mass flow rate and temperature conditions;

[0009] Different load condition parameters are input into the centrifugal pump simulation model to obtain the corresponding operating characteristics of the centrifugal pump under different load condition parameters.

[0010] Optionally, the process of establishing the lumped parameter mathematical model of the propellant supply pipeline specifically includes:

[0011] Establish the characteristic equation of fluid motion taking into account the fluid inertia factor;

[0012] Establish the characteristic equation of fluid motion taking into account the local resistance factor of the fluid;

[0013] Based on the fluid motion characteristic equation considering the fluid inertia factor and the fluid motion characteristic equation considering the fluid local resistance factor, a group of fluid flow characteristic equations considering both the fluid inertia factor and the fluid local resistance factor are obtained;

[0014] The fluid motion characteristic equations in the fluid flow characteristic equation group that considers both the fluid inertia factor and the fluid local resistance factor are solved simultaneously to obtain a lumped parameter mathematical model of the propellant supply pipeline.

[0015] Optionally, the expression of the fluid motion characteristic equation considering the fluid inertia factor is:

[0016]

[0017] Wherein, G is the mass flow rate of the liquid in the flow path; t is the time; A is the minimum flow area at the local resistance; L is the length of the flow path segment; P1 is the inlet pressure of the flow path segment; P2 is the outlet pressure of the flow path segment;

[0018] The expression of the fluid motion characteristic equation considering the local resistance factor of the fluid is:

[0019]

[0020] in, is the flow resistance coefficient when the valve is fully opened; μ is the flow coefficient; It is the product of μ and A when the valve is fully open.

[0021] Optionally, the expression of the fluid flow characteristic equation taking into account both the fluid inertia factor and the fluid local resistance factor is as follows:

[0022] P in -P1=R1·G 2 ;

[0023]

[0024]

[0025]

[0026] P4-P out =R3·G 2 ;

[0027] Among them, P in is the fluid pressure before passing through the inlet local resistance; R1 is the first local resistance; L1 is the flow path segment length between the first fixed local resistance and the second adjustable local resistance; P3 is the fluid pressure after passing through the adjustable valve; is the second local resistance when the valve is fully opened; P4 is the fluid pressure before passing through the outlet local resistance; L2 is the flow path segment length between the second adjustable local resistance and the third fixed local resistance; P out is the fluid pressure after passing through the outlet local resistance; R3 is the third local resistance.

[0028] Optionally, the expression of the lumped parameter mathematical model of the propellant supply pipeline is:

[0029]

[0030] Optionally, the process of establishing the centrifugal pump dynamic mathematical model specifically includes:

[0031] Based on the actual connection relationship between the rotor and the inducer during the operation of the centrifugal pump, the mass flow transfer model between the inlet end face of the centrifugal pump and the outlet end face of the diffuser is determined;

[0032] Based on the dynamic relationship of the supply liquid flowing through the centrifugal pump, a model for the change of the liquid pressure difference between the inlet and outlet of the centrifugal pump is determined;

[0033] Based on the dynamic relationship of the supply liquid flowing through the centrifugal pump, a model for the change of the liquid temperature difference between the inlet and outlet of the centrifugal pump is determined.

[0034] Alternatively, the expression of the mass flow transfer model at the centrifugal pump inlet end face and the diffuser outlet end face is:

[0035]

[0036] in, is the inlet mass flow rate of the inducer; is the mass flow rate at the diffuser outlet;

[0037] The expression of the centrifugal pump inlet and outlet liquid pressure difference change model is:

[0038] P l2 =P l1 +ΔP l ;

[0039]

[0040] Among them, P l2 is the centrifugal pump outlet pressure; P l1 is the centrifugal pump inlet pressure; ΔP l is the dynamic pressure head of the centrifugal pump; ΔP s is the steady-state pressure head of the centrifugal pump; A m , A n is a constant related to the centrifugal pump structure and propellant density; is the mass flow rate; n is the speed of the centrifugal pump;

[0041] The expression of the centrifugal pump inlet and outlet liquid temperature difference change model is:

[0042]

[0043] Where T is the liquid temperature; t i is the coefficient to be fitted; p is the liquid pressure; ρ is the liquid density.

[0044] In a second aspect, the present application provides a system for simulating and determining the operating characteristics of a centrifugal pump-pipeline of a liquid rocket engine under variable load conditions. The system for simulating and determining the operating characteristics of a centrifugal pump-pipeline of a liquid rocket engine under variable load conditions is used to implement the method for simulating and determining the operating characteristics of a centrifugal pump-pipeline of a liquid rocket engine under variable load conditions. The system for simulating and determining the operating characteristics of a centrifugal pump-pipeline of a liquid rocket engine under variable load conditions includes:

[0045] A model building unit is used to build a lumped parameter mathematical model of a propellant supply pipeline of a liquid rocket engine and a centrifugal pump dynamic mathematical model; the lumped parameter mathematical model of the propellant supply pipeline is built based on a fluid motion characteristic equation that takes into account a fluid inertia factor and a fluid motion characteristic equation that takes into account a fluid local resistance factor; the centrifugal pump dynamic mathematical model includes: a centrifugal pump inlet end face and a diffuser outlet end face mass flow transfer model, a centrifugal pump inlet and outlet liquid pressure difference change model, and a centrifugal pump inlet and outlet liquid temperature difference change model;

[0046] A model building unit, used to build a corresponding propellant supply pipeline simulation model and a centrifugal pump simulation model in Simulink based on the lumped parameter mathematical model of the propellant supply pipeline and the centrifugal pump dynamics mathematical model respectively;

[0047] A propellant supply pipeline operation characteristic determination unit is used to input different load condition parameters into the propellant supply pipeline simulation model to obtain the corresponding operation characteristics of the propellant supply pipeline under different load condition parameters; the load condition parameters include: liquid circuit fluid pressure, mass flow and temperature conditions;

[0048] The centrifugal pump operation characteristic determination unit is used to input different load condition parameters into the centrifugal pump simulation model to obtain the corresponding operation characteristics of the centrifugal pump under different load condition parameters.

[0049] In a third aspect, the present application provides a computer device comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the method for simulating and determining the operating characteristics of a centrifugal pump-pipeline of a liquid rocket engine under variable load conditions as described in any one of the above items.

[0050] In a fourth aspect, the present application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method for simulating and determining the operating characteristics of a centrifugal pump-pipeline of a liquid rocket engine under variable load conditions as described in any of the above items.

[0051] According to the specific embodiments provided in this application, this application has the following technical effects:

[0052] The present application discloses a method, system, equipment and medium for simulating and determining the operating characteristics of a centrifugal pump-pipeline of a liquid rocket engine under variable load conditions. By establishing a lumped parameter mathematical model of the propellant supply pipeline of the liquid rocket engine and a centrifugal pump dynamics mathematical model, a centrifugal pump fluid dynamics model that is easy to connect with the finite element state variables of the distributed fluid pipeline is obtained, which can more accurately describe the flow characteristics of the liquid in the supply pipeline and the centrifugal pump, thereby improving the accuracy of the simulation results of the operating characteristics of the centrifugal pump-pipeline of the liquid rocket engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0054] Figure 1 A schematic flow chart of a method for simulating and determining the operating characteristics of a liquid rocket engine centrifugal pump-pipeline under variable load conditions provided in one embodiment of the present application;

[0055] Figure 2 This is a schematic diagram considering the inertia factor and local resistance factor of the fluid in the supply pipeline;

[0056] Figure 3 A schematic diagram of a centrifugal pump provided in one embodiment of the present application;

[0057] Figure 4 A schematic diagram of a simulation model for calculating ΔP during the simulation of the fluid pressure difference in the supply pipeline;

[0058] Figure 5 It is a schematic diagram of the simulation model of the pressure change of the fluid inlet and outlet in the supply pipeline;

[0059] Figure 6 It is a schematic diagram of the simulation model of the temperature change of the fluid inlet and outlet in the supply pipeline;

[0060] Figure 7 This is a schematic diagram of the super element of the propellant supply pipeline module;

[0061] Figure 8 It is a simulation model diagram for calculating ΔP during the simulation process of the fluid pressure difference in the centrifugal pump;

[0062] Fig. 9 It is a schematic diagram of the simulation model of the inlet and outlet pressure changes of the fluid in the centrifugal pump;

[0063] Fig.10 It is a schematic diagram of the simulation model of the temperature change of the fluid inlet and outlet in the centrifugal pump;

[0064] Fig.11 It is a schematic diagram of the super element of the centrifugal pump module;

[0065] Fig.12 This is a schematic diagram of the change in the speed of a centrifugal pump with a load added;

[0066] Fig.13 This is a schematic diagram of the temperature change of liquid oxygen output by the turbo pump;

[0067] Fig.14 A schematic diagram of the structure of a computer device provided in one embodiment of the present application. DETAILED DESCRIPTION

[0068] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0069] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0070] In an exemplary embodiment, Figure 1 As shown, a method for simulating and determining the operating characteristics of a liquid rocket engine centrifugal pump-pipeline under variable load conditions is provided, comprising the following steps S1 to S4. Among them:

[0071] Step S1, establishing a lumped parameter mathematical model of a propellant supply pipeline of a liquid rocket engine and a centrifugal pump dynamic mathematical model; the lumped parameter mathematical model of the propellant supply pipeline is established based on a fluid motion characteristic equation that considers a fluid inertia factor and a fluid motion characteristic equation that considers a fluid local resistance factor; the centrifugal pump dynamic mathematical model includes: a centrifugal pump inlet end face and a diffuser outlet end face mass flow transfer model, a centrifugal pump inlet and outlet liquid pressure difference change model, and a centrifugal pump inlet and outlet liquid temperature difference change model.

[0072] As an optional implementation, in step S1, the process of establishing the lumped parameter mathematical model of the propellant supply pipeline specifically includes:

[0073] Step S111, establishing a fluid motion characteristic equation taking into account the fluid inertia factor.

[0074] Specifically, the main influencing factors of the dynamic characteristics of the propellant supply pipeline are divided into fluid inertia factors and local resistance factors with similar influence magnitudes, such as Figure 2As shown in the figure, based on the assumption that the flow path segment is filled with inviscid and incompressible liquid, the characteristic equation of fluid motion considering the fluid inertia factor is derived:

[0075]

[0076] Among them, A is the minimum flow area at the local resistance; P1 is the inlet pressure of the flow path segment; P2 is the outlet pressure of the flow path segment; m is the mass of the liquid in the flow path; u is the flow velocity of the liquid; t is time; ρ is the density of the liquid; L is the length of the flow path segment; G is the mass flow rate of the liquid in the flow path.

[0077] Then the expression of the characteristic equation of fluid motion considering the fluid inertia factor is obtained as follows:

[0078]

[0079] Step S112, establishing a fluid motion characteristic equation that takes into account the local resistance factor of the fluid.

[0080] The local resistance pressure difference ΔP = P1-P2 is proportional to the square of the liquid mass flow rate G in the flow path. Ignoring the inertia of the liquid, it can be expressed as:

[0081]

[0082]

[0083]

[0084] Then the expression of the characteristic equation of fluid motion considering the local resistance factor of the fluid is obtained:

[0085]

[0086] in, is the flow resistance coefficient when the valve is fully opened; μ is the flow coefficient; It is the product of μ and A when the valve (adjustable local resistance) is fully open; R is the flow resistance coefficient.

[0087] Step S113, based on the fluid motion characteristic equation considering the fluid inertia factor and the fluid motion characteristic equation considering the fluid local resistance factor, a group of fluid flow characteristic equations considering both the fluid inertia factor and the fluid local resistance factor are obtained.

[0088] As an optional implementation, the expressions of the fluid flow characteristic equations taking into account both the fluid inertia factor and the fluid local resistance factor are as follows (7)-(11), and the derivation process is as follows:

[0089] Specifically, considering the most general case, it is assumed that there is a fixed local resistance at the inlet and outlet of the flow path, an adjustable valve is installed in the middle of the flow path, and the friction loss (viscosity) of the fluid is equivalent to the local resistance at both ends.

[0090] The first local resistance is:

[0091] P in -P1=R1·G 2 (7)

[0092] Among them, R1 is the first local resistance; P in is the fluid pressure before passing through the local resistance at the inlet.

[0093] For the flow path segment between the first fixed local resistance and the second adjustable local resistance (length L1), we have:

[0094]

[0095] The second adjustable local resistance is:

[0096]

[0097] in, is the flow resistance coefficient when the valve is fully opened; It is the product of μ and A when the valve is fully open; P3 is the fluid pressure after passing through the adjustable valve.

[0098] For the flow path segment between the second adjustable local resistance and the third fixed local resistance (length L2), we have:

[0099]

[0100] Wherein, P4 is the fluid pressure before passing through the local resistance at the outlet;

[0101] The third local resistance is:

[0102] P4-P out =R3·G 2 (11)

[0103] Among them, P out is the fluid pressure after passing through the outlet local resistance, and R3 is the third local resistance.

[0104] Step S114, solving the fluid motion characteristic equations in the fluid flow characteristic equation group that considers both the fluid inertia factor and the fluid local resistance factor simultaneously, and obtaining a lumped parameter mathematical model of the propellant supply pipeline.

[0105] Specifically, by adding equations (7)-(11) above and sorting them out, the expression of the lumped parameter mathematical model of the propellant supply pipeline can be obtained as follows:

[0106]

[0107] As an optional implementation, in step S1, the process of establishing the centrifugal pump dynamic mathematical model specifically includes:

[0108] Step S121, based on the actual connection relationship between the rotor and the inducer during the operation of the centrifugal pump, a mass flow transfer model between the inlet end face of the centrifugal pump and the outlet end face of the diffuser is determined.

[0109] like Figure 3 As shown in the figure, the volume between the centrifugal pump inlet end face and the inducer inlet end face is regarded as the concentrated volume, and the relationship between the centrifugal pump inlet mass flow rate and the diffuser outlet mass flow rate is derived. In order to take into account the volumetric effect of the inducer, impeller and diffuser, the equivalent volume of the concentrated volume is: Among them, V1 is the flow channel volume between the inlet end face of the centrifugal pump and the inlet end face of the centrifugal pump inducer, V I is the aisle volume of the inducer, V W is the passage volume of the impeller, V D is the diffuser passage volume. It can be assumed that the inducer inlet mass flow Mass flow rate at the diffuser outlet are always equal, and the expression of the mass flow transfer model of the centrifugal pump inlet end face and the diffuser outlet end face is obtained as follows:

[0110]

[0111] in, is the inlet mass flow rate of the inducer; is the mass flow rate at the diffuser outlet.

[0112] Step S122, based on the dynamic relationship of the supply liquid flowing through the centrifugal pump, determine the liquid pressure difference change model at the inlet and outlet of the centrifugal pump.

[0113] Specifically, the characteristic equation of fluid flow in a centrifugal pump is as follows:

[0114] Since the centrifugal pump inlet pressure is low, the density change of the inlet propellant is not considered. The flow capacity equation based on the concentrated volume is:

[0115]

[0116] Among them, q in and q1 are the flow rates at the centrifugal pump inlet end face and the centrifugal pump inducer inlet end face, respectively. pumpis the equivalent flow capacity C of the concentrated volume at the inlet pump =V pump / (ρ in a 2 ), a is the propellant wave velocity, and the inlet pressure P can be obtained by integration in .

[0117] Power and efficiency of centrifugal pumps:

[0118] Power of centrifugal pump P w Including steady-state power P sw and dynamic power P dw :

[0119]

[0120] Among them, T w is the torque of the centrifugal pump.

[0121] Steady-state power P of centrifugal pump sw for:

[0122]

[0123] Among them, T s is the steady-state torque of the centrifugal pump.

[0124] Dynamic power P of centrifugal pump dw for:

[0125]

[0126] Among them, J m , J n is a constant coefficient related to the propellant density.

[0127] Efficiency η of a centrifugal pump p for:

[0128]

[0129] Among them, ΔP l is the dynamic pressure head of the centrifugal pump; is the correction factor related to the cavitation volume; q is the propellant flow rate.

[0130] The expression of the centrifugal pump inlet and outlet liquid pressure difference change model is obtained as follows:

[0131] P l2 =P l1 +ΔP l (19)

[0132]

[0133] Among them, Pl2 is the centrifugal pump outlet pressure; P l1 is the centrifugal pump inlet pressure; ΔP l is the dynamic pressure head of the centrifugal pump; ΔP s is the steady-state pressure head of the centrifugal pump; A m , A n is a constant related to the centrifugal pump structure and propellant density; is the average mass flow rate of the centrifugal pump; n is the speed of the centrifugal pump.

[0134] Specifically, during transient processes such as engine startup and shutdown, the effects of the mass flow rate change and speed change rate on the centrifugal pump head need to be taken into account:

[0135]

[0136] The outlet pressure of the centrifugal pump is shown in formula (19).

[0137] Step S123, based on the dynamic relationship of the supply liquid flowing through the centrifugal pump, determine a model for the change in the temperature difference between the inlet and outlet liquids of the centrifugal pump.

[0138] Among them, the expression of the centrifugal pump inlet and outlet liquid temperature difference change model is:

[0139]

[0140] Where T is the temperature of the liquid to be calculated; t i (i=0,1,…,6) is the coefficient to be fitted, which can be obtained from the least square fitting coefficient table obtained from experimental data; p is the liquid pressure; ρ is the liquid density. l Substituting into the formula, we can get the propellant temperature at the centrifugal pump outlet.

[0141] Step S2, building a corresponding propellant supply pipeline simulation model and a centrifugal pump simulation model in Simulink based on the lumped parameter mathematical model of the propellant supply pipeline and the centrifugal pump dynamics mathematical model, respectively.

[0142] Specifically, the schematic diagram of the simulation model of the propellant supply pipeline is as follows: Figure 4 and Figure 5 As shown in the figure, the pressure difference variation model of the flow path segment inlet and outlet, the mass flow model inside the propellant supply pipeline, and the temperature variation model of the flow path segment inlet and outlet are as follows: Figure 6 As shown in FIG. 1 , a fixed-length supply pipeline model is used as a super element, and the input and output parameters of the propellant supply pipeline super element are set: the input parameters include the inlet pressure, temperature and mass flow rate of the liquid in the supply pipeline; the output parameters include the outlet pressure, temperature and mass flow rate of the liquid in the supply pipeline. The schematic diagram of the propellant supply pipeline super element is shown in FIG. Figure 7shown.

[0143] According to the actual connection relationship between the rotor and the inducer during the operation of the centrifugal pump and the dynamic relationship of the supply liquid flowing through the centrifugal pump, a centrifugal pump model is established, such as Figure 8 As shown; specifically including: the mass flow transfer model of the centrifugal pump inlet end face and the diffuser outlet end face, the centrifugal pump inlet and outlet liquid pressure difference change model, the centrifugal pump inlet and outlet liquid temperature difference change model, such as Fig. 9 and Fig.10 As shown. The single centrifugal pump model is encapsulated as a subsystem to form a super component, and the centrifugal pump super component interface is set: the input parameters are the rotor speed connected to the centrifugal pump, the centrifugal pump inlet liquid pressure, temperature and mass flow, etc.; the output parameters are the centrifugal pump outlet liquid pressure, temperature and mass flow, etc., and the centrifugal pump super component schematic diagram is as shown Fig.11 shown.

[0144] Step S3, inputting different load condition parameters into the propellant supply pipeline simulation model to obtain the corresponding operating characteristics of the propellant supply pipeline under different load condition parameters; the load condition parameters include: liquid circuit fluid pressure, mass flow and temperature conditions.

[0145] Specifically, considering that the commonly used propellants for liquid rocket engines are liquid hydrogen and liquid oxygen, the corresponding liquid characteristic parameters are input into the propellant supply pipeline model: liquid hydrogen: inlet pressure 0.249MPa, inlet temperature 20.3K, mass flow rate 3.112kg / s; liquid oxygen: inlet pressure 0.283MPa, inlet temperature 89K, mass flow rate 15.991kg / s.

[0146] Then, the liquid pressure, mass flow rate and temperature characteristics of the propellant supply pipeline under different liquid circuit fluid pressure, mass flow rate and temperature conditions are obtained.

[0147] Step S4, inputting different load condition parameters into the centrifugal pump simulation model to obtain the corresponding operating characteristics of the centrifugal pump under different load condition parameters.

[0148] Specifically, the centrifugal pump input rotor speed is set to 14000r / min, and the corresponding liquid characteristic parameters are input into the centrifugal pump model: liquid hydrogen: inlet pressure 0.255MPa, inlet temperature 21.5K, mass flow rate 3.112kg / s, inlet density 69.58kg / m3, efficiency 0.519; liquid oxygen: inlet pressure 0.294MPa, inlet temperature 92K, mass flow rate 15.991kg / s, inlet density 1132.4kg / m3, efficiency 0.692.

[0149] The output fluid pressure, mass flow rate and temperature characteristics of the centrifugal pump under the conditions of a certain rotor speed, different input fluid pressure, mass flow rate and temperature are obtained.

[0150] At present, the fluid flow through the turbine pump is a complex three-dimensional motion, which is generally described by the Navier-Stokes equations. When it comes to engine system analysis and control, the three-dimensional NS equations of the turbine pump are too complex and therefore need to be simplified for practical application. In recent years, when studying the dynamic characteristics of engine systems, steady-state relationships are mostly used for centrifugal pumps. However, when connected to the finite element state variable model of the pipeline, the processing of boundary conditions is more cumbersome and is not suitable for modular segmentation of distributed parameter pipeline systems. The present application establishes a turbine pump fluid dynamics model that is easy to connect to the finite element state variables of the distributed fluid pipeline by dividing the finite control volume at the inlet and outlet pipelines of the turbine pump (i.e., centrifugal pump), which can more accurately describe the flow characteristics of the liquid in the supply pipeline and the centrifugal pump.

[0151] Furthermore, after establishing the propellant supply pipeline simulation model and the centrifugal pump simulation model, it is necessary to test their operation under different loads. Fig.12 The change in the speed of the centrifugal pump after adding load can show the influence of load on the speed of the centrifugal pump. Fig.13 The temperature of the liquid oxygen output by the turbine changes after the supply liquid passes through the pipeline-centrifugal pump. Since the centrifugal pump is connected to the turbine, the temperature change also represents the temperature change of the liquid in the entire model to a certain extent, which verifies the simulation results of the model for temperature fitting.

[0152] The beneficial technical effects of this application compared with the related art are:

[0153] 1. The method for simulating and determining the operating characteristics of the centrifugal pump-pipeline of a liquid rocket engine under variable load conditions provided in this application is based on a realistic physical model, and a propellant supply pipeline simulation model and a centrifugal pump simulation model are established, which can quantitatively analyze the liquid flow characteristics in the supply pipeline and the centrifugal pump.

[0154] 2. This application fully considers the influence of fluid inertia and local resistance in the supply pipeline and the flow relationship between the liquid at the inlet of the centrifugal pump inducer and the liquid at the outlet of the diffuser. The proposed simulation calculation method can more accurately describe the flow characteristics of the liquid in the supply pipeline and the centrifugal pump compared with other calculation methods.

[0155] Based on the same inventive concept, the embodiment of the present application also provides a system for simulating and determining the operating characteristics of a centrifugal pump-pipeline of a liquid rocket engine under variable load conditions, which is used to implement the method for simulating and determining the operating characteristics of a centrifugal pump-pipeline of a liquid rocket engine under variable load conditions. The implementation scheme for solving the problem provided by the system is similar to the implementation scheme recorded in the above method, so the specific limitations in the embodiments of the system for simulating and determining the operating characteristics of a centrifugal pump-pipeline of a liquid rocket engine under variable load conditions provided below can be referred to the limitations of the method for simulating and determining the operating characteristics of a centrifugal pump-pipeline of a liquid rocket engine under variable load conditions, which will not be repeated here.

[0156] In an exemplary embodiment, a system for simulating and determining the operating characteristics of a centrifugal pump-pipeline of a liquid rocket engine under variable load conditions is provided, comprising:

[0157] The model building unit is used to build a lumped parameter mathematical model of a propellant supply pipeline of a liquid rocket engine and a centrifugal pump dynamic mathematical model; the lumped parameter mathematical model of the propellant supply pipeline is built based on a fluid motion characteristic equation that takes into account a fluid inertia factor and a fluid motion characteristic equation that takes into account a fluid local resistance factor; the centrifugal pump dynamic mathematical model includes: a centrifugal pump inlet end face and a diffuser outlet end face mass flow transfer model, a centrifugal pump inlet and outlet liquid pressure difference change model, and a centrifugal pump inlet and outlet liquid temperature difference change model.

[0158] The model building unit is used to build a corresponding propellant supply pipeline simulation model and a centrifugal pump simulation model in Simulink based on the lumped parameter mathematical model of the propellant supply pipeline and the centrifugal pump dynamics mathematical model respectively.

[0159] The propellant supply pipeline operation characteristic determination unit is used to input different load condition parameters into the propellant supply pipeline simulation model to obtain the corresponding operation characteristics of the propellant supply pipeline under different load condition parameters; the load condition parameters include: liquid circuit fluid pressure, mass flow and temperature conditions.

[0160] The centrifugal pump operation characteristic determination unit is used to input different load condition parameters into the centrifugal pump simulation model to obtain the corresponding operation characteristics of the centrifugal pump under different load condition parameters.

[0161] In an exemplary embodiment, a computer device is provided, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement a method for simulating and determining operating characteristics of a centrifugal pump-pipeline of a liquid rocket engine under variable load conditions.

[0162] In an exemplary embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, a method for simulating and determining the operating characteristics of a centrifugal pump-pipeline of a liquid rocket engine under variable load conditions is implemented.

[0163] In an exemplary embodiment, a computer device is provided. The computer device may be a server or a terminal. The internal structure diagram thereof may be as follows: Fig.14 As shown. The computer device includes a processor, a memory, an input / output interface (Input / Output, referred to as I / O) and a communication interface. Among them, the processor, the memory and the input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The input / output interface of the computer device is used to exchange information between the processor and an external device. The communication interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, a method for simulating and determining the operating characteristics of a liquid rocket engine centrifugal pump-pipeline under variable load conditions is implemented.

[0164] Those skilled in the art will understand that Fig.14 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0165] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with relevant regulations.

[0166] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in the present application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM may be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0167] The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. The non-relational database may include a distributed database based on blockchain, etc., but is not limited thereto. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., but is not limited thereto.

[0168] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0169] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A method for simulating and determining the operating characteristics of a liquid rocket engine centrifugal pump-pipeline under variable load conditions, characterized in that: The method for simulating and determining the operating characteristics of a liquid rocket engine centrifugal pump-pipeline under variable load conditions includes: Establish a lumped parameter mathematical model of the propellant supply pipeline of the liquid rocket engine and a centrifugal pump dynamic mathematical model; the lumped parameter mathematical model of the propellant supply pipeline is established based on the fluid motion characteristic equation considering the fluid inertia factor and the fluid motion characteristic equation considering the fluid local resistance factor; the centrifugal pump dynamic mathematical model includes: a centrifugal pump inlet end face and diffuser outlet end face mass flow transfer model, a centrifugal pump inlet and outlet liquid pressure difference change model and a centrifugal pump inlet and outlet liquid temperature difference change model; Based on the lumped parameter mathematical model of the propellant supply pipeline and the centrifugal pump dynamic mathematical model, respectively, a corresponding propellant supply pipeline simulation model and a centrifugal pump simulation model are built in Simulink; Input different load condition parameters into the propellant supply pipeline simulation model to obtain the corresponding operating characteristics of the propellant supply pipeline under different load condition parameters; the load condition parameters include: liquid circuit fluid pressure, mass flow rate and temperature conditions; Different load condition parameters are input into the centrifugal pump simulation model to obtain the corresponding operating characteristics of the centrifugal pump under different load condition parameters.

2. The method for simulating and determining the operating characteristics of a liquid rocket engine centrifugal pump-pipeline under variable load conditions according to claim 1 is characterized in that: The process of establishing the lumped parameter mathematical model of the propellant supply pipeline includes: Establish the characteristic equation of fluid motion taking into account the fluid inertia factor; Establish the characteristic equation of fluid motion taking into account the local resistance factor of the fluid; Based on the fluid motion characteristic equation considering the fluid inertia factor and the fluid motion characteristic equation considering the fluid local resistance factor, a group of fluid flow characteristic equations considering both the fluid inertia factor and the fluid local resistance factor are obtained; The fluid motion characteristic equations in the fluid flow characteristic equation group that considers both the fluid inertia factor and the fluid local resistance factor are solved simultaneously to obtain a lumped parameter mathematical model of the propellant supply pipeline.

3. The method for simulating and determining the operating characteristics of a liquid rocket engine centrifugal pump-pipeline under variable load conditions according to claim 2, characterized in that: The expression of the characteristic equation of fluid motion considering the fluid inertia factor is: Wherein, G is the mass flow rate of the liquid in the flow path; t is the time; A is the minimum flow area at the local resistance; L is the length of the flow path segment; P1 is the inlet pressure of the flow path segment; P2 is the outlet pressure of the flow path segment; The expression of the fluid motion characteristic equation considering the local resistance factor of the fluid is: in, is the flow resistance coefficient when the valve is fully opened; μ is the flow coefficient; It is the product of μ and A when the valve is fully open.

4. The method for simulating and determining the operating characteristics of a liquid rocket engine centrifugal pump-pipeline under variable load conditions according to claim 3 is characterized in that: The fluid flow characteristic equations that consider both the fluid inertia factor and the fluid local resistance factor are as follows: P in -P1=R1·G 2 ; P4-P out =R3·G 2 ; Among them, P in is the fluid pressure before passing through the inlet local resistance; R1 is the first local resistance; L1 is the flow path segment length between the first fixed local resistance and the second adjustable local resistance; P3 is the fluid pressure after passing through the adjustable valve; is the second local resistance when the valve is fully opened; P4 is the fluid pressure before passing through the outlet local resistance; L2 is the flow path segment length between the second adjustable local resistance and the third fixed local resistance; P out is the fluid pressure after passing through the outlet local resistance; R3 is the third local resistance.

5. The method for simulating and determining the operating characteristics of a liquid rocket engine centrifugal pump-pipeline under variable load conditions according to claim 4, characterized in that: The expression of the lumped parameter mathematical model of the propellant supply pipeline is:

6. The method for simulating and determining the operating characteristics of a liquid rocket engine centrifugal pump-pipeline under variable load conditions according to claim 1, characterized in that: The process of establishing the centrifugal pump dynamic mathematical model specifically includes: Based on the actual connection relationship between the rotor and the inducer during the operation of the centrifugal pump, the mass flow transfer model between the inlet end face of the centrifugal pump and the outlet end face of the diffuser is determined; Based on the dynamic relationship of the supply liquid flowing through the centrifugal pump, a model for the change of the liquid pressure difference between the inlet and outlet of the centrifugal pump is determined; Based on the dynamic relationship of the supply liquid flowing through the centrifugal pump, a model for the change of the liquid temperature difference between the inlet and outlet of the centrifugal pump is determined.

7. The method for simulating and determining the operating characteristics of a liquid rocket engine centrifugal pump-pipeline under variable load conditions according to claim 6, characterized in that: The expression of the mass flow transfer model of the centrifugal pump inlet end face and the diffuser outlet end face is: in, is the inlet mass flow rate of the inducer; is the mass flow rate at the diffuser outlet; The expression of the centrifugal pump inlet and outlet liquid pressure difference change model is: P l2 =P l1 +ΔP l ; Among them, P l2 is the centrifugal pump outlet pressure; P l1 is the centrifugal pump inlet pressure; ΔP l is the dynamic pressure head of the centrifugal pump; ΔP s is the steady-state pressure head of the centrifugal pump; A m , A n is a constant related to the centrifugal pump structure and propellant density; is the liquid mass flow rate; n is the speed of the centrifugal pump; t is the time; The expression of the centrifugal pump inlet and outlet liquid temperature difference change model is: Where T is the liquid temperature; t i are the coefficients to be fitted, i∈[0,6]; p is the liquid pressure; ρ is the liquid density.

8. A system for simulating and determining the operating characteristics of a liquid rocket engine centrifugal pump-pipeline under variable load conditions, characterized in that: The liquid rocket engine centrifugal pump-pipeline operation characteristic simulation determination system under variable load conditions is used to implement the liquid rocket engine centrifugal pump-pipeline operation characteristic simulation determination method under variable load conditions according to claims 1-7, and the liquid rocket engine centrifugal pump-pipeline operation characteristic simulation determination system under variable load conditions includes: A model building unit is used to build a lumped parameter mathematical model of a propellant supply pipeline of a liquid rocket engine and a centrifugal pump dynamic mathematical model; the lumped parameter mathematical model of the propellant supply pipeline is built based on a fluid motion characteristic equation that takes into account a fluid inertia factor and a fluid motion characteristic equation that takes into account a fluid local resistance factor; the centrifugal pump dynamic mathematical model includes: a centrifugal pump inlet end face and a diffuser outlet end face mass flow transfer model, a centrifugal pump inlet and outlet liquid pressure difference change model, and a centrifugal pump inlet and outlet liquid temperature difference change model; A model building unit, used to build a corresponding propellant supply pipeline simulation model and a centrifugal pump simulation model in Simulink based on the lumped parameter mathematical model of the propellant supply pipeline and the centrifugal pump dynamics mathematical model respectively; A propellant supply pipeline operation characteristic determination unit is used to input different load condition parameters into the propellant supply pipeline simulation model to obtain the corresponding operation characteristics of the propellant supply pipeline under different load condition parameters; the load condition parameters include: liquid circuit fluid pressure, mass flow and temperature conditions; The centrifugal pump operation characteristic determination unit is used to input different load condition parameters into the centrifugal pump simulation model to obtain the corresponding operation characteristics of the centrifugal pump under different load condition parameters.

9. A computer device comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the method for simulating and determining the operating characteristics of a centrifugal pump-pipeline of a liquid rocket engine under variable load conditions as described in any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, it implements the method for simulating and determining the operating characteristics of a liquid rocket engine centrifugal pump-pipeline under variable load conditions described in any one of claims 1-7.

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