C + + language-based calculation method for thrust characteristics of beveled nozzle of rocket engine

Abstract

The invention provides a C + + language-based calculation method for thrust characteristics of a beveled nozzle of a rocket engine. The C + + language-based calculation method comprises the steps of S1, constructing a C + + language development environment; s2, a C + + file is written, a beveled nozzle class is created, and the name of the beveled nozzle class is ScarfedNozzle; the oblique cutting nozzle type ScarfedNozzle comprises a member attribute and a member function; and S3, on the basis of the member attributes in the beveled nozzle type ScarfedNozzle obtained in the step S2, the calculation of the thrust characteristics of the beveled nozzle is completed by calling the member functions in the beveled nozzle type ScarfedNozzle obtained in the step S2. The device is convenient to use. A user only needs to input related parameters of the rocket engine beveled nozzle in a program written by a developer, and does not need to analyze and research a calculation process in detail or grasp computer programming knowledge.

Description

Technical Field

[0001] The present invention belongs to the technical field of rocket engines, relates to the thrust characteristics of an obliquely cut nozzle, and particularly relates to a method for calculating the thrust characteristics of an obliquely cut nozzle of a rocket engine based on the C++ language. Background Art

[0002] Rocket engines with beveled nozzles are usually used in technical fields such as inter-stage separation of multi-stage missiles, launch stages of short-range air defense missile weapons, and attitude control of tactical missiles. In addition, due to structural limitations, this design is often used in reverse nozzles for thrust termination.

[0003] The angled nozzles of this type of rocket engine typically feature a beveled section at the nozzle's expansion section. This beveled section causes the high-speed airflow flowing through it to expand and deflect, shifting the thrust direction by a certain angle and generating lateral force. Calculating the thrust characteristics of a rocket engine's angled nozzle primarily focuses on axial and tangential thrust.

[0004] Therefore, the design of rocket engines with such beveled nozzles urgently requires a mature and convenient calculation method that can quickly calculate the thrust characteristics of beveled nozzles and, in turn, calculate the missile's exterior trajectory. However, no such mature algorithm exists in the prior art for calculating the thrust characteristics of beveled nozzles. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a method for calculating the thrust characteristics of the oblique nozzle of a rocket engine based on the C++ language, so as to solve the technical problem that the efficiency of the calculation method in the existing technology needs to be further improved.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A method for calculating thrust characteristics of a rocket engine oblique nozzle based on C++ language, the method comprising the following steps:

[0008] Step S1: Building a C++ language development environment.

[0009] Step S2: Write a C++ file and create a scarfed nozzle class named ScarfedNozzle.

[0010] The scarfed nozzle class ScarfedNozzle includes member properties and member functions.

[0011] The member attributes include the nozzle bevel angle ψ, the nozzle expansion half angle α, the nozzle throat diameter dt, the y-axis radius a of the nozzle outlet bevel section, the rocket engine gas adiabatic index k, the rocket engine combustion chamber pressure Pc and the ambient pressure Pa.

[0012] The member functions include member function ac(), member function a0(), member function ε A0 (), member function k0(), member function δ(), member function f*(), member function fx(), member function fs() and constructor ScarfedNozzle().

[0013] Step S3, based on the member attributes in the ScarfedNozzle class obtained in step S2, the member functions in the ScarfedNozzle class obtained in step S2 are called to complete the calculation of the thrust characteristics of the scarfed nozzle.

[0014] Compared with the prior art, the present invention has the following technical effects:

[0015] (I) The present invention is easy to use. The user only needs to input the relevant parameters of the rocket engine bevel nozzle into the program written by the developer, without having to conduct detailed analysis and research on the calculation process, nor does it require computer programming knowledge.

[0016] (II) The present invention has a fast calculation speed. Since the program is developed in C++ language, which is characterized by its fast running speed, the entire calculation process is faster than other languages.

[0017] (III) The present invention is developed using the object-oriented concept of C++ language, with a clear process, clear code structure, and rigorous logical thinking, which facilitates developers' subsequent secondary development, debugging and maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a flow chart of the calculation method of the present invention.

[0019] Figure 2 This is a schematic diagram of a typical beveled nozzle structure.

[0020] Figure 3 This is a schematic diagram of the thrust characteristics of a typical oblique-cut nozzle.

[0021] The specific contents of the present invention are further explained in detail below with reference to the embodiments. DETAILED DESCRIPTION

[0022] It should be noted that, unless otherwise specified, all devices, software, functions and parameters in the present invention are those known in the prior art.

[0023] The present invention belongs to the field of rocket engine nozzle calculation, and specifically relates to a method for calculating the thrust characteristics of a rocket engine oblique nozzle based on C++ language. The thrust characteristics mainly include the calculation of the axial thrust and tangential thrust of the oblique nozzle. Figures 1 to 3 As shown, the method includes: first, creating a bevel nozzle class based on the C++ language. The member attributes of this class mainly include: nozzle bevel angle, nozzle expansion half angle, nozzle throat diameter, y-axis radius of the nozzle outlet bevel section, rocket engine gas adiabatic index, rocket engine combustion chamber pressure, ambient pressure, etc. The member functions of this class mainly include: nozzle outlet bevel section area calculation function, nozzle outlet bevel section projected area calculation function on the plane perpendicular to the nozzle axis, bevel nozzle expansion ratio calculation function, bevel nozzle thrust characteristic coefficient calculation function, bevel nozzle thrust deflection angle calculation function, bevel nozzle reaction force calculation function generated by the airflow expansion to the speed of sound during vacuum exhaust of the bevel nozzle, bevel nozzle axial thrust calculation function, bevel nozzle tangential thrust calculation function, constructor, etc. Specifically, the bevel nozzle thrust characteristic coefficient calculation process uses the "successive approximation method" and "bisection method" numerical methods, and the bevel nozzle thrust deflection angle calculation process uses the "successive approximation method" numerical method. The present invention adopts object-oriented programming ideas and compiles a computer program for the thrust characteristics of the rocket engine oblique nozzle based on the C++ language, so that designers can calculate the thrust characteristics of the oblique nozzle conveniently and quickly, thereby accelerating the development progress.

[0024] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent modifications made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0025] Example:

[0026] This embodiment provides a method for calculating the thrust characteristics of a rocket engine oblique nozzle based on C++ language, such as Figures 1 to 3 As shown, the method includes the following steps:

[0027] Step S1: Building a C++ language development environment.

[0028] Step S2: Write a C++ file and create a scarfed nozzle class named ScarfedNozzle.

[0029] The scarfed nozzle class ScarfedNozzle includes member properties and member functions.

[0030] The member attributes are the parameters of the rocket engine oblique nozzle, which include the nozzle oblique angle ψ, the nozzle expansion half angle α, the nozzle throat diameter dt, the y-axis radius a of the nozzle outlet oblique section, the rocket engine gas adiabatic index k, the rocket engine combustion chamber pressure Pc, and the ambient pressure Pa.

[0031] Member functions include member function ac(), member function a0(), member function ε A0 (), member function k0(), member function δ(), member function f*(), member function fx(), member function fs() and constructor ScarfedNozzle().

[0032] The member function ac() is used to calculate the nozzle outlet oblique cross-sectional area ac.

[0033] The member function a0() is used to calculate the projection area of ​​the oblique section of the nozzle outlet on the plane perpendicular to the nozzle axis.

[0034] Membership function ε A0 () is used to calculate the expansion ratio ε of the bevel-cut nozzle A0 ,

[0035] The member function k0() is used to calculate the thrust characteristic coefficient calculation function k0 of the oblique nozzle.

[0036] The member function δ() is used to calculate the thrust deflection angle δ of the oblique nozzle.

[0037] Member function f * () is used to calculate the reaction force f generated when the airflow expands to the speed of sound during vacuum exhaust of the bevel nozzle * .

[0038] The member function fx() is used to calculate the axial thrust fx of the oblique nozzle.

[0039] The member function fs() is used to calculate the tangential thrust fs of the oblique nozzle.

[0040] The constructor ScarfedNozzle() is used to initialize and assign values ​​to member properties.

[0041] Step S3, based on the member attributes in the ScarfedNozzle class obtained in step S2, the member functions in the ScarfedNozzle class obtained in step S2 are called to complete the calculation of the thrust characteristics of the scarfed nozzle.

[0042] In this embodiment, the gas flow in the oblique nozzle is in an under-expanded state.

[0043] In this embodiment, the thrust characteristics of the oblique nozzle include the axial thrust of the oblique nozzle and the tangential thrust of the oblique nozzle.

[0044] As a specific solution of this embodiment, the member function ac() is:

[0045]

[0046] As a specific solution of this embodiment, the member function a0() is:

[0047] a0=ac×sinψ。

[0048] As a specific solution of this embodiment, the membership function ε A0 ()for:

[0049]

[0050] As a specific solution of this embodiment, the member function k0() is:

[0051]

[0052] In the above formula, the value of k0 is difficult to obtain accurately using conventional methods. The numerical methods of "successive approximation method" and "bisection method" are adopted to solve it. That is: first assign an initial value to k0 and give a certain calculation step size step. When the design threshold is reached, switch to the "bisection method" to continue solving. When k0 meets the design error, the calculation ends.

[0053] As a specific solution of this embodiment, the member function δ() is:

[0054]

[0055] The value of δ in the above formula is difficult to obtain accurately using conventional methods. Since δ is taken as an angle, the solution domain is small, and the "stepwise approximation method" with a calculation step of 0.1° can be used for numerical solution.

[0056] As a specific solution of this embodiment, the member function f * ()for:

[0057] f * =C f* ×p C ×A t ;

[0058]

[0059] Where:

[0060] C f* It represents the thrust coefficient when the airflow expands to the speed of sound during vacuum exhaust of the bevel nozzle;

[0061] A t represents the throat area of ​​the beveled nozzle;

[0062] Γ represents the gas specific heat ratio function;

[0063] p e Indicates the outlet pressure of the bevel nozzle.

[0064] As a specific solution of this embodiment, the member function fx() is:

[0065] fx=k0×f * -a0×p a .

[0066] As a specific solution of this embodiment, the member function fs() is:

[0067] fs=fx×tanδ.

[0068] Figure 2 In Chinese, at means A t , represents the throat area of ​​the oblique nozzle; t represents the throat position of the oblique nozzle. Figure 3 In, F * That is, f*, which represents the thrust generated when the airflow expands to the speed of sound during vacuum exhaust of the bevel nozzle.

[0069] Application Example 1:

[0070] This application example provides a method for calculating the thrust characteristics of a rocket engine oblique nozzle based on the C++ language and the above embodiment.

[0071] The parameters of the bevel-cut nozzle in this application example are shown in Table 1.

[0072] Table 1 Parameters of the beveled nozzle in application example 1

[0073] Serial number parameter unit symbol Numerical 1 Nozzle bevel angle rad ψ 1.0472 2 Nozzle expansion half angle rad α 0.2618 3 Nozzle throat diameter mm dt 12 4 Y-axis radius of the nozzle outlet oblique section mm a 15.1 5 Rocket engine gas adiabatic index — k 1.22 6 Rocket engine combustion chamber pressure MPa PC 8.0 7 Ambient pressure MPa Pa 0.101325

[0074] The specific implementation steps of this application example are:

[0075] Step 1: Set up a C++ language development environment. Use Visual Studio code to write the program and use the open source software MinGW to compile the program.

[0076] Step 2. Create a new file in the VS code environment, name the header file sn01.h and the source file sn01.cpp.

[0077] Step 3. Declare the ScarfedNozzle class in the header file. The class contains the following member properties and member functions. The relevant code is as follows:

[0078]

[0079]

[0080] Step 4. In the source file sn01.cpp, implement the member function ScarfedNozzle(). The relevant code is as follows:

[0081]

[0082] Step 5. Implement the member function ac() in the source file sn01.cpp. The relevant code is as follows:

[0083] / / sn01.cpp

[0084] double ScarfedNozzle::ac()

[0085] {

[0086] return PAI*a*a*(tan(fai)-tan(alpha))*(sin(fai)+cos(fai)*tan(alpha))

[0087] / (tan(fai)*sqdt(1-tan(alpha)*tan(alpha) / (tan(fai)*tan(fai))));

[0088] }

[0089] Step 6. In the source file sn01.cpp, implement the member function a0(). The relevant code is as follows:

[0090] / / sn01.cpp

[0091] double ScarfedNozzle::a0()

[0092] {

[0093] return ac()*sin(fai);

[0094] }

[0095] Step 7. In the source file sn01.cpp, implement the member function yibusoa0(). The relevant code is as follows:

[0096] / / sn01.cpp

[0097] double ScarfedNozzle::yibusoa0()

[0098] {

[0099] return a0()*4 / (PAI*dt*dt);

[0100] }

[0101] Step 8. Implement the member function k0() in the source file sn01.cpp. The relevant code is as follows:

[0102] / / sn01.cpp

[0103] double ScarfedNozzle::k0()

[0104] {

[0105] double a0biat;

[0106] double ybsa0;

[0107] ybsa0=yibusoa0();

[0108] double cha;

[0109] double k0;

[0110] k0=1.0;

[0111] double wucha;

[0112] wucha=0.0001;

[0113] double step;

[0114] step=0.1;

[0115] double x1;

[0116] double x2;

[0117] do{

[0118] a0biat=pow(k-(k-1)*k0*(k0+sqdt(k0*k0-1.0)),1.0 / (1.0-k)) / (k0+sqdt(k0*k0-1.0));

[0119] cha=abs(ybsa0-a0biat);

[0120] if(cha <wucha)

[0121] {break;

[0122] }

[0123] else if(a0biat<ybsa0)

[0124] {

[0125] x1=k0;

[0126] k0=k0+step;

[0127] x2=k0;

[0128] }

[0129] else

[0130] {

[0131] do

[0132] {

[0133] k0=(x1+x2) / 2.0;

[0134] a0biat=pow(k-(k-1)*k0*(k0+sqdt(k0*k0-1.0)),1.0 / (1.0-k)) / (k0+

[0135] sqdt(k0*k0-1.0));

[0136] cha=abs(ybsa0-a0biat);

[0137] if(cha<wucha)

[0138] break;

[0139] else if(ybsa0<a0biat)

[0140] x2=k0;

[0141] else

[0142] {

[0143] x1=k0;

[0144] }

[0145] }while(true);

[0146] break;

[0147] }

[0148] }while(true);

[0149] return k0;

[0150] }

[0151] Step 9. In the source file sn01.cpp, implement the member function fxing(). The relevant code is as follows:

[0152] / / sn01.cpp

[0153] double ScarfedNozzle::fxing()

[0154] {

[0155] double kafang;

[0156] double cf_zhenkong;

[0157] double pcrbipc;

[0158] pcrbipc=pow((1+k) / 2,k / (1-k));

[0159] kafang=sqdt(k)*pow(2 / (k+1),(k+1) / (2*k-2));

[0160] cf_zhenkong=kafang*sqdt(2*k*pow(1-pcrbipc,(k-1) / k) / (k-1))+

[0161] pcrbipc;

[0162] return cf_zhenkong*pc*PAI*dt*dt / 4;

[0163] }

[0164] Step 10. Implement the member function drt() in the source file sn01.cpp. The relevant code is as follows:

[0165] / / sn01.cpp

[0166] double ScarfedNozzle::drt()

[0167] {

[0168] doubledrt;

[0169] drt=3.0;

[0170] double step;

[0171] step=0.1;

[0172] double para01;

[0173] double para02;

[0174] double para03;

[0175] double para04;

[0176] double k_0;

[0177] k_0=k0();

[0178] double result;

[0179] do

[0180] {

[0181] para01=k_0+sqdt(k_0*k_0-1.0);

[0182] para02=k_0 / cos(degree2rad(drt))+sqdt((k_0 / cos(degree2rad(drt)))*(k_0 / cos(degree2rad(drt)))-1.0);

[0183] para03=pow((k-(k-1.0)*k_0*para01) / (k-(k-1.0)*k_0*para02 / cos(degree2rad(drt))),1.0 / (k-1.0));

[0184] para04=sin(degree2rad(fai+drt)) / sin(degree2rad(fai));

[0185] result=para01 / para02*para03-para04;

[0186] if(result>0.0)

[0187] break;

[0188] else

[0189] {

[0190] drt=drt+step;

[0191] }

[0192] }while(true);

[0193] return drt;

[0194] }

[0195] Step 11. In the source file sn01.cpp, implement the member function fx(). The relevant code is as follows:

[0196] / / sn01.cpp

[0197] double ScarfedNozzle::fx()

[0198] {

[0199] return k0()*fxing()-a0()*pa;

[0200] }

[0201] Step 12. In the source file sn01.cpp, implement the member function fs(). The relevant code is as follows:

[0202] / / sn01.cpp

[0203] double ScarfedNozzle::fs()

[0204] {

[0205] return fx()*tan(drt());

[0206] }

[0207] Step 13. In the source file sn01.cpp, instantiate the ScarfedNozzle class and calculate the thrust characteristics. The relevant code is as follows:

[0208] / / sn01.cpp

[0209] int main()

[0210] {

[0211] double fai=1.0472;

[0212] double alpha=0.2618;

[0213] doubledt=12.0;

[0214] double a=15.1;

[0215] double k=1.22;

[0216] double pc=8.0;

[0217] double pa=0.101325;

[0218] double fx;

[0219] double fs;

[0220] ScarfedNozzle sn01=ScarfedNozzle(fai,alpha,dt,a,k,pc,pa);

[0221] fx = sn01.fx();

[0222] fs = sn01.fs();

[0223] return 0;

[0224] }

[0225] After the code runs, querying the values ​​of the variables fx and fs shows that the calculated axial thrust fx of the bevel-cut nozzle is 2996.45 N, and the calculated tangential thrust fs is 293.80 N.

[0226] Application Example 2:

[0227] This application example provides a method for calculating the thrust characteristics of a rocket engine oblique nozzle based on the C++ language and the above embodiment.

[0228] The parameters of the bevel-cut nozzle in this application example are shown in Table 2.

[0229] Table 2 Parameters of the bevel nozzle in application example 2

[0230] Serial number parameter unit symbol Numerical 1 Nozzle bevel angle rad ψ 0.9599 2 Nozzle expansion half angle rad α 0.3491 3 Nozzle throat diameter mm dt 18 4 Y-axis radius of the nozzle outlet oblique section mm a 23.1 5 Rocket engine gas adiabatic index — k 1.16 6 Rocket engine combustion chamber pressure MPa PC 12.0 7 Ambient pressure MPa Pa 0.101325

[0231] The specific implementation steps of this application example are basically the same as those in Application Example 1, with the only difference being Step 13.

[0232] In this application example, Step 13 is as follows:

[0233] Step 13. In the source file sn01.cpp, instantiate the ScarfedNozzle class and calculate the thrust characteristics. The relevant code is as follows:

[0234] / / sn01.cpp

[0235] int main()

[0236] {

[0237] double fai=0.9599;

[0238] double alpha=0.3491;

[0239] doubledt=18.0;

[0240] double a=23.1;

[0241] double k=1.16;

[0242] double pc=12.0;

[0243] double pa=0.101325;

[0244] double fx;

[0245] double fs;

[0246] ScarfedNozzle sn02=ScarfedNozzle(fai,alpha,dt,a,k,pc,pa);

[0247] fx = sn02.fx();

[0248] fs = sn02.fs();

[0249] return 0;

[0250] }

[0251] After the code runs, querying the values ​​of the variables fx and fs shows that the calculated axial thrust fx of the bevel-cut nozzle is 11466.2N, and the calculated tangential thrust fs is 1550.3N.

Claims

1. A method for calculating the thrust characteristics of a rocket engine oblique nozzle based on the C++ language, the method comprising the following steps: Step S1, building a C++ language development environment; Its characteristics are: Step S2, write a C++ file and create a scarfed nozzle class named ScarfedNozzle; The ScarfedNozzle class includes member attributes and member functions; The member attributes include the nozzle bevel angle ψ, the nozzle expansion half angle α, the nozzle throat diameter dt, the y-axis radius a of the nozzle outlet bevel section, the rocket engine gas adiabatic index k, the rocket engine combustion chamber pressure Pc, and the ambient pressure Pa; The member functions include member function ac(), member function a0(), member function ε A0 (), member function k0(), member function δ(), member function f*(), member function fx(), member function fs() and constructor ScarfedNozzle(); The member function ac() is used to calculate the nozzle outlet oblique cross-sectional area ac; The member function a0() is used to calculate the projection area of ​​the nozzle outlet oblique cross section on the plane perpendicular to the nozzle axis. The membership function ε A0 () is used to calculate the expansion ratio ε of the bevel-cut nozzle A0 , The member function k0() is used to calculate the thrust characteristic coefficient calculation function k0 of the oblique nozzle; The member function δ() is used to calculate the thrust deflection angle δ of the oblique nozzle; The member function f * () is used to calculate the reaction force f generated when the airflow expands to the speed of sound during vacuum exhaust of the bevel nozzle * ; The member function fx() is used to calculate the axial thrust fx of the bevel-cut nozzle; The member function fs() is used to calculate the tangential thrust fs of the oblique nozzle; The constructor ScarfedNozzle() is used to initialize and assign values ​​to the member attributes; Step S3, based on the member attributes in the ScarfedNozzle class obtained in step S2, the member functions in the ScarfedNozzle class obtained in step S2 are called to complete the calculation of the thrust characteristics of the scarfed nozzle.

2. The method for calculating the thrust characteristics of a rocket engine oblique nozzle based on C++ language according to claim 1, characterized in that: The member function ac() is:

3. The method for calculating the thrust characteristics of a rocket engine oblique nozzle based on C++ language according to claim 2, characterized in that: The member function a0() is: a0=ac×sinψ。 4. The method for calculating the thrust characteristics of a rocket engine oblique nozzle based on C++ language as claimed in claim 3, characterized in that: The membership function ε A0 ()for:

5. The method for calculating the thrust characteristics of a rocket engine oblique nozzle based on C++ language according to claim 4, characterized in that: The member function k0() is:

6. The method for calculating the thrust characteristics of a rocket engine oblique nozzle based on C++ language according to claim 5, characterized in that: The member function δ() is:

7. The method for calculating thrust characteristics of a rocket engine oblique nozzle based on C++ language according to claim 6, characterized in that: The member function f * ()for: f * =C f* ×p C ×A t ; Where: C f* It represents the thrust coefficient when the airflow expands to the speed of sound during vacuum exhaust of the bevel nozzle; A t represents the throat area of ​​the beveled nozzle; Γ represents the gas specific heat ratio function; p e Indicates the outlet pressure of the bevel nozzle.

8. The method for calculating thrust characteristics of a rocket engine oblique nozzle based on C++ language according to claim 7, characterized in that: The member function fx() is: fx=k0×f * -a0×p a 。 9. The method for calculating thrust characteristics of a rocket engine oblique nozzle based on C++ language according to claim 8, characterized in that: The member function fs() is: fs=fx×tanδ.

10. The method for calculating thrust characteristics of a rocket engine oblique nozzle based on C++ language according to claim 1, characterized in that: The gas flow in the obliquely cut nozzle is in an under-expanded state; the thrust characteristics of the obliquely cut nozzle include the obliquely cut nozzle axial thrust and the obliquely cut nozzle tangential thrust.

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