Rapid calculation method and system for flow field parameters of high-speed low-temperature hydrogen jet flow

Abstract

The invention discloses a rapid calculation method and system for high-speed low-temperature hydrogen jet flow field parameters. The method comprises the following steps that S1, a rapid calculation model for the high-speed low-temperature hydrogen jet flow field parameters is established; and S2, calculating low-temperature hydrogen jet flow field parameters based on the rapid calculation model. According to the method, parameters such as low-temperature hydrogen jet flow field concentration and temperature can be accurately and quickly calculated.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen safety, and in particular relates to a method and system for quickly calculating flow field parameters of a high-speed low-temperature hydrogen jet. Background Art

[0002] Hydrogen is a clean, efficient, ideal fuel and energy storage medium, but the volume energy density of hydrogen is very low, and conventional storage methods are difficult to meet the needs of large-scale storage and transportation. Cryogenic compressed hydrogen technology combines the advantages of high pressure and low temperature, and can achieve a very high energy storage density, so it has received more and more attention. However, due to the disadvantages of hydrogen such as easy leakage and low ignition energy, hydrogen safety issues have become the focus of public, enterprise and government. Especially for cryogenic hydrogen, leakage may cause serious accident consequences. In order to ensure the safety of cryogenic hydrogen use, the flow field characteristics of cryogenic hydrogen leakage jet must be fully studied. The existing hydrogen jet flow field calculation method mainly adopts numerical simulation based on computational fluid dynamics (CFD) and normal temperature Gaussian plume model. However, CFD simulation is time-consuming and has low computational efficiency. The normal temperature Gaussian plume model does not consider the condensation problem of air components caused by cryogenic hydrogen leakage and has poor calculation accuracy. Therefore, a more efficient and accurate method for calculating the flow field of cryogenic hydrogen jet is needed. Summary of the invention

[0003] In view of the problems of high cost, poor accuracy and low efficiency of existing low-temperature hydrogen jet flow field calculation methods, the present invention proposes a method and system for quickly calculating the flow field parameters of a high-speed low-temperature hydrogen jet, which can accurately and quickly calculate the concentration, temperature and other parameters of the low-temperature hydrogen jet flow field.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] A method for quickly calculating flow field parameters of a high-speed low-temperature hydrogen jet comprises the following steps:

[0006] S1: Establish a fast calculation model for the flow field parameters of high-speed low-temperature hydrogen jet;

[0007] S2: Calculate the low-temperature hydrogen jet flow field parameters based on the fast calculation model.

[0008] Preferably, the fast calculation model includes: a tank to true outlet model, an underexpansion zone model, an initial entrainment and heating zone model, a flow establishment zone model, and a fully developed zone model.

[0009] Preferably, the method for establishing the storage tank to real outlet model comprises:

[0010]

[0011] In the formula, is the mass flow rate from the tank to the actual outlet, V1 is the flow velocity at the actual outlet, which is equal to the local sound speed, ρ1 is the density of the actual outlet, which is obtained by calling the open source thermodynamic property calculation package COOLPROP, A1 is the cross-sectional area of ​​the actual outlet, and d is the nozzle diameter.

[0012] Preferably, the method for establishing the under-expansion zone model comprises:

[0013] ρ1V1A1=ρ2V2A2

[0014]

[0015] Where ρ2 is the density of the virtual nozzle outlet, which is obtained by calling the open source thermodynamic property calculation package COOLPROP, V2 is the flow rate at the virtual nozzle outlet, A2 is the virtual nozzle outlet area, P1 is the real outlet pressure, and P2 is the virtual nozzle outlet pressure, which is equal to the ambient pressure.

[0016] Preferably, the method for establishing the initial entrainment and heating zone model comprises:

[0017]

[0018]

[0019] In the formula, is the mass flow rate through the virtual nozzle outlet, h2 is the enthalpy value at the virtual nozzle outlet, is the flow rate leaving the initial entrainment and heating zone, i.e., state 3, and represents the flow rate of air at state 3 and the flow rate of liquid nitrogen produced by condensation, h3 is the enthalpy of the hydrogen-air mixture at state 3, V3 is the velocity of the hydrogen-air mixture at state 3, is the velocity of condensed nitrogen in state 3, h air is the enthalpy of air, is the enthalpy of liquid nitrogen, and r is the latent heat released due to condensation of nitrogen.

[0020] Preferably, the method for establishing the flow establishment zone model comprises:

[0021] B E =β B d3

[0022]

[0023] In the formula, B E is the characteristic jet width on the center line at the end of the flow development zone, β B =0.82 is the empirical constant, d3 is the diameter at the entrance of the flow establishment zone, Y cl,Eis the mass fraction on the center line of the end of the flow development zone, Y3 is the mass fraction at the entrance of the flow establishment zone, λ=1.16 is the ratio of the radial concentration diffusion rate and velocity diffusion rate of the jet gas, V cl,E is the velocity on the center line at the end of the flow development zone, ρ3 is the density at the entrance of the flow establishment zone, and ρ cl,E is the density on the centerline at the end of the flow development zone.

[0024] Preferably, the method for establishing the fully developed zone model comprises:

[0025] Establish the conservation equation of the integral type in the fully developed zone;

[0026] According to the conservation equation of the integral type in the fully developed zone, the system of integro-differential equations is established;

[0027] The length of the flow development zone S E and the density ρ on the centerline at the end of the flow development zone cl,E , center line speed Y cl,E and the initial jet characteristic width B E The jet centerline is discretized as the boundary condition of the integro-differential equations, and the fifth-order Runge-Kutta method is used to solve the integro-differential equations, and the fully developed zone model is established.

[0028] The present invention also provides a fast calculation system for high-speed low-temperature hydrogen jet flow field parameters, comprising: a model building module and a parameter calculation module;

[0029] The model building module is used to establish a fast calculation model for high-speed low-temperature hydrogen jet flow field parameters;

[0030] The parameter calculation module is used to calculate the low-temperature hydrogen jet flow field parameters based on the fast calculation model.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The present invention proposes a method and system for quickly calculating the flow field parameters of a low-temperature hydrogen jet, which can efficiently and accurately calculate the concentration, temperature and other parameters of the low-temperature hydrogen jet flow field.

[0033] The rapid calculation method and system of the rapid low-temperature hydrogen jet flow field parameters proposed in the present invention take into account the air condensation phenomenon of low-temperature hydrogen in the initial entrainment and heating sections, and more realistically restore the low-temperature hydrogen jet flow field.

[0034] The low-temperature hydrogen jet flow field parameter calculation model proposed in the present invention, which takes into account the initial entrainment of the jet and the condensation of air in the heating section, greatly improves the calculation efficiency while ensuring the accuracy of the calculation results. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0036] Figure 1 This is a flow chart of a method for quickly calculating flow field parameters of a high-speed low-temperature hydrogen jet according to an embodiment of the present invention;

[0037] Figure 2 A flow chart for establishing a model of a fast calculation method according to an embodiment of the present invention;

[0038] Figure 3 A flow field area division diagram of a fast calculation model according to an embodiment of the present invention;

[0039] Figure 4 A comparison chart of the jet concentration and temperature calculated by the method proposed in the embodiment of the present invention and the experimental measured values;

[0040] Figure 5 A comparison chart of the jet centerline concentration calculated by the method proposed in the embodiment of the present invention and the experimental measurement value;

[0041] Figure 6 A comparison chart of the jet centerline temperature calculated by the method proposed in the embodiment of the present invention and the experimental measurement value;

[0042] Figure 7 A comparison diagram of the jet concentration and temperature calculated by the method proposed in the embodiment of the present invention and the CFD simulation values;

[0043] Figure 8 A comparison diagram of the jet centerline concentration calculated by the method proposed in the embodiment of the present invention and the CFD simulation value;

[0044] Fig. 9 This is a comparison chart between the jet centerline temperature calculated by the method proposed in the embodiment of the present invention and the CFD simulation value. DETAILED DESCRIPTION

[0045] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0047] Embodiment 1

[0048] like Figure 1 and Figure 2 As shown, the present invention provides a method for quickly calculating the flow field parameters of a high-speed low-temperature hydrogen jet. When the input parameters are 3 bar, 51 K, and a diameter of 1.25 mm, by substituting the data of the input parameters into the model built in the method, the concentration, temperature and other parameters of the low-temperature hydrogen jet flow field are finally obtained. Specifically, the following steps are included:

[0049] S1 Rapid calculation model establishment.

[0050] S11 tank to real outlet model established.

[0051] The gas state in the tank and the nozzle geometry are known quantities, including the stagnation pressure (P0) and temperature (T0) in the tank, the nozzle diameter (d), etc.

[0052] The hydrogen mass flow rate per unit time through the nozzle cross section is used as the input condition to enter the model of the next area and can be calculated by the following formula:

[0053]

[0054] In the formula, is the mass flow rate from the storage tank to the actual outlet, V1 is the flow velocity at the actual outlet, which is equal to the local sound velocity, ρ1 is the density of the actual outlet, which is obtained by calling the open source thermodynamic property calculation package COOLPROP, and A1 is the cross-sectional area of ​​the actual outlet.

[0055] The S12 under-expansion zone model was established.

[0056] Since the high-pressure hydrogen jet is usually accompanied by a complex shock wave structure in the near field, the underexpanded jet needs to be simplified to a subsonic problem in order to provide equivalent boundary conditions for the overall integral model. The "virtual nozzle" model can be used for simplification. The parameters at the real outlet are used as input and substituted into the mass conservation and momentum conservation equations satisfied in this area:

[0057] ρ1V1A1=ρ2V2A2

[0058]

[0059] Where ρ2 is the density of the virtual nozzle outlet, which is obtained by calling the open source thermodynamic property calculation package COOLPROP, V2 is the flow rate at the virtual nozzle outlet, A2 is the virtual nozzle outlet area, P1 is the real outlet pressure, and P2 is the virtual nozzle outlet pressure, which is equal to the ambient pressure.

[0060] This region uses the parameters at the real outlet as input conditions, and then substitutes them into these conservation equations to obtain the parameters at the virtual nozzle outlet.

[0061] S13 initial entrainment and heating zone model is established.

[0062] When establishing the model for this region, the initial entrainment of nitrogen condensation is considered. Pure hydrogen (mass fraction Y = 1) from the underexpansion zone enters the initial entrainment and heating zone along the jet direction. The surrounding static ambient air is continuously entrained due to turbulence, and the formed hydrogen-air mixture leaves the initial entrainment and heating zone in the form of gas. Substitute the underexpansion zone outlet parameters as input conditions into the mass, momentum and energy conservation equations of this region:

[0063]

[0064]

[0065]

[0066] In the formula, is the mass flow rate through the virtual nozzle outlet, h2 is the enthalpy value at the virtual nozzle outlet, is the flow rate leaving the initial entrainment and heating zone (state 3), and represents the flow rate of air at state 3 and the flow rate of liquid nitrogen produced by condensation, h3 is the enthalpy of the hydrogen-air mixture at state 3, V3 is the velocity of the hydrogen-air mixture at state 3, is the velocity of condensed nitrogen in state 3, h air is the enthalpy of air, is the enthalpy of liquid nitrogen, and r is the latent heat released due to condensation of nitrogen.

[0067] In order to calculate the proportion of nitrogen condensation in the air in the jet, the condensation factor σ is introduced:

[0068]

[0069] Where T3 is the temperature of the hydrogen-air mixture in state 3, T condensation is the temperature at which nitrogen condenses, which is 77.35K, T solidification is the temperature at which nitrogen solidifies, which is 63.17K.

[0070] In this region, the parameters at the virtual nozzle outlet are used as input conditions, and then these conservation equations are substituted to obtain the parameters at the initial entrainment and heating zone outlets.

[0071] S14 flow establishment area model is established.

[0072] At this stage of jet development, its trajectory and behavior are affected not only by the initial momentum, but also by the buoyancy caused by the density difference between the gas and the surrounding medium. The assumptions used in the flow establishment zone are basically similar to those in the initial entrainment and heating zones, but the jet parameters of the cryogenic compressed hydrogen jet on the cross section in this region are no longer uniform, but gradually transition to a Gaussian distribution. In this region, the velocity, density, and concentration of the hydrogen-air mixture change with the change of the jet radius, and the jet parameters on the centerline decrease with the increase of the distance from the centerline of the jet.

[0073] In order to provide boundary conditions for the integral model in the fully developed zone in the next stage, it is necessary to determine the characteristic jet width (B) on the center line of the end of the flow development zone according to the parameters at state 3. E ), quality fraction (Y cl,E ) and speed (V cl,E ):

[0074] B E =β B d3

[0075]

[0076] In the formula, B E is the characteristic jet width on the center line at the end of the flow development zone, β B =0.82 is the empirical constant, d3 is the diameter at the entrance of the flow establishment zone, Y cl,E is the mass fraction on the center line of the end of the flow development zone, Y3 is the mass fraction at the entrance of the flow establishment zone, λ=1.16 is the ratio of the radial concentration diffusion rate and velocity diffusion rate of the jet gas, V cl,E is the velocity on the center line at the end of the flow development zone, ρ3 is the density at the entrance of the flow establishment zone, and ρ cl,E is the density on the centerline at the end of the flow development zone.

[0077] This area is the characteristic jet width (B) on the center line of the end of the flow development zone determined by the parameters at state 3. E ), quality fraction (Y cl,E ) and speed (V cl,E ) are directly used as the boundary conditions for solving the integral equation in the fully developed zone.

[0078] The S15 fully developed zone model was established.

[0079] The fully developed region is the longest region in the entire integral model. The flow parameters in this region satisfy the integral conservation equations, including the conservation equations of mass, momentum, hydrogen concentration, and energy:

[0080]

[0081] According to the above conservation equations, the integro-differential equations are established. Then, the length of the flow development zone (s E ) and the density on the center line at the end of this region (ρ cl,E ), centerline speed and (Y cl,E ) Initial jet characteristic width (B E ) is used as the boundary condition of the integral-differential equations, and the equations are discretized along the jet centerline. The fifth-order Runge-Kutta method is used to solve the equations, and the velocity, concentration, temperature and other parameters on the jet centerline are obtained, that is, the fully developed zone model is established.

[0082] Figure 3 This is a diagram of the rapid calculation model flow field area division, where numbers 1-5 represent the outlet thermodynamic states of the above four areas respectively.

[0083] S2 flow field parameter calculation.

[0084] On the basis of the above-mentioned rapid calculation model, the gas state in the tank and the nozzle geometry conditions are input into the model, including the stagnation pressure (P0) 3 bar, temperature (T0) 51 K, nozzle diameter (d) 1.25 mm and other parameters in the tank, and the concentration, temperature and other parameters of the low-temperature hydrogen jet flow field can be quickly calculated. The jet concentration and temperature calculated by the method proposed in the present invention are compared with the experimental measurement values. Figure 4 As shown in FIG. 1 , the jet centerline concentration calculated by the method proposed in the present invention is compared with the experimental measurement value. Figure 5 As shown in FIG. 1 , the jet centerline temperature calculated by the method proposed in the present invention is compared with the experimental measurement value. Figure 6 shown.

[0085] Implementation Case 2

[0086] In order to further verify the accuracy and applicability of the method proposed in the present invention, the calculation results of the fast calculation method of the method proposed in the present invention are also compared with the results of computational fluid dynamics numerical simulation. When the input parameters are 3 bar, 51 K, and the diameter is 1.25 mm, the parameters such as the concentration and temperature of the low-temperature hydrogen jet flow field are finally obtained by substituting the data of the input parameters into the model built in the method, which specifically includes the following steps:

[0087] S1 Rapid calculation model establishment.

[0088] S11 tank to real outlet model established.

[0089] The gas state in the tank and the nozzle geometry are known quantities, including the stagnation pressure (P0) and temperature (T0) in the tank, the nozzle diameter (d), etc.

[0090] The hydrogen mass flow rate per unit time through the nozzle cross section is substituted into the model of the next area as an input condition and can be calculated by the following formula:

[0091]

[0092] In the formula, is the mass flow rate from the storage tank to the actual outlet, V1 is the flow velocity at the actual outlet, which is equal to the local sound velocity, ρ1 is the density of the actual outlet, which is obtained by calling the open source thermodynamic property calculation package COOLPROP, and A1 is the cross-sectional area of ​​the actual outlet.

[0093] The S12 under-expansion zone model was established.

[0094] Since the high-pressure hydrogen jet is usually accompanied by a complex shock wave structure in the near field, the underexpanded jet needs to be simplified to a subsonic problem in order to provide equivalent boundary conditions for the overall integral model. The "virtual nozzle" model can be used for simplification. The mass conservation and momentum conservation equations satisfied in this region are as follows:

[0095] ρ1V1A1=ρ2V2A2

[0096]

[0097] Where ρ2 is the density of the virtual nozzle outlet, which is obtained by calling the open source thermodynamic property calculation package COOLPROP, V2 is the flow rate at the virtual nozzle outlet, A2 is the virtual nozzle outlet area, P1 is the real outlet pressure, and P2 is the virtual nozzle outlet pressure, which is equal to the ambient pressure.

[0098] S13 initial entrainment and heating zone model is established.

[0099] When the model is established in this area, the initial entrainment of nitrogen condensation is considered. Pure hydrogen (mass fraction Y = 1) from the underexpansion zone enters the initial entrainment and heating zone along the jet direction. The surrounding static ambient air is continuously entrained due to turbulence, and the formed hydrogen-air mixture leaves the initial entrainment and heating zone in the form of gas. The mass, momentum and energy conservation equations of this area are as follows:

[0100]

[0101]

[0102] In the formula, is the mass flow rate through the virtual nozzle outlet, h2 is the enthalpy value at the virtual nozzle outlet, is the flow rate leaving the initial entrainment and heating zone (state 3), and represents the flow rate of air at state 3 and the flow rate of liquid nitrogen produced by condensation, h3 is the enthalpy of the hydrogen-air mixture at state 3, V3 is the velocity of the hydrogen-air mixture at state 3, is the velocity of condensed nitrogen in state 3, h air is the enthalpy of air, is the enthalpy of liquid nitrogen, and r is the latent heat released due to condensation of nitrogen.

[0103] In order to calculate the proportion of nitrogen condensation in the air in the jet, the condensation factor σ is introduced:

[0104]

[0105] The subscript “condensation” here means condensation, and “solidification” means solidification.

[0106] S14 flow establishment area model is established.

[0107] At this stage of jet development, its trajectory and behavior are affected not only by the initial momentum, but also by the buoyancy caused by the density difference between the gas and the surrounding medium. The assumptions used in the flow establishment zone are basically similar to those in the initial entrainment and heating zones, but the jet parameters of the cryogenic compressed hydrogen jet on the cross section in this region are no longer uniform, but gradually transition to a Gaussian distribution. In this region, the velocity, density, and concentration of the hydrogen-air mixture change with the change of the jet radius, and the jet parameters on the centerline decrease with the increase of the distance from the centerline of the jet.

[0108] In order to provide boundary conditions for the next stage of the integral model in the fully developed region, it is necessary to determine the characteristic jet width (B E ), quality fraction (Y cl,E ) and speed (V cl,E ):

[0109] B E =β B d3

[0110]

[0111] In the formula, B E is the characteristic jet width on the center line at the end of the flow development zone, β B =0.82 is the empirical constant, d3 is the diameter at the entrance of the flow establishment zone, Y cl,E is the mass fraction on the center line of the end of the flow development zone, Y3 is the mass fraction at the entrance of the flow establishment zone, λ=1.16 is the ratio of the radial concentration diffusion rate and velocity diffusion rate of the jet gas, V cl,Eis the velocity on the center line at the end of the flow development zone, ρ3 is the density at the entrance of the flow establishment zone, and ρ cl,E is the density on the centerline at the end of the flow development zone.

[0112] The S15 fully developed zone model was established.

[0113] The fully developed zone is the longest region in the entire integral model. The flow parameters in this region satisfy the integral conservation equations, including the conservation equations of mass, momentum, hydrogen concentration and energy. Based on the above conservation equations, an integral-differential equation system is established. Then, the length of the flow development zone (s E ) and the density on the center line at the end of this region (ρ cl,E ), centerline speed and (Y cl,E ) Initial jet characteristic width (B E ) is used as the boundary condition of the integro-differential equations, which are discretized along the jet centerline and solved using the fifth-order Runge-Kutta method.

[0114] S2 flow field parameter calculation.

[0115] On the basis of the above-mentioned rapid calculation model, the gas state in the tank and the nozzle geometry conditions are input into the model, including the stagnation pressure (P0) 3 bar, temperature (T0) 51 K, nozzle diameter (d) 1.25 mm and other parameters in the tank, so that the concentration, temperature and other parameters of the low-temperature hydrogen jet flow field can be quickly calculated. The jet concentration and temperature calculated by the method proposed in the present invention are compared with the CFD simulation values. Figure 7 As shown in FIG. 1 , the jet centerline concentration calculated by the method proposed in the present invention is compared with the CFD simulation value. Figure 8 As shown in FIG. 1 , the jet centerline temperature calculated by the method proposed in the present invention is compared with the CFD simulation value. Fig. 9 shown.

[0116] Embodiment 3

[0117] The present invention also provides a fast calculation system for high-speed low-temperature hydrogen jet flow field parameters, comprising: a model building module and a parameter calculation module;

[0118] The model building module is used to establish a fast calculation model for the flow field parameters of high-speed low-temperature hydrogen jets;

[0119] The parameter calculation module is used to calculate the low-temperature hydrogen jet flow field parameters based on the fast calculation model.

[0120] The embodiments described above are only descriptions of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for rapid calculation of flow field parameters of high-speed low-temperature hydrogen jet, characterized in that: The following steps are involved: S1: Establish a fast calculation model for the flow field parameters of high-speed low-temperature hydrogen jet; S2: Calculating the low-temperature hydrogen jet flow field parameters based on the fast calculation model.

2. The rapid calculation method of high-speed low-temperature hydrogen jet flow field parameters according to claim 1 is characterized in that: The fast calculation model includes: a tank to real outlet model, an underexpansion zone model, an initial entrainment and heating zone model, a flow establishment zone model, and a fully developed zone model.

3. The rapid calculation method of high-speed low-temperature hydrogen jet flow field parameters according to claim 2 is characterized in that: The method for establishing the storage tank to real outlet model includes: Where, is the mass flow rate from the tank to the actual outlet, V1 is the flow velocity at the actual outlet, which is equal to the local sound speed, ρ1 is the density of the actual outlet, which is obtained by calling the open source thermodynamic property calculation package COOLPROP, A1 is the cross-sectional area of ​​the actual outlet, and d is the nozzle diameter.

4. The method for rapidly calculating flow field parameters of a high-speed, low-temperature hydrogen jet according to claim 3, characterized in that: The method for establishing the under-expansion zone model comprises: ρ1V1A1=ρ2V2A2 Where ρ2 is the density at the virtual nozzle outlet, which is obtained by calling the open source thermodynamic property calculation package COOLPROP, V2 is the flow velocity at the virtual nozzle outlet, A2 is the area of ​​the virtual nozzle outlet, P1 is the pressure of the real outlet, and P2 is the pressure at the virtual nozzle outlet, which is equal to the ambient pressure.

5. The method for rapidly calculating flow field parameters of a high-speed, low-temperature hydrogen jet according to claim 4, characterized in that: The method for establishing the initial entrainment and heating zone model includes: Where, is the mass flow rate through the virtual nozzle outlet, h2 is the enthalpy value at the virtual nozzle outlet, is the flow rate leaving the initial entrainment and heating zone, i.e., state 3, and represents the flow rate of air at state 3 and the flow rate of liquid nitrogen produced by condensation, h3 is the enthalpy of the hydrogen-air mixture at state 3, V3 is the velocity of the hydrogen-air mixture at state 3, is the velocity of condensed nitrogen in state 3, h air is the enthalpy of air, is the enthalpy of liquid nitrogen, and r is the latent heat released due to condensation of nitrogen.

6. The method for rapidly calculating flow field parameters of a high-speed, low-temperature hydrogen jet according to claim 5, characterized in that: The method for establishing the flow establishment area model includes: B E =β B d3 Where B E is the characteristic jet width at the center line of the end of the flow development zone, β B =0.82 is the empirical constant, d3 is the diameter at the entrance of the flow establishment area, Y cl,E is the mass fraction on the center line of the end of the flow development zone, Y3 is the mass fraction at the entrance of the flow establishment zone, λ = 1.16 is the ratio of the radial concentration diffusivity and velocity diffusivity of the jet gas, V cl,E is the velocity at the center line of the end of the flow development zone, ρ3 is the density at the entrance of the flow establishment zone, and ρ cl,E is the density at the center line of the end of the flow development zone.

7. The method for rapidly calculating flow field parameters of a high-speed, low-temperature hydrogen jet according to claim 6, characterized in that: The method for establishing the fully developed zone model includes: Establish the integral type conservation equation for the fully developed zone; According to the integral type conservation equation of the fully developed region, the system of integral-differential equations is established; The length of the flow development zone S E and the density ρ on the centerline at the end of the flow development zone cl,E , center line speed Y cl,E and the initial jet characteristic width B E The jet centerline is discretized as the boundary condition of the integro-differential equations, and the fifth-order Runge-Kutta method is used to solve the integro-differential equations, and the fully developed zone model is established.

8. A fast calculation system for high-speed low-temperature hydrogen jet flow field parameters, characterized in that: include: Model building module and parameter calculation module; The model building module is used to establish a fast calculation model for high-speed low-temperature hydrogen jet flow field parameters; The parameter calculation module is used to calculate the low-temperature hydrogen jet flow field parameters based on the fast calculation model.

Images