Design methods, devices, equipment and media for hypervelocity non-ideal gas nozzles

Abstract

The present application belongs to the field of engine nozzle technology and relates to a design method, device, equipment, and medium for a hypervelocity non-ideal gas nozzle. The method comprises: obtaining design parameters, designing the inviscid profile and contraction section of the hypervelocity non-ideal gas nozzle, and obtaining the flow field of the hypervelocity non-ideal gas nozzle; using computational fluid dynamics methods, performing computational fluid dynamics simulation on the flow field and calculating the boundary layer thickness of the hypervelocity non-ideal gas nozzle; based on the boundary layer thickness, redesigning the inviscid profile and contraction section of the hypervelocity non-ideal gas nozzle, and correcting the boundary layer thickness to obtain an updated flow field; using computational fluid dynamics methods, performing computational fluid dynamics simulation on the updated flow field to obtain an updated flow field simulation result; and outputting the current hypervelocity non-ideal gas nozzle when it is determined that the updated flow field simulation result meets preset requirements. The present application can accurately design a hypervelocity non-ideal gas nozzle.

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 over a century, wind tunnels have been essential testing facilities for aerospace technology. Wind tunnel testing of hypersonic vehicles demands even higher performance than supersonic vehicles. Generating high-enthalpy test flows in a hypersonic wind tunnel requires not only a high enough total temperature to produce significant non-ideal gas effects, but also a high level of flow uniformity to ensure the accuracy of the experimental data. Furthermore, the ideal gas state equations fail under non-ideal gas effects, and thick boundary layers cause the thin shear layer equations to fail. Conventional nozzle design methods face applicability issues and cannot achieve an ideal flow field. Therefore, compared to conventional subsonic or supersonic nozzle design, the design of hypersonic non-ideal gas nozzles is considerably more challenging.

[0003] Hypervelocity non-ideal gas nozzles are characterized by high total temperature, high total pressure, and ultra-high speed. The nozzle's convergence section, throat, and part of the supersonic section experience high-pressure flow, while the entire nozzle wall and the aforementioned areas experience high-temperature flow. For example, at standard atmospheric pressure, the vibrational energy of oxygen and nitrogen is excited at temperatures above 800K, and their specific heat capacity begins to vary significantly with temperature. Oxygen molecules ionize at temperatures above 2000K, and are essentially completely ionized into oxygen atoms above 4000K. The design operating conditions for hypervelocity non-ideal gas nozzles generally correspond to total temperatures of approximately 1500K at Mach 5, 4500K at Mach 10, and 8000K at Mach 20. These operating conditions far exceed standard atmospheric conditions, where the ideal gas assumption no longer applies and the non-ideal gas effect becomes pronounced.

[0004] At the same time, due to the effect of gas viscosity, the actual nozzle flow field differs from the inviscid flow field. Due to the presence of viscosity, the boundary layer thickness on the nozzle wall increases continuously with flow distance, causing the nozzle's effective area to 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 and is a small quantity compared to the nozzle's flow length. Therefore, the thin shear layer assumption holds true, and the boundary layer equations can be used to solve for the boundary layer displacement thickness, which is used for viscosity correction of the nozzle profile. However, for hypervelocity non-ideal gas nozzles, the boundary layer thickness increases significantly with increasing temperature. At this point, the thin shear layer assumption no longer holds, and the boundary layer equations become invalid, making it difficult to perform effective and accurate viscosity corrections.

[0005] The Sivells nozzle design method with a variable specific heat ratio is commonly used in the design of hypervelocity non-ideal gas nozzles. This method changes the traditional "outside-in" design approach, which involves designing the nozzle wall profile and internal flow field. Instead, the designer independently sets the axis Mach number distribution, and through inverse design (from the inside out), a nozzle profile with continuous curvature is obtained.

[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 (downstream of CD) 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 region. The temperature in this region is very high. The specific heat ratio γ2 adopts the average value of this region 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-eliminating 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 The empirical relationship 1.2 of the friction coefficient and the empirical relationship 1.3 of the shape factor are introduced to close the momentum integral relationship 1.1, and the reference enthalpy method is used to solve the boundary layer displacement thickness to achieve 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 Sivells method successfully avoids significant compression waves within the nozzle, achieving a uniform Mach number distribution at the nozzle exit and significantly improving flow field quality. To this day, the Sivells method remains the dominant design approach internationally.

[0016] However, the existing technologies including the Sivells method still have 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, and its derivation is 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, such as 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 hypersonic nozzle design and pointed 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 to address the above technical problems, so as to 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] Obtaining design parameters of a hypervelocity non-ideal gas nozzle and designing an inviscid profile of the hypervelocity non-ideal gas nozzle using a characteristic line method; designing a convergent section of the hypervelocity non-ideal gas nozzle based on the inviscid profile; and obtaining a flow field of the hypervelocity non-ideal gas nozzle based on the inviscid profile and the convergent 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] redesigning the inviscid surface and the contraction section of the hypervelocity non-ideal gas nozzle based on the boundary layer thickness, and correcting the boundary layer thickness based on the flow field simulation results to obtain an updated flow field; performing a computational fluid dynamics simulation on the updated flow field using a computational fluid dynamics method 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 flow field simulation results, including:

[0028] 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] Where Cp is the specific heat capacity, a0, a1, a2, a3, and 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] Where, δ * is the boundary layer displacement thickness, δ is the boundary layer thickness, 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, design parameters of a hypervelocity non-ideal gas nozzle are obtained, and a characteristic line method is used to design an inviscid profile of the hypervelocity non-ideal gas nozzle, 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 law of mass conservation; the throat area is corrected using the Eggers method to obtain a 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 conservation of mass, including:

[0044]

[0045] Where, 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, and γ is the gas specific heat ratio;

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

[0047]

[0048]

[0049] Where 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 exponential 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, the design of a convergence section of a hypervelocity non-ideal gas nozzle based on the inviscid surface includes:

[0058]

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

[0060] In one embodiment, the flow field of the hypervelocity non-ideal gas nozzle is obtained based on the inviscid surface and the contraction section, including:

[0061] truncating a 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 for obtaining design parameters of a hypervelocity non-ideal gas nozzle and designing an inviscid profile of the hypervelocity non-ideal gas nozzle using a characteristic line method; designing a contraction section of the hypervelocity non-ideal gas nozzle based on the inviscid profile; and obtaining a flow field of the hypervelocity non-ideal gas nozzle based on the inviscid profile and the contraction section;

[0065] A simulation module, configured 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 computational fluid dynamics methods;

[0067] an iterative module, configured 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 results 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 includes 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] Obtaining design parameters of a hypervelocity non-ideal gas nozzle and designing an inviscid profile of the hypervelocity non-ideal gas nozzle using a characteristic line method; designing a convergent section of the hypervelocity non-ideal gas nozzle based on the inviscid profile; and obtaining a flow field of the hypervelocity non-ideal gas nozzle based on the inviscid profile and the convergent 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] redesigning the inviscid surface and the contraction section of the hypervelocity non-ideal gas nozzle based on the boundary layer thickness, and correcting the boundary layer thickness based on the flow field simulation results to obtain an updated flow field; performing a computational fluid dynamics simulation on the updated flow field using a computational fluid dynamics method 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] Obtaining design parameters of a hypervelocity non-ideal gas nozzle and designing an inviscid profile of the hypervelocity non-ideal gas nozzle using a characteristic line method; designing a convergent section of the hypervelocity non-ideal gas nozzle based on the inviscid profile; and obtaining a flow field of the hypervelocity non-ideal gas nozzle based on the inviscid profile and the convergent 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] redesigning the inviscid surface and the contraction section of the hypervelocity non-ideal gas nozzle based on the boundary layer thickness, and correcting the boundary layer thickness based on the flow field simulation results to obtain an updated flow field; performing a computational fluid dynamics simulation on the updated flow field using a computational fluid dynamics method 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 above-mentioned design method, device, equipment and medium for ultra-high-speed non-ideal gas nozzles are designed to address the problem that conventional characteristic line and boundary layer correction methods are difficult to design ultra-high-speed non-ideal gas nozzles and difficult to obtain ideal flow fields. An iterative design method for ultra-high-speed non-ideal gas nozzles based on computational fluid dynamics and characteristic line method is designed. Specifically, the inviscid surface and contraction section of the nozzle are designed based on characteristic lines, the nozzle is shortened, and the nozzle flow field is calculated based on computational fluid dynamics, and then it is iterated. In this application, no single computational fluid dynamics optimization method lacking nozzle design theoretical guidance or a single characteristic line method that is no longer suitable for non-ideal gas effects is used. Instead, the nozzle is iteratively designed by combining computational fluid dynamics and characteristic line method, which has the computational advantages of calculating non-ideal gas effects and the theoretical advantages of designing nozzle wave systems. The nozzle flow field is simulated using 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 technical fields such as (hyper)sonic wind tunnels, engine nozzles, and aerodynamic experimental equipment. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0083] Figure 2 This is a diagram illustrating an application scenario of a design method for a hypervelocity non-ideal gas nozzle according to an embodiment;

[0084] Figure 3 1 is a flow chart of a method for designing a hypervelocity non-ideal gas nozzle according to one embodiment;

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

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

[0087] Figure 6 Schematic diagram of the nozzle computational domain mesh in one embodiment;

[0088] Figure 7 is the 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 according to one embodiment;

[0090] Figure 9 The profile of a Mach 10 hypervelocity non-ideal gas nozzle designed in one embodiment is shown;

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

[0092] Figure 11 FIG1 is a contour diagram of a Mach 10 hypervelocity non-ideal gas nozzle designed in one embodiment;

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

[0094] Figure 13 A structural block diagram of a design apparatus for a hypervelocity non-ideal gas nozzle according to one embodiment;

[0095] Figure 14 FIG. 1 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 this application more clearly understood, the present application is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely for explaining this application and are not intended to limit this application. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments in this application without creative work are within the scope of protection of this 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 various 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 terms "first," "second," and so on, used in this application are for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, features specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this application, "multiple groups" means at least two groups, such as two groups, three groups, and so on, unless otherwise specifically defined.

[0099] In this application, unless otherwise specified or limited, the terms "connect," "fix," etc. should be understood in a broad sense. For example, "fix" can mean a fixed connection, a detachable connection, or an integral connection; it can mean a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean internal communication between two elements or an interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in this application based on the 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 this field can implement it. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a 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 via a network. The terminal 202 may include but is not limited to various personal computers, laptops, smart phones, tablet computers, and portable wearable devices. The server 204 may be various portal websites, servers corresponding to the backend of the work system, etc.

[0102] This 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 example illustrates the terminal in the example, including:

[0103] Step 302: 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; design the contraction section of the hypervelocity non-ideal gas nozzle based on the inviscid surface; and obtain the flow field of the hypervelocity non-ideal gas nozzle based on the inviscid surface and the contraction section.

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

[0105] The design parameters of the hypervelocity non-ideal gas nozzle are obtained, and the throat area of ​​the ideal gas is obtained based on 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 scientific research or engineering needs, the design parameters of the hypervelocity non-ideal gas nozzle are obtained, and the design Mach number and exit height are obtained. Based on the law of conservation of mass, the relationship between the Mach number and area ratio of the ideal gas is obtained, and the throat area of ​​the ideal gas is obtained, including:

[0111]

[0112] Where 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, and 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 equation of state takes into account the effects of molecular size and intermolecular forces. The change in vibrational heat capacity is given by the Planck term. Using the Eggers method, the throat area is corrected to obtain the corrected throat area, which includes:

[0114] A * =A i * F(θ,T0,Ma) (1.6)

[0115]

[0116] Where 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 exponential with the natural number e as the base, B4, C4, and D4 are different correlation coefficients;

[0117] in:

[0118]

[0119]

[0120]

[0121] Where, γ i is the specific heat ratio under ideal gas conditions, Γ i 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 the coefficients of the gas vibration characteristic temperature θ, the specific values ​​of which are based on the existing technology.

[0122] For transonic flow at the nozzle throat, the gas dynamics equation, Equation 1.4, is parabolic and therefore difficult to solve directly. Traditional Foelsch and Cresci nozzle designs use a source flow assumption to simplify the flow near the throat, but the resulting error is unacceptable for high-Mach number nozzles.

[0123] Based on the design parameters of the hypervelocity non-ideal gas nozzle, this application adopts Hall's method to linearize the potential function equation through series expansion to obtain a transonic solution (how to obtain a transonic solution belongs to the prior art) and determine the axis starting point Mach number and 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 curve shape, T is the transpose, 0≤u≤1, N>3;

[0126] With the transonic solution and axial 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 spatial steps. 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 as follows 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, based on the inviscid surface, the contraction section of the hypervelocity non-ideal gas nozzle is designed using the fifth-power contraction section method. Its control equations include:

[0132]

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

[0134] Hypersonic non-ideal gas nozzles are typically very long, with their length varying depending on design methods and geometric parameters (such as the divergence angle and exit height). However, due to the characteristics of hypersonic flow, the streamwise component of the velocity is much greater than the normal component of the speed of sound within the streamline coordinate system, resulting in the nozzle's rhombus being much longer than its height. Given the high cost and thick boundary layer of nozzles, it is desirable to shorten the nozzle while ensuring flow uniformity. Flow uniformity can be assessed using computational fluid dynamics methods, and the truncation point is generally determined based on the engineering application.

[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 portion 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, where N 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 : Using a computational fluid dynamics method, 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 the 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 range of high enthalpy flow, and using NASA's piecewise polynomial fitting coefficients for specific heat capacity, the specific heat capacity of the hypervelocity non-ideal gas nozzle is obtained:

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

[0145] Where Cp is the specific heat capacity, a0, a1, a2, a3, and 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, where O i For the entrance, O e For export, A x is the axis of symmetry, P n It is the nozzle profile.

[0147] In this step, the flow uniformity of the truncated nozzle can be simulated using computational fluid dynamics (CFD) or other solvers. Furthermore, if the nozzle is used in a shock tunnel, chemical nonequilibrium effects can be accounted for using the Park dual-temperature model.

[0148] Step 306 : Calculate the boundary layer thickness of the hypervelocity non-ideal gas nozzle using a computational fluid dynamics method.

[0149] Specifically:

[0150]

[0151] Where, δ * is the boundary layer displacement thickness, δ is the boundary layer thickness (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: Redesign the inviscid surface and the contraction section of the hypervelocity non-ideal gas nozzle based on the boundary layer thickness, and correct the boundary layer thickness based on the flow field simulation results to obtain an updated flow field; use a computational fluid dynamics method to perform a 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 here.

[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: the boundary layer thickness of the hypervelocity non-ideal gas nozzle is recalculated; based on 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 updated flow field simulation result to obtain the next flow field; a computational fluid dynamics method is used to perform a computational fluid dynamics simulation on the next flow field to obtain the next flow field simulation result; the next flow field simulation result is judged until it meets the preset requirements, and the current hypervelocity non-ideal gas nozzle is output.

[0157] In this embodiment, the complete nozzle design architecture is as follows Figure 8 As shown. After entering 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 truncated. Then, the nozzle flow is calculated and simulated by computational fluid dynamics. Based on the computational fluid dynamics data, the boundary layer displacement thickness of the nozzle is calculated based on the displacement thickness definition. Based on the boundary layer displacement thickness distribution, the inviscid nozzle profile is again designed using the characteristic line method, and truncation and viscosity correction are performed. The new nozzle is then subjected to computational fluid dynamics calculations and simulations. If the flow field indicators do not meet the requirements, the boundary layer thickness is recalculated and iterated. If they meet the requirements, the design is completed. The design process uses Matlab, Visual Studio, Tecplot, and Fluent software. The entire design process is automated through the Microsoft Windows Command Prompt. The design process only requires the designer to submit the design requirements, and the computer will implement the nozzle iterative design.

[0158] The above-mentioned design method for a hypervelocity non-ideal gas nozzle addresses the problem that conventional characteristic line and boundary layer correction methods are difficult to design hypervelocity non-ideal gas nozzles and difficult to obtain ideal flow fields. An iterative design method for a hypervelocity non-ideal gas nozzle based on computational fluid dynamics and the characteristic line method is designed. Specifically, the inviscid profile and contraction section of the nozzle are designed based on the characteristic lines, the nozzle is shortened, and the nozzle flow field is calculated based on computational fluid dynamics, followed by cyclic iteration. In this application, the method does not solely adopt a computational fluid dynamics optimization method that lacks theoretical guidance for nozzle design, nor does it solely adopt a characteristic line method that is no longer suitable for non-ideal gas effects. Instead, the method combines computational fluid dynamics and the characteristic line method to iteratively design the nozzle, which has the computational advantages of calculating non-ideal gas effects and the theoretical advantages of designing nozzle wave systems. The nozzle flow field is simulated using 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 technical fields such as (hyper)sonic wind tunnels, engine nozzles, and aerodynamic experimental equipment.

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

[0161] The present application also provides a design device for an ultra-high-speed non-ideal gas nozzle, such as Figure 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 convergence section of the hypervelocity non-ideal gas nozzle is designed; based on the inviscid surface and the convergence 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 computational fluid dynamics methods;

[0165] an iterative 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 results to obtain an updated flow field; and performing 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 definitions of the hypervelocity non-ideal gas nozzle design apparatus can be found in the definitions of the hypervelocity non-ideal gas nozzle design method described above and will not be elaborated upon here. Each module in the aforementioned apparatus can be implemented in whole or in part via software, hardware, or a combination thereof. Each of these modules can be embedded in or independent of a processor in a computer device in hardware form, or stored in a computer device memory in software form, allowing the processor to call and execute the corresponding operations of each module.

[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: Figure 14As shown. The computer device includes a processor, a memory, a network interface, a display screen and an input device connected via a system bus. 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 via a network connection. When the computer program is executed by the processor, a method for designing 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 covering the display screen, or a key, trackball or touchpad provided on the computer device housing, or an external keyboard, touchpad or mouse.

[0169] Those skilled in the art will understand that Figure 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 shown in the figure, or combine certain components, or have a different component arrangement.

[0170] In one embodiment, a computer device is provided, including a memory and a processor. 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 will appreciate that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program. 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. By way of illustration and not limitation, RAM is available in various 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 can 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-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended 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; Designing a contraction section of a hypervelocity non-ideal gas nozzle based on the inviscid surface; and obtaining a flow field of the hypervelocity non-ideal gas nozzle based on the inviscid surface and the contraction section. Obtaining design parameters of a hypervelocity non-ideal gas nozzle and designing an inviscid surface of the hypervelocity non-ideal gas nozzle using a characteristic line method, including: obtaining the design parameters of the hypervelocity non-ideal gas nozzle and obtaining a throat area of ​​an ideal gas based on the law of mass conservation; correcting the throat area using the Eggers method to obtain a corrected throat area; obtaining a B-Spline curve based on the design parameters of the hypervelocity non-ideal gas nozzle; obtaining a characteristic line equation and a compatibility equation of the flow based on the design parameters of the hypervelocity non-ideal gas nozzle and the hyperbolic mathematical properties of supersonic gas dynamics; and obtaining the inviscid surface of the hypervelocity non-ideal gas nozzle based on the corrected throat area, the B-Spline curve, the characteristic line equation, and the compatibility equation. 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. redesigning the inviscid surface and the contraction section of the hypervelocity non-ideal gas nozzle based on the boundary layer thickness, and correcting the boundary layer thickness based on the flow field simulation results to obtain an updated flow field; performing a computational fluid dynamics simulation on the updated flow field using a computational fluid dynamics method 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 hypervelocity non-ideal gas nozzle according to claim 1, characterized in that: The flow field is simulated by computational fluid dynamics (CFD) to obtain flow field simulation results, including: 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, For pressure, is the universal gas constant, is the temperature, is the molar volume of the gas, and 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: Where, is the specific heat capacity, 、 、 、 、 is the fitting coefficient 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 hypervelocity non-ideal gas nozzle according to claim 2, characterized in that: Computational fluid dynamics methods are used to calculate the boundary layer thickness of hypervelocity non-ideal gas nozzles, including: Where, is the boundary layer displacement thickness, is the boundary layer thickness, is the density, For speed, is the density at the outer edge of the boundary layer, is the velocity at the outer edge of the boundary layer, 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: Obtain the design parameters of the hypervelocity non-ideal gas nozzle and, based on the law of mass conservation, obtain the throat area of ​​the ideal gas, including: Where, is the throat area, is the result under ideal gas conditions, is the nozzle outlet area, For the design Mach number, is the ratio of specific heats of gases; The throat area is corrected using the Eggers method to obtain a corrected throat area, including: Where, is the throat area under non-ideal gas conditions, is the correction function, is the vibration characteristic temperature of the gas, is the total temperature, is the stagnation density, is the molar volume constant, is the intermolecular force constant, is the gas constant, is the exponential of the natural number e, 、 、 are different correlation coefficients; According to the design parameters of the hypervelocity non-ideal gas nozzle, the B-Spline curve is obtained, including: Where, is the B-spline curve, For the N The vertex i basis function matrices, is the control point, is the transpose, ; 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, is the y-axis coordinate, is the x-axis coordinate, is the flow angle, is the Mach angle, is the Mach number, is the specific heat ratio, is the flow characteristic factor.

5. The method for designing a hypervelocity non-ideal gas nozzle according to any one of claims 1 to 3, characterized in that: Based on the inviscid surface, the convergence section of the hypervelocity non-ideal gas nozzle is designed, including: Where, is the y-axis coordinate, is the throat height, is the inlet height of the contraction section, is the x-axis coordinate, is the length of the contraction section.

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 surface and the contraction section, the flow field of the hypervelocity non-ideal gas nozzle is obtained, including: truncating a 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.

7. 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; Designing a contraction section of a hypervelocity non-ideal gas nozzle based on the inviscid surface; and obtaining a flow field of the hypervelocity non-ideal gas nozzle based on the inviscid surface and the contraction section. Obtaining design parameters of a hypervelocity non-ideal gas nozzle and designing an inviscid surface of the hypervelocity non-ideal gas nozzle using a characteristic line method, including: obtaining the design parameters of the hypervelocity non-ideal gas nozzle and obtaining a throat area of ​​an ideal gas based on the law of mass conservation; correcting the throat area using the Eggers method to obtain a corrected throat area; obtaining a B-Spline curve based on the design parameters of the hypervelocity non-ideal gas nozzle; obtaining a characteristic line equation and a compatibility equation of the flow based on the design parameters of the hypervelocity non-ideal gas nozzle and the hyperbolic mathematical properties of supersonic gas dynamics; and obtaining the inviscid surface of the hypervelocity non-ideal gas nozzle based on the corrected throat area, the B-Spline curve, the characteristic line equation, and the compatibility equation. A simulation module, configured 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 computational fluid dynamics methods; an iterative module, configured 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 results 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; 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.

8. 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 6 are implemented.

9. 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 6 are implemented.

Images