CN111475939A - Simulation calculation method for ballistic performance of gas jet impacting liquid water column - Google Patents
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Abstract
The invention discloses a simulation calculation method for ballistic performance of gas jet impacting liquid water column, comprising the following steps: presetting a simulation calculation model precondition; establishing a gas-liquid physical action process model based on the precondition of the step S1; the whole internal trajectory process is divided into four simulation calculation stages based on a gas-liquid physical action process model, wherein the four simulation calculation stages are respectively as follows: the method comprises a gas generation flow calculation stage, a gas inflow state calculation stage, a liquid column movement calculation stage and a high-low pressure chamber pressure calculation stage; and acquiring a pressure curve of the high-pressure chamber and the low-pressure chamber. The method can realize the simple and high-efficiency acquisition of the inner ballistic performance parameters and the thrust characteristics of the liquid column balance body phenomenon in the gas jet impact pipe, and has important significance for the research of the structure optimization design of industrial products, military equipment and other systems with the liquid column balance body phenomenon in the gas jet impact pipe.
Description
Technical Field
The invention relates to the field of industrial production and military, in particular to a simulation calculation method for ballistic performance of gas jet impacting liquid water column.
Background
The theoretical research and test system of the gas jet impact liquid column balancing body comprises an ignition system, a gas generation system, a spray pipe, a cylindrical pipe and other components, wherein the injection process takes ignition of ignition powder as a starting point, the pressure in a combustion chamber is reduced to the atmospheric pressure after all gas and liquid are sprayed out of the cylindrical pipe as an end point, and the process of complex and changing processes of ignition powder ignition, propellant combustion, spray pipe film breaking, gunpowder gas flowing, and the like are jointly sprayed out of the cylindrical pipe in a strong interaction process after the liquid column is impacted.
Although some internal ballistic parameters can be obtained accurately through experimental research, a lot of time and energy are consumed, and uncertain errors are brought to experimental data acquisition along with unstable professional qualities of experimenters. Therefore, in recent years, the physical action process is simulated based on fluid simulation calculation, so that the inner ballistic trajectory parameter is calculated through simulation, but because the change of the gas jet impacting the liquid column balance body form has randomness, a physical hypothesis change model which is close to the actual physical action process and deformation and is beneficial to simulation calculation needs to be selected, and the simulation calculation can be reasonable and effective.
Disclosure of Invention
The purpose of the invention is as follows: in order to overcome the defects in the prior art, the method for simulating and calculating the ballistic performance of the gas jet impacting liquid water column is provided, the change condition of each internal ballistic parameter in the launching process can be accurately and effectively obtained, the test times are reduced, the test cost is saved, the method can be widely applied to theoretical research and verification simulation related to the liquid balance launching process in large-scale equipment manufacturing and military equipment manufacturing, and a theoretical basis is provided for the structural design of manufacturing equipment adopting a liquid balance launching mode and the design of the internal ballistic process.
The technical scheme is as follows: in order to achieve the purpose, the invention provides a simulation calculation method for ballistic performance of gas jet impacting liquid water column, which comprises the following steps:
s1: presetting a simulation calculation model precondition;
s2: establishing a gas-liquid physical action process model based on the precondition of the step S1;
s3: the whole internal trajectory process is divided into four simulation calculation stages based on a gas-liquid physical action process model, wherein the four simulation calculation stages are respectively as follows: the method comprises a gas generation flow calculation stage, a gas inflow state calculation stage, a liquid column movement calculation stage and a high-low pressure chamber pressure calculation stage;
s3: and acquiring a pressure curve of the high-pressure chamber and the low-pressure chamber.
Further, the simulation calculation model precondition in the step S1 includes five conditions of a gunpowder combustion condition, a gas generation condition, a gas flow mode, an average pressure model, and a secondary work processing method.
Further, the gas-liquid physical action process model in the step S2 is divided into four stages, i.e., no gas-liquid contact, initial gas-liquid impact, propulsion under gas-liquid action, and no liquid in the cylindrical tube.
Further, the step of calculating the gas generation flow rate in step S3 is as follows:
step S3.1-1: calculating the gas generation in the combustion chamber
The combustion rate equation of the propellant:
propellant shape function:
wherein Z is the burned thickness percentage, t is the time, u1Is a combustion rate coefficient, p is an average pressure in the combustion chamber, n is a combustion rate index, e1Half of the initial arc thickness of the propellant, ZkThe relative thickness of the particles is burned off when the particles are completely burned off after the propellant is split, if dsIs the radius of the inscribed circle of the section of the crumb, Zk＝(e1+ds)/e1Phi is the burned mass percentage of gunpowder, chi, lambda and mu are the characteristic quantity of propellant shapes、λsIs the shape characteristic quantity of the propellant at the splitting moment;
gas state equation in the combustion chamber:
wherein f is propellant powder, omega is propellant mass, and tau is T/TzIn a combustion chamberη is the relative outflow of gas into the cylindrical tube in the combustion chamber, f1As the ignition powder or powder, omega1For ignition charge quality, V0Is the combustion chamber volume, ρpα is the residual volume of gas generated by the combustion of propellant, α for propellant density1The residual capacity of gas generated by the ignition powder combustion;
energy equation within the combustor system:
in the formula knThe specific heat ratio of fuel gas is generated for the combustion of the propellant;
step S3.1-2: calculating the gas outflow of the nozzle of the combustion chamber
Relative outflow equation of gas outflow in the combustion chamber:
in the formula
Is the flow loss coefficient, StIs the area of the nozzle throat, pbIs the average pressure inside the cylindrical tube. Ideally, all the gas sprayed from the nozzle of the combustion chamber is sprayed into the cylindrical pipe orifice without loss.
Further, the calculation step of the gas flowing state into the cylindrical pipe in the step S3 is as follows:
step S3.2-1: calculating the state in the gas pipe
Equation of state of gas in the cylindrical tube:
in the formula tau1＝T1/TzThe ratio of the absolute temperature in the cylindrical tube to the combustion explosion temperature of the propellant, η1Is round after the liquid water column is completely sprayed out of the cylindrical pipeThe relative outflow of the fuel gas from the column into the ambient atmosphere,
for the calculation of the coefficient of secondary work, m is the mass of the liquid water column, V is the speed of movement of the liquid water column, VψIs the initial free volume, V, between the nozzle outlet and the liquid column in the cylindrical tube1Increase in free volume caused by gas impacting the liquid column;
energy equation in cylindrical tube system:
step S3.2-2: calculating the internal flow of a gas pipe
Relative outflow equation of gas flowing out in the cylindrical pipe:
in the formula SdIs the cross-sectional area of the outlet of the cylindrical pipe, PaIs the ambient atmospheric pressure.
Further, the calculation process of the liquid column movement in the cylindrical tube in step S3 is as follows:
equation of motion of the liquid column:
wherein l is the movement displacement of the liquid column, PfFor damping the movement of the fluid column, SnIs the effective thrust area of the gas to the liquid column,
the liquid column mass correction coefficient is obtained;
equation of change of cavity volume:
wherein r' is the vertical distance from the top of the cavity to the inner orifice, and r is the radius of the inner pipe.
Further, in step S3, the internal ballistic equation set is used to calculate the high-low pressure chamber pressure.
Further, in the step S3, a fourth-order longge-kuta method is adopted to solve the internal trajectory equation set in the process of the gas jet impinging on the liquid column, and the specific calculation method is as follows:
for a first order system of differential equations:
when the variable i is set to 1,2, …, n, the initial value of the differential equation set is yi(t)＝yi0Further, the formula of the fourth order Runge-Kutta method can be written as:
at the right end of the formula h ═ tk+1-tkFor the time step, the assignment formula of each order variable in brackets is as follows:
and (3) gradually iterating by the fourth-order Runge-Kutta method to obtain a numerical solution of a first-order differential equation set formula (12), taking time t as an independent variable for an internal trajectory equation set of the gas jet impact liquid column balancing body, integrating a time step by calling the fourth-order Runge-Kutta method after each variable is endowed with an initial value, and repeating gradual integration to obtain a final calculation result. The calculation result is the data of the powder burning percentage, the high pressure chamber pressure, the low pressure chamber pressure, the liquid column movement length, the liquid column movement speed and the like at the time point after each time step is added, and finally the obtained data is subjected to drawing to obtain the curve of the change of each parameter, particularly the high pressure chamber pressure and the low pressure chamber pressure along with the time in the whole process of the gas jet acting on the liquid column.
The method of the invention provides a new ideal deformation hypothesis model for the shape deformation process of the liquid column after the jet impact in the physical action process of the gas jet impacting the liquid column in the cylindrical pipe. Namely, after the jet flow impacts the liquid column in the pipe, the liquid column is in a cavity, the cavity is in an ellipsoid shape from the early stage, the cavity is in a hemisphere shape with the head part, the rear part is connected into a cylinder with the same diameter and develops in the liquid water column, the liquid water column continuously moves out of the cylindrical pipe under the pushing of the gas jet flow, and when one end of the liquid water column close to the outlet of the spray pipe moves for a distance equal to the length of the cylindrical pipe, the liquid is supposed to be completely sprayed out of the cylindrical pipe. Meanwhile, the liquid column quality is kept unchanged, assuming that there is no liquid water vaporization during the physical action.
Has the advantages that: compared with the prior art, the invention has the following advantages:
1. compared with the method for assuming the liquid column balancing body as a solid-like balancing body with a constant shape, the physical assumption model designed by the method is closer to the practical engineering application condition, and the result obtained by calculation is more consistent with the test result, so that the simulation calculation precision is improved, and the method has important significance for researching the structure optimization design of industrial products, military equipment and other systems with the phenomenon that the gas jet impacts the liquid column balancing body in the pipe.
2. The change condition of each internal ballistic parameter in the launching process can be accurately and effectively acquired, the test times are reduced, and the test cost is saved.
Drawings
FIG. 1 is a schematic diagram of the movement of a liquid water column and the variation process of a cavity, wherein (a) is a liquid water column structure at the early stage of impact and (b) is a liquid water column structure at the late stage of impact;
FIG. 2 is a schematic diagram of a process of generating theoretical assumptions about a hemisphere by impacting a liquid column cavity with a gas;
FIG. 3 is a graph showing a simulation curve of the pressure in the high pressure chamber and a comparison of the experimentally obtained curve.
Detailed Description
The invention is further elucidated with reference to the drawings and the embodiments.
The liquid column balance in the gas jet impact cylindrical pipe is a common application scene in the fields of industrial production and military, and in order to obtain a better impact effect, the impact action process mechanism needs to be deeply researched, various internal ballistic parameters in the action process are obtained, so as to guide the research and analysis of the physical process principle of the gas jet, and further guide the optimization design process of the structure and the performance of each related material of the gas jet.
The invention provides a simulation calculation method for ballistic performance of gas jet impacting liquid water column, comprising the following steps:
s1: presetting simulation calculation model preconditions:
gunpowder combustion conditions: assuming that the powder for generating the fuel gas is completely combusted, and the propellant is instantly and completely ignited, the combustion process of the propellant follows a geometric combustion law, and the combustion speed is in an exponential function relation with the average pressure in the fuel gas generation chamber.
Gas generation conditions: assuming that the composition of gunpowder gas generated by propellant combustion is unchanged and obeys the Nobel-Abel equation of state, relevant parameters such as the explosive power f and the gas adiabatic index k ═ Cp/CVThe residual capacity α and the like are constants;
gas flow mode: supposing that after the pressure in the combustion chamber reaches the membrane breaking pressure, the pressure limiting membrane at the spray pipe is instantaneously sheared, gunpowder gas quickly flows out of the spray pipe without considering the shearing process, and the process that the gunpowder gas flows into the cylindrical pipe through the spray pipe is regarded as isentropic flow.
Mean pressure model: it is assumed that the combustion of the propellant in the combustion chamber and the intermixing flow process of the gas and liquid are carried out under mean pressure conditions.
The secondary work processing method comprises the following steps: and (3) assuming that various forms of secondary work such as heat loss, gunpowder gas flow, frictional resistance work and the like are corrected by adopting secondary work calculation coefficients.
S2: establishing a gas-liquid physical action process model based on the precondition of the step S1, wherein the gas-liquid physical action process model is divided into four stages of no gas-liquid contact, initial gas-liquid impact, propulsion under the gas-liquid action and no liquid in the cylindrical pipe, and the mass of the model is assumed to be unchanged under the gas impact vaporization action of the liquid, and the four stages are described as follows:
gas-liquid non-contact stage (t ═ 0-0.3 ms): it can be known from the general numerical simulation of the process of impacting the liquid water column by the gas jet, that in the time period of t being 0-0.3ms, the gas-liquid interface does not change obviously, the cavity is not formed yet, but the gas flows out from the combustion chamber at the moment, so that in the stage of 0-0.3ms, no gas flows into the cylindrical pipe, and the gas and the liquid column in the pipe are ideally contactless.
Initial stage of gas-liquid impact (t is 0.3-0.8 ms): when the gas jet impacts the liquid column in the cylindrical pipe, an obvious cavity is formed, according to general numerical simulation experience, the early cavity of the impact is in an ellipsoid shape under the assumption that the gas starts to contact and impact the liquid column in the pipe from 0.3ms, and the volume of the ellipsoid-shaped cavity is determined by the displacement of a gas-liquid interface along with the development of time and the fact that the diameter of a circle at the bottom of the cavity is equal to the diameter of an outlet of the spray pipe. Assuming that t is 0.8ms, the cavity appears hemispherical when the gas-liquid interface has the same length as the nozzle exit radius. At this stage, the gas jet has begun to push the liquid water column out of the cylindrical tube.
A gas-liquid action propulsion stage: after the cavity is hemispherical, a cylindrical space with the same pipe diameter is formed behind the cavity and is continuously connected with the cavity at the hemispherical head part in the liquid water column for growth and development, the liquid water column continuously moves out of the cylindrical pipe under the pushing of the fuel gas jet, and the volume of the cavity at the head part hemispherical body is assumed to be unchanged in the period. When the end of the liquid jet near the nozzle outlet moves a distance equal to the length of the cylindrical tube, it is assumed that the liquid has been completely ejected from the cylindrical tube.
No liquid stage in the cylindrical tube: in this phase, the liquid water column has been pushed out of the cylindrical pipe by the gas jet, which flows out of the nozzle through the cylindrical pipe and into the external atmosphere, the cylindrical pipe corresponding to the low pressure chamber, the specific process of which is shown in fig. 1.
S3: mathematical model construction
The whole internal trajectory process is divided into four simulation calculation stages based on a gas-liquid physical action process model, wherein the four simulation calculation stages are respectively as follows: the method comprises a gas generation flow calculation stage, a gas inflow state calculation stage, a liquid column movement calculation stage and a high-low pressure chamber pressure calculation stage, wherein the gas generation flow calculation stage comprises the following steps:
1) and calculating the gas outflow in the combustion chamber to obtain the high-speed gas flow impacting the liquid column in the pipe, wherein the calculation steps of the gas generation flow are as follows:
1.1) calculating the gas generation in the combustion chamber
The combustion rate equation of the propellant:
propellant shape function:
wherein Z is the burned thickness percentage, t is the time, u1Is a combustion rate coefficient, p is an average pressure in the combustion chamber, n is a combustion rate index, e1Half of the initial arc thickness of the propellant, ZkThe relative thickness of the particles is burned off when the particles are completely burned off after the propellant is split, if dsIs the radius of the inscribed circle of the section of the crumb, Zk＝(e1+ds)/e1Phi is the burned mass percentage of gunpowder, chi, lambda and mu are the characteristic quantity of propellant shapes、λsIs the shape characteristic quantity of the propellant at the splitting moment;
gas state equation in the combustion chamber:
wherein f is propellant powder, omega is propellant mass, and tau is T/TzIs a combustion chamberThe ratio of the absolute temperature of the inner part to the combustion explosion temperature of the propellant, η is the relative outflow rate of the fuel gas in the combustion chamber into the cylindrical pipe, f1As the ignition powder or powder, omega1For ignition charge quality, V0Is the combustion chamber volume, ρpα is the residual volume of gas generated by the combustion of propellant, α for propellant density1The residual capacity of gas generated by the ignition powder combustion;
energy equation within the combustor system:
in the formula knThe specific heat ratio of fuel gas is generated for the combustion of the propellant;
1.2) calculating the gas outflow of the nozzle of the combustion chamber
Relative outflow equation of gas outflow in the combustion chamber:
in the formula
Is the flow loss coefficient, StIs the area of the nozzle throat, pbIs the average pressure inside the cylindrical tube. Ideally, all the gas sprayed from the nozzle of the combustion chamber is sprayed into the cylindrical pipe orifice without loss.
2) The method comprises the following steps of calculating the gas state in the pipe from the moment that a pressure limiting diaphragm at the throat is broken to the moment that liquid flows out of the cylindrical pipe completely, wherein the period is the most complicated period in the whole internal ballistic process and comprises the combustion of a propellant, a mathematical simulation model structure of the phenomena that the liquid water column is completely pushed out of the internal pipe, the pressure in a combustion chamber is balanced with the atmospheric pressure instantly, and the like, wherein the calculation steps of the gas state flowing into the cylindrical pipe are as follows:
2.1) calculating the conditions in the gas pipe
Equation of state of gas in the cylindrical tube:
in the formula tau1＝T1/TzThe ratio of the absolute temperature in the cylindrical tube to the combustion explosion temperature of the propellant, η1The relative outflow quantity of the fuel gas in the cylindrical pipe flowing into the external atmosphere environment after the liquid water column is totally sprayed out of the cylindrical pipe,
for the calculation of the coefficient of secondary work, m is the mass of the liquid water column, V is the speed of movement of the liquid water column, VψIs the initial free volume, V, between the nozzle outlet and the liquid column in the cylindrical tube1Increase in free volume caused by gas impacting the liquid column;
energy equation in cylindrical tube system:
2.2) calculating the outflow rate in the gas pipe
Relative outflow equation of gas flowing out in the cylindrical pipe:
where Sd is the cross-sectional area of the outlet of the cylindrical pipe, PaIs the ambient atmospheric pressure.
3) Calculating the pushing process of the gas acting on the liquid water column in the inner pipe, wherein the pushing process comprises the formation of a gas cavity in the liquid water column, the movement of the liquid water column pushed by gas expansion and the like, the theoretical assumption of the formation process of the liquid column cavity is as shown in figure 2, wherein P is gas pressure, a is the radius of the bottom of the cavity, and the calculation process of the movement of the liquid column in the cylindrical pipe is as follows:
equation of motion of the liquid column:
wherein l is the movement displacement of the liquid column, PfFor damping the movement of the fluid column, SnIs the effective thrust area of the gas to the liquid column,
the liquid column mass correction coefficient is obtained;
equation of change of cavity volume:
wherein r' is the vertical distance from the top of the cavity to the inner orifice, and r is the radius of the inner pipe.
4) Calculating pressure of high-pressure chamber and low-pressure chamber based on classical internal trajectory model
The internal ballistic equation system is formed by combining an ordinary differential equation system and an algebraic equation, and before a computer appears, the traditional solution method comprises the following steps: empirical methods, analytical methods, mathematical methods and graphical methods, which are simple and intuitive, but have great limitations. In this embodiment, a fourth-order longge-kuta method is adopted to solve an internal trajectory equation set in a process of a gas jet impacting a liquid column, and a fourth-order longge-kuta calculation method with a fixed step length is as follows:
for a first order system of differential equations:
assuming that the variable i is 1,2, …, n, the initial value of the differential equation set is yi(t)＝yi0Further, the formula of the fourth order Runge-Kutta method can be written as:
at the right end of the formula h ═ tk+1-tkFor the time step, the assignment formula of each order variable in brackets is as follows:
the numerical solution of first order differential equation set (12) can be obtained by stepwise iteration through the fourth order Runge-Kutta method described above. For the internal ballistic equation set of the gas jet impacting liquid column balancing body, if time t is used as an independent variable, after each variable is given an initial value, a fourth-order Runge-Kutta method is called to integrate a time step, and the final calculation result can be obtained by repeating the gradual integration. The calculation result is the data of the powder burning percentage, the high pressure chamber pressure, the low pressure chamber pressure, the liquid column movement length, the liquid column movement speed and the like at the time point after each time step is added.
5) The obtained data can be used for obtaining curves of various parameters, particularly the pressure of the high-pressure chamber and the pressure of the low-pressure chamber, changing along with time in the whole process of the gas jet acting on the liquid column through mapping.
In this embodiment, through the assumption of the physical process and the establishment of the mathematical model, the mathematical model can be implemented by programming, a pressure simulation curve of the high-pressure chamber is obtained by calculation, and the simulation curve is compared with an experimentally obtained curve, specifically, as shown in fig. 3, the shape of the pressure curve is close to that of the experimentally obtained curve in time variation, so that it is verified that the simulation calculation method used in this embodiment has good simulation accuracy.
Claims (8)
1. A simulation calculation method for ballistic performance of gas jet impact liquid water column is characterized by comprising the following steps:
s1: presetting a simulation calculation model precondition;
s2: establishing a gas-liquid physical action process model based on the precondition of the step S1;
s3: the whole internal trajectory process is divided into four simulation calculation stages based on a gas-liquid physical action process model, wherein the four simulation calculation stages are respectively as follows: the method comprises a gas generation flow calculation stage, a gas inflow state calculation stage, a liquid column movement calculation stage and a high-low pressure chamber pressure calculation stage;
s3: and acquiring a pressure curve of the high-pressure chamber and the low-pressure chamber.
2. The method for calculating the simulation of the ballistic performance of a gas jet impinging on a liquid water column as claimed in claim 1, wherein the precondition of the simulation calculation model in the step S1 includes five conditions of gunpowder combustion condition, gas generation condition, gas flow mode, mean pressure model and secondary function processing method.
3. The method for simulating and calculating the ballistic performance of the gas jet impinging liquid water column according to claim 1, wherein the gas-liquid physical action process model in step S2 is divided into four stages, namely, no gas-liquid contact, initial gas-liquid impact, propulsion by gas-liquid action and no liquid in the cylindrical pipe.
4. The method for simulating and calculating the ballistic performance of the gas jet impinging on the liquid water column according to claim 1, wherein the step of calculating the gas generation flow rate in the step S3 is as follows:
step S3.1-1: calculating the gas generation in the combustion chamber
The combustion rate equation of the propellant:
propellant shape function:
wherein Z is the burned thickness percentage, t is the time, u1Is a combustion rate coefficient, p is an average pressure in the combustion chamber, n is a combustion rate index, e1Half of the initial arc thickness of the propellant, ZkThe relative thickness of the particles is burned off when the particles are completely burned off after the propellant is split, if dsIs the radius of the inscribed circle of the section of the crumb, Zk＝(e1+ds)/e1Phi is the burned mass percentage of gunpowder, chi, lambda and mu are the characteristic quantity of propellant shapes、λsIs the shape characteristic quantity of the propellant at the splitting moment;
gas state equation in the combustion chamber:
wherein f is propellant powder, omega is propellant mass, and tau is T/TzIs the ratio of absolute temperature in the combustion chamber to the combustion explosion temperature of the propellant, η is the relative outflow of gas into the cylindrical tube in the combustion chamber, f1As the ignition powder or powder, omega1For ignition charge quality, V0Is the combustion chamber volume, ρpα is the residual volume of gas generated by the combustion of propellant, α for propellant density1The residual capacity of gas generated by the ignition powder combustion;
energy equation within the combustor system:
in the formula knThe specific heat ratio of fuel gas is generated for the combustion of the propellant;
step S3.1-2: calculating the gas outflow of the nozzle of the combustion chamber
Relative outflow equation of gas outflow in the combustion chamber:
in the formula
Is the flow loss coefficient, StPb is the average pressure in the cylindrical tube, the nozzle throat area. Ideally, all the gas sprayed from the nozzle of the combustion chamber is sprayed into the cylindrical pipe orifice without loss.
5. The method for calculating the simulation of the ballistic performance of the gas jet impinging on the liquid water column according to claim 1, wherein the calculation of the gas flowing into the cylindrical pipe in step S3 comprises the following steps:
step S3.2-1: calculating the state in the gas pipe
Equation of state of gas in the cylindrical tube:
in the formula tau1＝T1/TzThe ratio of the absolute temperature in the cylindrical tube to the combustion explosion temperature of the propellant, η1The relative outflow quantity of the fuel gas in the cylindrical pipe flowing into the external atmosphere environment after the liquid water column is totally sprayed out of the cylindrical pipe,
for the calculation of the coefficient of secondary work, m is the mass of the liquid water column, V is the speed of movement of the liquid water column, VψIs the initial free volume, V, between the nozzle outlet and the liquid column in the cylindrical tube1Increase in free volume caused by gas impacting the liquid column;
energy equation in cylindrical tube system:
step S3.2-2: calculating the internal flow of a gas pipe
Relative outflow equation of gas flowing out in the cylindrical pipe:
where Sd is the cross-sectional area of the outlet of the cylindrical pipe, PaIs the ambient atmospheric pressure.
6. The method for calculating the simulation of the ballistic performance of the gas jet impinging liquid water column according to claim 1, wherein the calculation process of the liquid column movement in the cylindrical pipe in the step S3 is as follows:
equation of motion of the liquid column:
wherein l is the movement displacement of the liquid column, PfFor damping the movement of the fluid column, SnIs the effective thrust area of the gas to the liquid column,
the liquid column mass correction coefficient is obtained;
equation of change of cavity volume:
wherein r' is the vertical distance from the top of the cavity to the inner orifice, and r is the radius of the inner pipe.
7. The method of claim 1, wherein in step S3, the internal ballistic equation set is used to calculate the pressure in the high-pressure chamber and the low-pressure chamber.
8. The method according to claim 7, wherein in step S3, a fourth-order longge-kutta method is used to solve the internal ballistic equation set of the process of the gas jet impacting the liquid column, and the specific calculation method is as follows:
for a first order system of differential equations:
when the variable i is set to 1,2, …, n, the initial value of the differential equation set is yi(t)＝yi0Further, the formula of the fourth order Runge-Kutta method can be written as:
at the right end of the formula h ═ tk+1-tkFor the time step, the assignment formula of each order variable in brackets is as follows:
and (3) gradually iterating by the fourth-order Runge-Kutta method to obtain a numerical solution of a first-order differential equation set formula (12), taking time t as an independent variable for an internal ballistic equation set of the gas jet impacting liquid column balancing body, integrating a time step by calling the fourth-order Runge-Kutta method after each variable is endowed with an initial value, and repeatedly and gradually integrating to obtain ballistic performance parameters.
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