Design method, device and equipment of ultra-high-speed non-ideal gas spray pipe and medium

Abstract

The invention belongs to the technical field of engine nozzles, and relates to a design method, device and equipment of an ultra-high-speed non-ideal gas nozzle and a medium. The method comprises the steps that design parameters are obtained, a non-sticky molded surface and a contraction section of the ultra-high-speed non-ideal gas spraying pipe are designed, and a flow field of the ultra-high-speed non-ideal gas spraying pipe is obtained; carrying out computational fluid mechanics simulation on the flow field by adopting a computational fluid mechanics method, and calculating the boundary layer thickness of the ultra-high-speed non-ideal gas nozzle; according to the thickness of the boundary layer, a non-sticky molded surface and a contraction section of the ultra-high-speed non-ideal gas spraying pipe are redesigned, the thickness of the boundary layer is corrected, and an updated flow field is obtained; performing computational fluid mechanics simulation on the updated flow field by adopting a computational fluid mechanics method to obtain an updated flow field simulation result; and when it is judged that the updated flow field simulation result meets the preset requirement, the current ultra-high-speed non-ideal gas spraying pipe is output. The ultra-high-speed non-ideal gas spray pipe can be accurately designed.

Description

Technical Field

[0001] The present application relates to the field of engine nozzle technology, and in particular to a design method, device, equipment and medium for a hypervelocity non-ideal gas nozzle. Background Art

[0002] For more than a century, wind tunnels have been one of the important testing facilities for aerospace technology. Wind tunnel tests for hypersonic vehicles have higher performance requirements than supersonic vehicles. To produce high-enthalpy test flows in hypersonic wind tunnels, not only does the total temperature need to be high enough to produce obvious non-ideal gas effects, but the flow uniformity also needs to reach a very high level to ensure the accuracy of the experimental data; at the same time, the ideal gas state equation fails under the non-ideal gas effect, and the thick boundary layer causes the thin shear layer equation group to fail. Conventional nozzle design methods have applicability problems and cannot obtain ideal flow fields. Therefore, compared with conventional subsonic or supersonic nozzle designs, the design of hypersonic non-ideal gas nozzles is quite difficult.

[0003] Hypervelocity non-ideal gas nozzles are characterized by high total temperature, high total pressure, and ultra-high speed. The nozzle's contraction section, throat, and part of the supersonic section are high-pressure flows, and the entire nozzle wall area and the above areas are high-temperature flows. Taking the air medium as an example, the vibration energy of oxygen and nitrogen under standard atmospheric pressure is excited when the temperature is greater than 800K, and the specific heat capacity begins to change significantly with temperature; oxygen molecules are ionized when the temperature is greater than 2000K, and are basically all ionized into oxygen atoms when the temperature is greater than 4000K. For the design conditions of hypervelocity non-ideal gas nozzles, Mach 5 generally corresponds to a total temperature of about 1500K, Mach 10 corresponds to a total temperature of about 4500K, and Mach 20 corresponds to about 8000K. These conditions are far beyond the standard atmospheric conditions, the ideal gas assumption is no longer applicable, and the non-ideal gas effect is obvious.

[0004] At the same time, due to the gas viscosity effect, the actual nozzle flow field is different from the inviscid flow field. Due to the existence of viscosity, the boundary layer thickness of the nozzle wall increases with the flow distance, which makes the effective area of ​​the nozzle decrease continuously. Therefore, the actual Mach number at the nozzle outlet is less than the design Mach number. For conventional nozzles, the boundary layer thickness accounts for a very small proportion of the nozzle diameter, which is a small amount compared with the nozzle flow length. Therefore, the thin shear layer assumption is valid, and the boundary layer equations can be used to solve the boundary layer displacement thickness for the viscosity correction of the nozzle profile. However, for hypervelocity non-ideal gas nozzles, the boundary layer thickness increases significantly with the increase of temperature. At this time, the thin shear layer assumption is no longer valid, and the boundary layer equations are invalid, making it difficult to make effective and correct viscosity corrections.

[0005] In the prior art, the variable specific heat ratio Sivells nozzle design method is generally used to design ultra-high-speed non-ideal gas nozzles. The Sivells nozzle design method changes the previous design method from the nozzle wall profile to the internal flow field, which is "from the outside to the inside". The designer independently sets the axis Mach number distribution, and obtains the nozzle profile with continuous curvature throughout the entire process through reverse design "from the inside to the outside".

[0006] like Figure 1 As shown in the figure, the design of the inviscid profile is the transonic region of the throat (ITH region), the conical source flow region (EBAG region), and the uniform flow region of the nozzle outlet (CD downstream) from upstream to downstream. Each of the two is matched and connected by the characteristic line design region (IEGH region, BCDA region) of the preset axial velocity distribution to achieve the continuity of the second-order derivative of the overall axial velocity, and the derivative is 0 at the exit point, thereby realizing the inviscid nozzle design with higher flow field quality.

[0007] The specific design process of the variable specific heat ratio nozzle is as follows:

[0008] ① Calculate the flow field in the HIEG area. The temperature in this area is very high. The specific heat ratio γ2 adopts the average value of this area to obtain the initial expansion section profile curve HG.

[0009] ② Calculate the flow field in the ABCD area. At this time, the nozzle flow field has basically reached the ideal gas state. The specific heat capacity ratio adopts the average value of this area, and the wave-breaking section profile curve AD is calculated.

[0010] ③ Calculate the area ratio requirement that needs to be met after the specific heat ratio changes to determine the length of the straight segment GA, so that the initial expansion segment profile curve HG, the wave-absorbing segment profile curve AD, and the straight segment GA match and meet the area ratio requirement.

[0011] ④ Then introduce the empirical relationship 1.2 of the friction coefficient and the empirical relationship 1.3 of the shape factor to close the momentum integral relationship 1.1, and combine the reference enthalpy method to solve the boundary layer displacement thickness to achieve the viscosity correction of the nozzle.

[0012]

[0013] C fi =0.0773 / (logR θi +4.563)×(logR θi -0.546) (1.2)

[0014] H i =(1-7(C fi / 2) 1 / 2 ) -1 (1.3)

[0015] The above-mentioned Sivells method successfully avoids the obvious compression wave inside the nozzle, achieves uniform Mach number distribution at the nozzle outlet, and significantly improves the quality of the flow field. To date, the Sivells method is still the mainstream design method abroad.

[0016] However, the prior art including the Sivells method still has the following disadvantages:

[0017] (1) The existing technology still designs inviscid nozzles based on the characteristic line method. The characteristic line control equation is the gas dynamics equation, namely, Equation 1.4, which is derived based on the inviscid and irrotational ideal gas state. Although the characteristic line method is mainstream and advanced for designing conventional nozzles, it is not applicable to high-speed non-ideal gas nozzles, which are high-temperature, high-pressure, and high-Mach number nozzles with obvious non-ideal gas effects, and has large errors. Abroad, Benton et al. analyzed in detail the limitations of the characteristic line method in the design of hypersonic nozzles, pointing out that it is effective for nozzle design with Mach numbers ≤8, but unreliable for hypersonic nozzles with Mach numbers >8. In other words, the design method of the existing technology is based on ideal gas conditions and is not applicable to hypersonic non-ideal gas nozzles.

[0018]

[0019] (2) The boundary layer of the hypervelocity non-ideal gas nozzle is very thick, the thin shear layer assumption does not hold, and the boundary layer equation is invalid. At the same time, the influence of non-ideal gas on the development of the boundary layer cannot be considered. Therefore, the displacement thickness calculated using the momentum integral relationship is inaccurate. Summary of the invention

[0020] Based on this, it is necessary to provide a design method, device, equipment and medium for an ultra-high-speed non-ideal gas nozzle in response to the above-mentioned technical problems, which can accurately design the ultra-high-speed non-ideal gas nozzle and obtain an ideal flow field.

[0021] The design method of hypervelocity non-ideal gas nozzle includes:

[0022] The design parameters of the hypervelocity non-ideal gas nozzle are obtained, and the inviscid surface of the hypervelocity non-ideal gas nozzle is designed by using the characteristic line method; the contraction section of the hypervelocity non-ideal gas nozzle is designed according to the inviscid surface; the flow field of the hypervelocity non-ideal gas nozzle is obtained according to the inviscid surface and the contraction section;

[0023] Using a computational fluid dynamics method, a computational fluid dynamics simulation is performed on the flow field to obtain a flow field simulation result;

[0024] The boundary layer thickness of the hypervelocity non-ideal gas nozzle is calculated using computational fluid dynamics methods.

[0025] According to the boundary layer thickness, the inviscid surface and the contraction section of the hypervelocity non-ideal gas nozzle are redesigned, and the boundary layer thickness is corrected according to the flow field simulation result to obtain an updated flow field; a computational fluid dynamics method is used to perform a computational fluid dynamics simulation on the updated flow field to obtain an updated flow field simulation result;

[0026] When it is determined that the updated flow field simulation results meet the preset requirements, the current hypervelocity non-ideal gas nozzle is output.

[0027] In one embodiment, a computational fluid dynamics method is used to perform computational fluid dynamics simulation on the flow field to obtain a flow field simulation result, including:

[0028] By using computational fluid dynamics methods and considering the non-ideal gas effect, the gas dynamics equation of the hypervelocity non-ideal gas nozzle is obtained:

[0029]

[0030] Where P is pressure, R is the universal gas constant, T is temperature, V is the molar volume of the gas, and b and α are different van der Waals gas constants;

[0031] Using computational fluid dynamics methods and considering the temperature range of high enthalpy flow, the specific heat capacity of the hypervelocity non-ideal gas nozzle is obtained:

[0032] Cp(T)=a0+a1T+a2T 2 +a3T 3 +a4T 4

[0033] In the formula, Cp is the specific heat capacity, a0, a1, a2, a3, a4 are the fitting coefficients of different gas components;

[0034] The gas dynamics equation and the specific heat capacity are used as flow field simulation results.

[0035] In one embodiment, a computational fluid dynamics method is used to calculate the boundary layer thickness of a hypervelocity non-ideal gas nozzle, including:

[0036]

[0037] In the formula, δ * is the displacement thickness of the boundary layer, δ is the thickness of the boundary layer, ρ is the density, u is the velocity, ρ e is the density at the outer edge of the boundary layer, u e is the velocity at the outer edge of the boundary layer, and y is the y-axis coordinate.

[0038] In one embodiment, the design parameters of the hypervelocity non-ideal gas nozzle are obtained, and the inviscid surface of the hypervelocity non-ideal gas nozzle is designed by using the characteristic line method, including:

[0039] The design parameters of the hypervelocity non-ideal gas nozzle are obtained, and the throat area of ​​the ideal gas is obtained according to the mass conservation law; the throat area is corrected by using the Eggers method to obtain the corrected throat area;

[0040] According to the design parameters of the hypervelocity non-ideal gas nozzle, the B-Spline curve is obtained;

[0041] According to the design parameters of the hypervelocity non-ideal gas nozzle and the hyperbolic mathematical properties of supersonic gas dynamics, the characteristic line equation and compatibility equation of the flow are obtained.

[0042] According to the modified throat area, B-Spline curve, characteristic line equation and compatibility equation, the inviscid surface of the hypervelocity non-ideal gas nozzle is obtained.

[0043] In one embodiment, the design parameters of the hypervelocity non-ideal gas nozzle are obtained, and the throat area of ​​the ideal gas is obtained according to the law of mass conservation, including:

[0044]

[0045] In the formula, is the throat area, i is the result under ideal gas conditions, A e is the nozzle exit area, Ma is the design Mach number, γ is the gas specific heat ratio;

[0046] The Eggers method is used to correct the throat area to obtain a corrected throat area, including:

[0047]

[0048]

[0049] In the formula, A * is the throat area under non-ideal gas conditions, F is the correction function, θ is the vibration characteristic temperature of the gas, T0 is the total temperature, ρ0 is the stagnation density, b is the molar volume constant, c is the intermolecular force constant, R is the gas constant, e is the exponent with the natural number e as the base, B4, C4, and D4 are different correlation coefficients;

[0050] According to the design parameters of the hypervelocity non-ideal gas nozzle, the B-Spline curve is obtained, including:

[0051] P i (u)=[u 3 u 2 u 1]B N,i [V i V i+1 V i+2V i+3 ] T (i=1,2,…,N-1,N)

[0052] Where P i (u) is the B-spline curve, B N,i is the i-th basis function matrix of the N-th vertex, V i is the control point, T is the transpose, 0≤u≤1, N>3;

[0053] According to the design parameters of the hyperbolic gas nozzle and the hyperbolic mathematical properties of supersonic gas dynamics, the characteristic line equation and compatibility equation of the flow are obtained, including:

[0054]

[0055]

[0056] Where y is the y-axis coordinate, x is the x-axis coordinate, θ is the stream angle, μ is the Mach angle, M is the Mach number, γ is the specific heat ratio, and δ is the flow characteristic factor.

[0057] In one embodiment, according to the non-stick surface, the contraction section of the hypervelocity non-ideal gas nozzle is designed, including:

[0058]

[0059] Where y is the y-axis coordinate, t is the throat height, y i is the height of the inlet of the contraction section, x is the x-axis coordinate, L c is the length of the contraction section.

[0060] In one embodiment, according to the inviscid profile and the contraction section, a flow field of a hypervelocity non-ideal gas nozzle is obtained, including:

[0061] shortening the downstream portion of the non-stick profile to obtain an updated non-stick profile;

[0062] According to the updated inviscid profile and the contraction section, the flow field of the ultra-high-speed non-ideal gas nozzle is obtained.

[0063] The design device of the hypervelocity non-ideal gas nozzle includes:

[0064] A design module is used to obtain design parameters of a hypervelocity non-ideal gas nozzle, and to design an inviscid profile of the hypervelocity non-ideal gas nozzle by using a characteristic line method; to design a contraction section of the hypervelocity non-ideal gas nozzle according to the inviscid profile; and to obtain a flow field of the hypervelocity non-ideal gas nozzle according to the inviscid profile and the contraction section;

[0065] A simulation module, used to perform computational fluid dynamics simulation on the flow field using a computational fluid dynamics method to obtain a flow field simulation result;

[0066] A calculation module for calculating the boundary layer thickness of a hypervelocity non-ideal gas nozzle using a computational fluid dynamics method;

[0067] An iteration module is used to redesign the inviscid surface and the contraction section of the hypervelocity non-ideal gas nozzle according to the boundary layer thickness, and to correct the boundary layer thickness according to the flow field simulation result to obtain an updated flow field; and to perform a computational fluid dynamics simulation on the updated flow field using a computational fluid dynamics method to obtain an updated flow field simulation result;

[0068] The judgment module is used to output the current hypervelocity non-ideal gas nozzle when judging whether the updated flow field simulation result meets the preset requirements.

[0069] A computer device comprises a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the following steps are implemented:

[0070] The design parameters of the hypervelocity non-ideal gas nozzle are obtained, and the inviscid surface of the hypervelocity non-ideal gas nozzle is designed by using the characteristic line method; the contraction section of the hypervelocity non-ideal gas nozzle is designed according to the inviscid surface; the flow field of the hypervelocity non-ideal gas nozzle is obtained according to the inviscid surface and the contraction section;

[0071] Using a computational fluid dynamics method, a computational fluid dynamics simulation is performed on the flow field to obtain a flow field simulation result;

[0072] The boundary layer thickness of the hypervelocity non-ideal gas nozzle is calculated using computational fluid dynamics methods.

[0073] According to the boundary layer thickness, the inviscid surface and the contraction section of the hypervelocity non-ideal gas nozzle are redesigned, and the boundary layer thickness is corrected according to the flow field simulation result to obtain an updated flow field; a computational fluid dynamics method is used to perform a computational fluid dynamics simulation on the updated flow field to obtain an updated flow field simulation result;

[0074] When it is determined that the updated flow field simulation results meet the preset requirements, the current hypervelocity non-ideal gas nozzle is output.

[0075] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the following steps:

[0076] The design parameters of the hypervelocity non-ideal gas nozzle are obtained, and the inviscid surface of the hypervelocity non-ideal gas nozzle is designed by using the characteristic line method; the contraction section of the hypervelocity non-ideal gas nozzle is designed according to the inviscid surface; the flow field of the hypervelocity non-ideal gas nozzle is obtained according to the inviscid surface and the contraction section;

[0077] Using a computational fluid dynamics method, a computational fluid dynamics simulation is performed on the flow field to obtain a flow field simulation result;

[0078] The boundary layer thickness of the hypervelocity non-ideal gas nozzle is calculated using computational fluid dynamics methods.

[0079] According to the boundary layer thickness, the inviscid surface and the contraction section of the hypervelocity non-ideal gas nozzle are redesigned, and the boundary layer thickness is corrected according to the flow field simulation result to obtain an updated flow field; a computational fluid dynamics method is used to perform a computational fluid dynamics simulation on the updated flow field to obtain an updated flow field simulation result;

[0080] When it is determined that the updated flow field simulation results meet the preset requirements, the current hypervelocity non-ideal gas nozzle is output.

[0081] The design method, device, equipment and medium of the above-mentioned ultra-high-speed non-ideal gas nozzle are designed to solve the problem that the conventional characteristic line and boundary layer correction method is difficult to design the ultra-high-speed non-ideal gas nozzle and difficult to obtain the ideal flow field. Specifically, the inviscid profile and contraction section of the nozzle are designed based on the characteristic line, the nozzle is shortened, and the nozzle flow field is calculated based on computational fluid dynamics, and then it is iterated. In this application, there is no single computational fluid dynamics optimization method lacking the theoretical guidance of nozzle design or a single characteristic line method that is no longer suitable for the non-ideal gas effect. Instead, the nozzle is iteratively designed by combining computational fluid dynamics and the characteristic line method, which has the computational advantages of calculating the non-ideal gas effect and the theoretical advantages of designing the nozzle wave system; the nozzle flow field is simulated by computational fluid dynamics, and the simulation results are used for viscosity correction and iterative design, which can optimize the flow field and is applicable to: (hyper) supersonic wind tunnels, engine nozzles, aerodynamic experimental equipment and other technical fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0082] Figure 1 Schematic diagram of the Sivells nozzle design;

[0083] Figure 2 is an application scenario diagram of a design method for a hypervelocity non-ideal gas nozzle in one embodiment;

[0084] Figure 3 A schematic diagram of a process for designing a hypervelocity non-ideal gas nozzle in one embodiment;

[0085] Figure 4 The non-stick surface of the nozzle designed in one embodiment;

[0086] Figure 5 A schematic diagram of a nozzle being shortened in one embodiment;

[0087] Figure 6 A schematic diagram of a nozzle computational domain mesh in one embodiment;

[0088] Figure 7 is a boundary layer displacement thickness obtained based on computational fluid dynamics data in one embodiment;

[0089] Figure 8 A schematic diagram of the design architecture of a hypervelocity non-ideal gas nozzle in one embodiment;

[0090] Fig. 9 The profile of a Mach 10 hyperspeed non-ideal gas nozzle designed in one embodiment;

[0091] Fig.10 A Mach number cloud diagram of a Mach 10 hyperspeed non-ideal gas nozzle designed in one embodiment;

[0092] Fig.11 is a contour diagram of a Mach 10 hyperspeed non-ideal gas nozzle designed in one embodiment;

[0093] Fig.12 : is the outlet Mach number distribution of a Mach 10 hypervelocity non-ideal gas nozzle designed in one embodiment;

[0094] Fig.13 is a structural block diagram of a design device for a super-high-speed non-ideal gas nozzle in one embodiment;

[0095] Fig.14 FIG. 4 is a diagram showing the internal structure of a computer device in one embodiment. DETAILED DESCRIPTION

[0096] In order to make the purpose, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0097] It should be noted that all directional indications in the embodiments of the present application (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0098] In addition, the descriptions of "first", "second", etc. in this application are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, "multiple groups" means at least two groups, such as two groups, three groups, etc., unless otherwise clearly and specifically defined.

[0099] In this application, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0100] In addition, the technical solutions between the various embodiments of the present application can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0101] The method provided in this application can be applied to Figure 2 In the application environment shown, the terminal 202 communicates with the server 204 through the network, and the terminal 202 may include but is not limited to various personal computers, laptops, smart phones, tablet computers and portable wearable devices, and the server 204 may be various portal websites, servers corresponding to the backend of the work system, etc.

[0102] The present application provides a design method for a hypervelocity non-ideal gas nozzle, such as Figure 3 As shown, in one embodiment, the method is applied to Figure 2 The following is an example of a terminal in the example, including:

[0103] Step 302, obtaining the design parameters of the hypervelocity non-ideal gas nozzle, and using the characteristic line method to design the inviscid surface of the hypervelocity non-ideal gas nozzle; based on the inviscid surface, designing the contraction section of the hypervelocity non-ideal gas nozzle; based on the inviscid surface and the contraction section, obtaining the flow field of the hypervelocity non-ideal gas nozzle.

[0104] Specifically, the design parameters of the hypervelocity non-ideal gas nozzle are obtained, and the inviscid surface of the hypervelocity non-ideal gas nozzle is designed by using the characteristic line method, including:

[0105] The design parameters of the hypervelocity non-ideal gas nozzle are obtained, and the throat area of ​​the ideal gas is obtained according to the law of mass conservation; the throat area is corrected using the Eggers method to obtain the corrected throat area;

[0106] According to the design parameters of the hypervelocity non-ideal gas nozzle, the B-Spline curve is obtained;

[0107] According to the design parameters of the hypervelocity non-ideal gas nozzle and the hyperbolic mathematical properties of supersonic gas dynamics, the characteristic line equation and compatibility equation of the flow are obtained.

[0108] According to the modified throat area, B-Spline curve, characteristic line equation and compatibility equation, the inviscid surface of the hypervelocity non-ideal gas nozzle is obtained.

[0109] More specifically:

[0110] According to the needs of scientific research or engineering, the design parameters of the hypervelocity non-ideal gas nozzle are obtained, and the design Mach number and exit height are obtained. According to the law of mass conservation, the relationship between the Mach number and the area ratio of the ideal gas is obtained, and the throat area of ​​the ideal gas is obtained, including:

[0111]

[0112] In the formula, A i * is the throat area, i is the result under ideal gas conditions, A e is the nozzle exit area, Ma is the design Mach number, γ is the gas specific heat ratio;

[0113] Taking into account the high temperature / real gas effect of the nozzle, that is, the non-ideal gas effect, the specific heat ratio of the nozzle changes. The Berthelot state equation takes into account the molecular size and intermolecular force effects. The change in vibration heat capacity is given by the Planck term. The Eggers method is used to correct the throat area to obtain the corrected throat area, including:

[0114] A * =A i * F(θ,T0,Ma) (1.6)

[0115]

[0116] In the formula, A * is the throat area under non-ideal gas conditions, F is the correction function, θ is the vibration characteristic temperature of the gas, T0 is the total temperature, ρ0 is the stagnation density, b is the molar volume constant, c is the intermolecular force constant, R is the gas constant, e is the exponent with the natural number e as the base, B4, C4, and D4 are different correlation coefficients;

[0117] in:

[0118]

[0119]

[0120]

[0121] In the formula, γ i is the specific heat ratio under ideal gas conditions, Γ i For γ i The functional relationship Γ i =(γ i 2 -3γ i +3), ρ is the density, ρ0 is the density under stagnation conditions, ρ * is the critical density, T is the static temperature, T * is the critical temperature, B1, C1, D1 are different specific heat ratios γ under ideal gas conditions i , pressure P, density ρ, and coefficients of the vibration characteristic temperature θ of the gas, the specific values ​​of which are based on the prior art.

[0122] For transonic flow at the nozzle throat, the gas dynamics equation, equation 1.4, is parabolic and therefore difficult to solve directly. The traditional Foelsch and Cresci nozzle design uses the source flow assumption to simplify the flow near the throat, and the error introduced by this is unacceptable for high Mach number nozzles.

[0123] According to the design parameters of the hyperspeed non-ideal gas nozzle, the present application adopts Hall's method to linearize the potential function equation through series expansion, obtains a transonic solution (how to obtain a transonic solution belongs to the prior art), determines the axis starting point Mach number and the Mach number derivative; the axis Mach number distribution of the ASN adopts the B-spline function to ensure continuous second-order derivatives; therefore, the B-Spline curve is obtained, including:

[0124] P i (u)=[u 3 u 2 u 1]BN,i [V i V i+1 V i+2 V i+3 ] T (i=1,2,…,N-1,N) (1.11)

[0125] Where P i (u) is the B-spline curve (i.e., B-spline function), B N,i is the i-th basis function matrix of the N-th vertex, V i is a control point used to adjust the shape of the curve, T is the transpose, 0≤u≤1, N>3;

[0126] With the transonic solution and the axis velocity distribution as boundary conditions, the inviscid flow field is inversely designed using the characteristic line method. According to the design parameters of the hyperbolic non-ideal gas nozzle, the potential function equation is hyperbolic and can be solved in space step by step. Based on the hyperbolic mathematical properties of supersonic gas dynamics, the characteristic line equation and compatibility equation of the flow are obtained, including:

[0127]

[0128]

[0129] Where y is the y-axis coordinate, x is the x-axis coordinate, θ is the stream angle, μ is the Mach angle, M is the Mach number, γ is the specific heat ratio, and δ is the flow characteristic factor.

[0130] The inviscid surface of the designed hypervelocity non-ideal gas nozzle is shown in Figure 4 As shown, where y i is the entrance height, y e is the outlet height, R t is the throat radius, R d It is a 1 / 4 diamond area.

[0131] At the same time, according to the inviscid surface, the contraction section of the hypervelocity non-ideal gas nozzle is designed, and the fifth power contraction section method is adopted. Its control equation includes:

[0132]

[0133] Where y is the y-axis coordinate, t is the throat height, y i is the height of the inlet of the contraction section, x is the x-axis coordinate, L c is the length of the contraction section.

[0134] Hypersonic non-ideal gas nozzles are usually very long, and their length varies with design methods and geometric parameters (such as expansion angle and exit height). However, due to the characteristics of hypersonic flow, in the streamline coordinate system, the streamwise component of the velocity is much larger than the normal component of the speed of sound, resulting in the nozzle rhombus length being much larger than the height. Considering the high cost and thick boundary layer of the nozzle, it is hoped that the nozzle can be shortened while ensuring flow uniformity. Flow uniformity can be evaluated by computational fluid dynamics methods, and the truncation position is generally determined according to engineering applications.

[0135] Therefore, according to the inviscid surface and the contraction section of the supersonic section, the flow field of the hypervelocity non-ideal gas nozzle is obtained, including: shortening the downstream part of the inviscid surface to obtain an updated inviscid surface; according to the updated inviscid surface and the contraction section, obtaining the overall surface of the hypervelocity non-ideal gas nozzle, and then obtaining the flow field of the hypervelocity non-ideal gas nozzle.

[0136] like Figure 5 As shown in the figure, the shortening of the nozzle length leads to a reduction in the actual diamond area height and length, ensuring that the test requirements can be met. s is the nozzle section, T s is the test segment, C p is the cutoff position, y t is the throat height, y d is the height of the nozzle diamond, y d ' is the height of the truncated nozzle diamond area.

[0137] Step 304: Use a computational fluid dynamics method to perform computational fluid dynamics simulation on the flow field to obtain a flow field simulation result.

[0138] Specifically:

[0139] According to the physical problem being calculated, set the appropriate flow model, gas state equation, specific heat capacity relationship and other options. In this application, the compressible Reynolds-averaged Navier–Stokes (RANS) equations combined with the turbulence model are used to calculate the nozzle flow.

[0140] By using computational fluid dynamics method and considering the non-ideal gas effect, the gas dynamics equation of the hypervelocity non-ideal gas nozzle is obtained using the Aungier-Redlich-Kwong equation:

[0141]

[0142] Where P is pressure, R is the universal gas constant, T is temperature, V is the molar volume of the gas, and b and α are different van der Waals gas constants;

[0143] Using computational fluid dynamics methods, considering the wide temperature change range of high enthalpy flow, the specific heat capacity uses NASA's piecewise polynomial fitting coefficients to obtain the specific heat capacity of the hypervelocity non-ideal gas nozzle:

[0144] Cp(T)=a0+a1T+a2T 2 +a3T 3 +a4T 4 (1.16)

[0145] In the formula, Cp is the specific heat capacity, a0, a1, a2, a3, a4 are the fitting coefficients of different gas components, which can be obtained by looking up the table;

[0146] The gas dynamics equation and specific heat capacity are used as the flow field simulation results. The specific computational domain grid is automatically generated using transfinite interpolation (TFI) technology to ensure that the first layer of wall grid meets the requirements of the turbulence model, such as Figure 6 As shown, O i For the entrance, O e For export, A x is the symmetry axis, P n It is the nozzle profile.

[0147] In this step, the uniformity of the flow in the truncated nozzle can be simulated by computational fluid dynamics methods, specifically using CFD or other solvers. In addition, if the nozzle is used in a shock tunnel, the chemical non-equilibrium effect can be considered using the Park dual temperature model.

[0148] Step 306, using computational fluid dynamics methods to calculate the boundary layer thickness of the hypervelocity non-ideal gas nozzle.

[0149] Specifically:

[0150]

[0151] In the formula, δ * is the displacement thickness of the boundary layer, δ is the thickness of the boundary layer (the distance from the outer edge of the boundary layer to the nozzle profile), ρ is the density, u is the velocity, ρ e is the density at the outer edge of the boundary layer, u e is the velocity at the outer edge of the boundary layer, and y is the y-axis coordinate.

[0152] In this step, for the thick boundary layer of the nozzle, the thin shear layer assumption has failed, and the boundary layer displacement thickness solved by the existing method through the momentum integral relationship is no longer accurate. Based on the computational fluid dynamics data, this application obtains the boundary layer thickness according to the definition of displacement thickness, such as Figure 7 shown.

[0153] Step 308, according to the boundary layer thickness, redesign the inviscid surface and the contraction section of the ultra-high-speed non-ideal gas nozzle, and correct the boundary layer thickness according to the flow field simulation results to obtain an updated flow field; use the computational fluid dynamics method to perform computational fluid dynamics simulation on the updated flow field to obtain an updated flow field simulation result.

[0154] In this step, the above steps are cycled and will not be described again.

[0155] Step 310: When it is determined that the updated flow field simulation result meets the preset requirements, the current hypervelocity non-ideal gas nozzle is output.

[0156] In this step, when it is determined that the updated flow field simulation result does not meet the preset requirements: recalculate the boundary layer thickness of the hypervelocity non-ideal gas nozzle; redesign the inviscid surface and contraction section of the hypervelocity non-ideal gas nozzle according to the boundary layer thickness, and correct the boundary layer thickness according to the updated flow field simulation result to obtain the next flow field; use the computational fluid dynamics method to perform computational fluid dynamics simulation on the next flow field to obtain the next flow field simulation result; judge the next flow field simulation result until it meets the preset requirements, and output the current hypervelocity non-ideal gas nozzle.

[0157] In this embodiment, the complete nozzle design architecture is as follows Figure 8 As shown. After inputting the nozzle design parameters, the inviscid nozzle profile is first designed based on the characteristic line method, the nozzle contraction section is designed, and the inviscid nozzle profile is shortened; then the nozzle flow is calculated and simulated by computational fluid dynamics; according to the computational fluid dynamics data, the boundary layer displacement thickness of the nozzle is calculated based on the displacement thickness definition; according to the boundary layer displacement thickness distribution, the characteristic line method is used again to design the inviscid nozzle profile, and truncation and viscosity correction are performed; then the new nozzle is calculated and simulated by computational fluid dynamics; if the flow field indicators do not meet the requirements, the boundary layer thickness is recalculated and iterated; if it meets the requirements, the design is completed. The design process uses Matlab, Visual Studio, Tecplot and Fluent software, and the entire design process is automated through the Command Prompt of Microsoft Windows. The design process only requires the designer to submit the design requirements, and the computer will realize the nozzle iterative design.

[0158] The above-mentioned design method of the ultra-high-speed non-ideal gas nozzle is designed to solve the problem that the conventional characteristic line and boundary layer correction method is difficult to design the ultra-high-speed non-ideal gas nozzle and difficult to obtain the ideal flow field. An ultra-high-speed non-ideal gas nozzle iterative design method based on computational fluid dynamics and characteristic line method is designed. Specifically, the inviscid profile and contraction section of the nozzle are designed based on the characteristic line, the nozzle is shortened, and the nozzle flow field is calculated based on computational fluid dynamics, and then it is iterated. In this application, there is no single computational fluid dynamics optimization method lacking the theoretical guidance of nozzle design or a single characteristic line method that is no longer suitable for the non-ideal gas effect. Instead, the nozzle is iteratively designed by combining computational fluid dynamics and characteristic line method, which has the computational advantages of calculating the non-ideal gas effect and the theoretical advantages of designing the nozzle wave system; the nozzle flow field is simulated by computational fluid dynamics, and the simulation results are used for viscosity correction and iterative design, which can optimize the flow field and is applicable to: (hyper) supersonic wind tunnels, engine nozzles, aerodynamic experimental equipment and other technical fields.

[0159] It should be understood that although Figure 3 The steps in the flowchart are shown in sequence as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover, Figure 3 At least part of the steps may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least part of the sub-steps or stages of other steps.

[0160] In a specific embodiment, the design parameters are input as follows: Mach 10, length 14 meters, nozzle outlet height 2.5 meters, total pressure of incoming flow 15 MPa, total temperature 4500K, and the method of the present application is used for iterative design. The result is as follows Figures 9 to 12 As shown. It can be seen that the nozzle Mach number contour lines are distributed regularly, the nozzle wall wave is completely eliminated, and the outlet Mach number is evenly distributed; at the axis Y = 0m, the nozzle outlet Mach number Ma = 10.000, at the axis Y = 0.7m, the nozzle outlet Mach number Ma = 10.022, the relative error of the Mach number is about 1‰, and the uniformity is high.

[0161] The present application also provides a design device for a hypervelocity non-ideal gas nozzle, such as Fig.13 As shown, in one embodiment, it includes: a design module 1302, a simulation module 1304, a calculation module 1306, an iteration module 1308 and a judgment module 1310, wherein:

[0162] The design module is used to obtain the design parameters of the hypervelocity non-ideal gas nozzle and use the characteristic line method to design the inviscid surface of the hypervelocity non-ideal gas nozzle; based on the inviscid surface, the contraction section of the hypervelocity non-ideal gas nozzle is designed; based on the inviscid surface and the contraction section, the flow field of the hypervelocity non-ideal gas nozzle is obtained;

[0163] A simulation module is used to perform computational fluid dynamics simulation on the flow field using computational fluid dynamics methods to obtain flow field simulation results;

[0164] A calculation module for calculating the boundary layer thickness of a hypervelocity non-ideal gas nozzle using a computational fluid dynamics method;

[0165] An iteration module is used to redesign the inviscid surface and the contraction section of the hypervelocity non-ideal gas nozzle according to the boundary layer thickness, and to correct the boundary layer thickness according to the flow field simulation result to obtain an updated flow field; and to perform a computational fluid dynamics simulation on the updated flow field using a computational fluid dynamics method to obtain an updated flow field simulation result;

[0166] The judgment module is used to output the current hypervelocity non-ideal gas nozzle when judging whether the updated flow field simulation result meets the preset requirements.

[0167] The specific definition of the design device of the hypervelocity non-ideal gas nozzle can be found in the definition of the design method of the hypervelocity non-ideal gas nozzle mentioned above, which will not be repeated here. Each module in the above device can be implemented in whole or in part by software, hardware and a combination thereof. Each of the above modules can be embedded in or independent of the processor in the computer device in the form of hardware, or can be stored in the memory of the computer device in the form of software, so that the processor can call and execute the operations corresponding to each of the above modules.

[0168] In one embodiment, a computer device is provided. The computer device may be a terminal, and its internal structure diagram may be as follows: Fig.14As shown. The computer device includes a processor, a memory, a network interface, a display screen and an input device connected through a system bus. 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 and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The network 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 design method for an ultra-high-speed non-ideal gas nozzle is implemented. The display screen of the computer device can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device can be a touch layer covered on the display screen, or a key, trackball or touchpad set on the computer device housing, or an external keyboard, touchpad or mouse, etc.

[0169] 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.

[0170] In one embodiment, a computer device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the method in the above embodiment when executing the computer program.

[0171] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps of the method in the above embodiment are implemented.

[0172] 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 memory, storage, database or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0173] 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.

[0174] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A design method for a hypervelocity non-ideal gas nozzle, characterized in that: include: Obtain the design parameters of the hypervelocity non-ideal gas nozzle, and use the characteristic line method to design the inviscid surface of the hypervelocity non-ideal gas nozzle; According to the inviscid profile, a contraction section of a hypervelocity non-ideal gas nozzle is designed; According to the inviscid surface and the contraction section, a flow field of a hypervelocity non-ideal gas nozzle is obtained; Using a computational fluid dynamics method, a computational fluid dynamics simulation is performed on the flow field to obtain a flow field simulation result; The boundary layer thickness of the hypervelocity non-ideal gas nozzle is calculated using computational fluid dynamics methods. According to the boundary layer thickness, the inviscid surface and the contraction section of the hypervelocity non-ideal gas nozzle are redesigned, and according to the flow field simulation result, the boundary layer thickness is corrected to obtain an updated flow field; Using a computational fluid dynamics method, a computational fluid dynamics simulation is performed on the updated flow field to obtain an updated flow field simulation result; When it is determined that the updated flow field simulation results meet the preset requirements, the current hypervelocity non-ideal gas nozzle is output.

2. The design method of the ultra-high-speed non-ideal gas nozzle according to claim 1, characterized in that: The flow field is simulated by computational fluid dynamics method to obtain flow field simulation results, including: By using computational fluid dynamics methods and considering the non-ideal gas effect, the gas dynamics equation of the hypervelocity non-ideal gas nozzle is obtained: Where P is pressure, R is the universal gas constant, T is temperature, V is the molar volume of the gas, and b and α are different van der Waals gas constants; Using computational fluid dynamics methods and considering the temperature range of high enthalpy flow, the specific heat capacity of the hypervelocity non-ideal gas nozzle is obtained: Cp(T)=a0+a1T+a2T 2 +a3T 3 +a4T 4 In the formula, Cp is the specific heat capacity, a0, a1, a2, a3, a4 are the fitting coefficients of different gas components; The gas dynamics equation and the specific heat capacity are used as flow field simulation results.

3. The design method of the ultra-high-speed non-ideal gas nozzle according to claim 2, characterized in that: The boundary layer thickness of the hypervelocity non-ideal gas nozzle is calculated using computational fluid dynamics methods, including: In the formula, δ * is the displacement thickness of the boundary layer, δ is the thickness of the boundary layer, ρ is the density, u is the velocity, ρ e is the density at the outer edge of the boundary layer, u e is the velocity at the outer edge of the boundary layer, and y is the y-axis coordinate.

4. The method for designing a hypervelocity non-ideal gas nozzle according to any one of claims 1 to 3, characterized in that: The design parameters of the hypervelocity non-ideal gas nozzle are obtained, and the inviscid surface of the hypervelocity non-ideal gas nozzle is designed using the characteristic line method, including: The design parameters of the hypervelocity non-ideal gas nozzle are obtained, and the throat area of ​​the ideal gas is obtained according to the mass conservation law; the throat area is corrected by using the Eggers method to obtain the corrected throat area; According to the design parameters of the hypervelocity non-ideal gas nozzle, the B-Spline curve is obtained; According to the design parameters of the hypervelocity non-ideal gas nozzle and the hyperbolic mathematical properties of supersonic gas dynamics, the characteristic line equation and compatibility equation of the flow are obtained. According to the modified throat area, B-Spline curve, characteristic line equation and compatibility equation, the inviscid surface of the hypervelocity non-ideal gas nozzle is obtained.

5. The design method of the ultra-high-speed non-ideal gas nozzle according to claim 4, characterized in that: Obtain the design parameters of the hypervelocity non-ideal gas nozzle and obtain the throat area of ​​the ideal gas based on the law of mass conservation, including: In the formula, A i * is the throat area, i is the result under ideal gas conditions, A e is the nozzle exit area, Ma is the design Mach number, γ is the gas specific heat ratio; The Eggers method is used to correct the throat area to obtain a corrected throat area, including: A * =A i * ·F(θ,T0,Ma) In the formula, A * is the throat area under non-ideal gas conditions, F is the correction function, θ is the vibration characteristic temperature of the gas, T0 is the total temperature, ρ0 is the stagnation density, b is the molar volume constant, c is the intermolecular force constant, R is the gas constant, e is the exponent with the natural number e as the base, B4, C4, and D4 are different correlation coefficients; According to the design parameters of the hypervelocity non-ideal gas nozzle, the B-Spline curve is obtained, including: P i (u)=[u 3 u 2 u 1]B N,i [V i V i+1 V i+2 V i+3 ] T (i=1,2,…,N-1,N) Where P i (u) is the B-spline curve, B N,i is the i-th basis function matrix of the N-th vertex, V i is the control point, T is the transpose, 0≤u≤1, N>3; According to the design parameters of the hyperbolic gas nozzle and the hyperbolic mathematical properties of supersonic gas dynamics, the characteristic line equation and compatibility equation of the flow are obtained, including: Where y is the y-axis coordinate, x is the x-axis coordinate, θ is the stream angle, μ is the Mach angle, M is the Mach number, γ is the specific heat ratio, and δ is the flow characteristic factor.

6. The method for designing a hypervelocity non-ideal gas nozzle according to any one of claims 1 to 3, characterized in that: According to the inviscid profile, the contraction section of the hypervelocity non-ideal gas nozzle is designed, including: Where y is the y-axis coordinate, t is the throat height, y i is the height of the inlet of the contraction section, x is the x-axis coordinate, L c is the length of the contraction section.

7. The method for designing a hypervelocity non-ideal gas nozzle according to any one of claims 1 to 3, characterized in that: According to the inviscid profile and the contraction section, the flow field of the hypervelocity non-ideal gas nozzle is obtained, including: shortening the downstream portion of the non-stick profile to obtain an updated non-stick profile; According to the updated inviscid profile and the contraction section, the flow field of the ultra-high-speed non-ideal gas nozzle is obtained.

8. A design device for a hypervelocity non-ideal gas nozzle, characterized in that: include: The design module is used to obtain the design parameters of the hypervelocity non-ideal gas nozzle and design the inviscid surface of the hypervelocity non-ideal gas nozzle using the characteristic line method; According to the inviscid profile, a contraction section of a hypervelocity non-ideal gas nozzle is designed; According to the inviscid surface and the contraction section, a flow field of a hypervelocity non-ideal gas nozzle is obtained; A simulation module, used to perform computational fluid dynamics simulation on the flow field using a computational fluid dynamics method to obtain a flow field simulation result; A calculation module for calculating the boundary layer thickness of a hypervelocity non-ideal gas nozzle using a computational fluid dynamics method; An iteration module, for redesigning the inviscid surface and the contraction section of the hypervelocity non-ideal gas nozzle according to the boundary layer thickness, and correcting the boundary layer thickness according to the flow field simulation result to obtain an updated flow field; Using a computational fluid dynamics method, a computational fluid dynamics simulation is performed on the updated flow field to obtain an updated flow field simulation result; The judgment module is used to output the current hypervelocity non-ideal gas nozzle when judging whether the updated flow field simulation result meets the preset requirements.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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