A method for simulating lateral thermal plume interference based on normal temperature helium

Abstract

The application discloses a kind of based on ambient temperature helium's lateral thermal jet interference simulation method, this method includes: according to the research of inflow condition and gas engine jet condition obtains jet and inflow momentum ratio, mass flow ratio;Model and nozzle meet geometric similarity condition, using ambient temperature helium jet simulates real gas jet, according to ground wind tunnel inflow momentum condition and simulation momentum ratio condition, determine the momentum of helium jet, total pressure and mass flow;Using ground wind tunnel test method obtains jet interference wall surface pressure distribution, interference force / torque.The application can be used for ground simulation hot jet interference wind tunnel test.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of thermal jet flow interference ground simulation, and in particular to a simulation method for lateral thermal jet flow interference flow field wall pressure distribution and interference force / torque based on normal temperature helium. BACKGROUND

[0002] Reaction control system (RCS) is also known as lateral jet control technology, which generates direct force on the aircraft through the lateral installation of gas engines to control the attitude or orbit of the aircraft, and is widely used in hypersonic / high supersonic aircraft. The lateral jet is the gas jet generated by the lateral jet engine. When the jet engine is working, the gas jet and the high-speed incoming flow produce complex interference flow containing shock / boundary layer interference, shock / shock interference, flow separation / reattachment, vortex, etc., which changes the aerodynamic force / thermal environment of the whole aircraft and components (wings, rudders, etc.), and generates interference force / torque. Previously, normal temperature air jets with similar pressure ratio and momentum ratio were used to simulate gas jets in ground research, without considering the high temperature, multi-medium and secondary combustion effects (usually collectively referred to as thermal jet effect) of gas jets, to obtain jet interference force / torque, and the simulation accuracy basically meets the engineering application requirements. However, with the development of hypersonic aircraft, especially near-space hypersonic attack / defense weapons, engineering practice results show that the thermal jet effect has a further significant impact, and the interference flow field range, pressure distribution and interference force / torque generated by cold / hot jet interference are significantly different. Therefore, solid rocket engines, Ludwig tubes and other methods are used to provide gas jets to carry out research on thermal jet simulation methods.

[0003] Currently, the thermal jet simulation method simulates the real gas jet interference flow field through high-temperature gas jet, but the thermal jet test needs to carry out ignition test, the test system is relatively complex, the gas jet temperature is high, the measurement is difficult, and the size of the test device for providing gas flow is usually large, which has higher requirements for test model design, so the engineering application range is limited. SUMMARY

[0004] The technical problem to be solved by the present application is to overcome the shortcomings of the prior art and provide a lateral thermal jet flow interference simulation method based on normal temperature helium, which ensures the geometric similarity of the jet nozzle, obtains the normal temperature helium jet parameters by ensuring the momentum ratio of the jet and the incoming flow, and approximately simulates the mass flow ratio at the same simulation momentum ratio, so as to improve the simulation accuracy of the interference flow field pressure distribution and interference force / torque compared with the previous cold jet simulation.

[0005] The technical solution of the present application is:

[0006] A lateral thermal jet flow interference simulation method based on normal temperature helium, comprising:

[0007] The momentum ratio and the mass flow ratio are obtained according to the inflow condition and the jet condition of the gas engine;

[0008] The jet momentum, the total pressure and the mass flow are determined by using the helium jet to simulate the momentum ratio in combination with the inflow condition of the ground wind tunnel.

[0009] The wall pressure distribution or the interference force and torque of the jet interference are obtained by using the ground wind tunnel test method.

[0010] Preferably, the momentum ratio is the ratio of the jet nozzle exit momentum to the inflow momentum, and the mass flow ratio is the ratio of the jet mass flow to the inflow mass flow.

[0011] Preferably, the reference area of the inflow mass flow is selected as an area capable of representing the geometric characteristics of the model.

[0012] Preferably, the momentum ratio

[0013] In the formula: is the jet nozzle exit momentum, is the inflow momentum, P j is the jet static pressure, γ j is the jet specific heat ratio, M j is the jet Mach number, A j is the jet nozzle exit area, P ∞ is the inflow static pressure, γ ∞ is the inflow specific heat ratio, M ∞ is the inflow Mach number, A ∞ is the inflow reference area.

[0014] Preferably, the mass flow ratio is:

[0015] In the formula: is the jet nozzle exit mass flow, is the inflow mass flow, P j is the jet static pressure, R ∞ is the inflow gas constant, R j is the jet gas constant, T ∞ is the inflow gas static temperature, T j is the jet gas static temperature, M j is the jet Mach number, A j is the jet nozzle exit area, P ∞ is the inflow static pressure, M ∞ is the inflow Mach number, A ∞ is the inflow reference area.

[0016] Preferably, the cross-sectional area of the projectile at the jet nozzle axis position is selected as the inflow reference area.

[0017] Preferably, the ground wind tunnel inflow conditions should be consistent with the Mach number of the object of study, and the flow state is consistent.

[0018] Compared with the prior art, the present application has the following advantages:

[0019] (1) Compared with the original cold air simulation, the present application does not need to redesign the internal structure of the model, and uses small-molecule helium gas to approximately simulate the mass flow ratio and total pressure ratio at room temperature; the obtained wall pressure distribution and interference force / torque results are closer to the interference results of the gas hot jet, and the simulation accuracy is higher. Compared with the hot jet simulation method, the present application does not need to install an engine in the model, and does not need to be equipped with an ignition test system and carry out ignition test, thereby reducing the measurement difficulty and test system complexity, and expanding the engineering application range.

[0020] (2) The present application can be used as a supplement to the original pressure ratio and momentum ratio simulation method. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a flow chart of a lateral hot jet interference simulation method based on room temperature helium gas provided by the present application;

[0022] Figure 2 is a schematic diagram of a typical model lateral hot jet layout provided by the present embodiment;

[0023] Figure 3 is a schematic diagram of a lateral hot jet interference flow field provided by the present embodiment;

[0024] Figure 4 is the lateral jet wall pressure distribution result and interference force / torque under the simulation method provided by the present embodiment. DETAILED DESCRIPTION

[0025] Exemplary embodiments of the present disclosure will be described in greater detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be accurately conveyed to those skilled in the art. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0026] The momentum of the cold / hot jet is usually consistent, but the mass flow rate is quite different. The helium gas has small mass, and the present application proposes to simulate the momentum at room temperature and approximately simulate the mass flow rate of the gas jet, develops a helium gas jet simulation method, and provides a new way for ground hot jet simulation.

[0027] Figure 1The application provides a normal-temperature helium-based lateral thermal jet flow interference simulation method flow chart. As shown in the figure, the method comprises the following steps: Figure 1

[0028] Step 1: determining the momentum ratio and mass flow ratio of the jet flow and the incoming flow according to the incoming flow condition and the jet flow condition of the gas engine.

[0029] The momentum ratio is the ratio of the jet flow nozzle outlet momentum and the incoming flow momentum, and the mass flow ratio is the ratio of the jet flow mass flow and the incoming flow mass flow. The reference area for selecting the incoming flow mass flow is an area capable of representing the geometric characteristics of the model.

[0030] Momentum ratio

[0031] In the formula, ρ is the density, u is the speed, the subscript j represents the jet flow, and the subscript ∞ represents the incoming flow.

[0032] The jet flow nozzle outlet momentum is The incoming flow momentum is P j The jet flow static pressure is γ j The jet flow specific heat ratio is M j The jet flow Mach number is A j The jet flow nozzle outlet area is P ∞ The incoming flow static pressure is γ ∞ The incoming flow specific heat ratio is M ∞ The incoming flow Mach number is A ∞ The incoming flow reference area is A

[0033] Mass flow ratio:

[0034] In the formula, The jet flow nozzle outlet mass flow is The incoming flow mass flow is P j The jet flow static pressure is R ∞ The incoming flow gas constant is R j The jet flow gas constant is T ∞ The incoming flow gas static temperature is T j The jet flow gas static temperature is the cross-sectional area of the projectile at the jet flow nozzle axis position, and the cross-sectional area is selected as the incoming flow reference area.

[0035] Step 2: under the condition that the model and the jet flow nozzle satisfy the geometric similarity condition, using the normal-temperature helium jet flow to simulate the real gas jet flow, and according to the ground wind tunnel incoming flow condition, using the helium jet flow to simulate the momentum ratio, and determining the helium jet flow momentum, total pressure and mass flow.

[0036] Momentum ratio:

[0037] Mass flow ratio: ​

[0038] Step 3: Obtain the wall pressure distribution and model disturbance force / moment of the jet interference flow field using wind tunnel tests. The inflow conditions in the ground wind tunnel should be consistent with the inflow Mach number and flow regime of the object under study.

[0039] Example:

[0040] In this embodiment, a typical experimental model was selected as the example to address lateral thermal jet interference. The experimental model is a typical flat plate jet shape. The flat plate has a length L = 330 mm, a width D = 240 mm, a nozzle outlet diameter d = 10 mm, and the nozzle axis is located 180 mm upstream of the flat plate's lateral line. The jet parameters are shown in Table 1, and the incoming flow parameters are shown in Table 2.

[0041] Table 1: Jet Parameters

[0042]

[0043] Table 2: Incoming Flow Parameters

[0044]

[0045] Figure 2 This is a schematic diagram of the lateral thermal jet layout of a typical model in this embodiment. Figure 3 This is a schematic diagram of the lateral thermal jet interference flow field in this embodiment. Figure 4 This embodiment provides the results of the lateral jet wall pressure distribution and the disturbance force / torque under this simulation method. The wall pressure distribution obtained by this simulation method under wind tunnel test is closer to the gas thermal jet disturbance result than the test results of the original cold jet simulation.

[0046] The results show that the helium simulation method described in this invention can significantly improve the accuracy of wall pressure distribution simulation compared with existing air-cooled spray simulations with similar pressure and momentum ratios.

[0047] The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments. For those skilled in the art, various modifications or alterations will be readily apparent within the scope of the claims, and these also fall within the technical scope of the present invention.

Claims

1. A method for simulating lateral thermal jet interference based on room-temperature helium gas, characterized in that, include: The ratio of jet flow to incoming flow and the mass flow rate are obtained based on the incoming flow conditions and the gas engine jet flow conditions. Based on the inflow conditions in the ground wind tunnel, the momentum ratio was simulated using a helium jet to determine the helium jet mobility, total pressure, and mass flow rate. The wall pressure distribution or interference force and torque of jet interference are obtained by ground wind tunnel test method.

2. The method for simulating lateral thermal jet interference based on room-temperature helium gas according to claim 1, characterized in that: The momentum ratio is the ratio of the jet nozzle exit momentum to the incoming momentum, and the mass flow ratio is the ratio of the jet mass flow rate to the incoming mass flow rate.

3. The method for simulating lateral thermal jet interference based on room-temperature helium gas according to claim 2, characterized in that: The reference area for the incoming mass flow rate is an area that can represent the geometric features of the model.

4. The method for simulating lateral thermal jet interference based on room-temperature helium gas according to claim 2, characterized in that: Momentum ratio In the formula: It is the jet nozzle exit momentum. It comes from the flow, P j It is jet static pressure, γ j It is the specific heat ratio of the jet, M j It is the jet Mach number, A j It is the nozzle exit area, P ∞ It is the incoming static pressure, γ ∞ It is the flow-to-heat ratio, M ∞ It is the Mach number of the incoming flow, A ∞ It is the reference area for the incoming flow.

5. The method for simulating lateral thermal jet interference based on room-temperature helium gas according to claim 2, characterized in that: Mass flow ratio: In the formula: It is the mass flow rate at the nozzle exit. It is the incoming quality flow rate, P j It is jet static pressure, R ∞ R is the incoming gas constant. j It is the jet gas constant, T ∞ It is the static temperature of the incoming gas, T j It is the static temperature of the jet gas, M j It is the jet Mach number, A j It is the nozzle exit area, P ∞ It is the incoming static pressure, M ∞ It is the Mach number of the incoming flow, A ∞ It is the reference area for the incoming flow.

6. A method for simulating lateral thermal jet interference based on room-temperature helium gas according to claim 4 or 5, characterized in that: The cross-sectional area of ​​the projectile at the nozzle axis position is selected as the reference area for the incoming flow.

7. The method for simulating lateral thermal jet interference based on room-temperature helium gas according to claim 1, characterized in that: The incoming flow conditions in the ground wind tunnel should be consistent with the Mach number and flow regime of the incoming flow to the object under study.

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