CN110457804B - Numerical method for predicting jet flow noise of single-nozzle carrier rocket - Google Patents
Numerical method for predicting jet flow noise of single-nozzle carrier rocket Download PDFInfo
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Abstract
The invention discloses a numerical method for predicting jet noise of a single-nozzle carrier rocket, which comprises the steps of firstly, establishing a single-nozzle carrier rocket three-dimensional model, and carrying out grid division on the single-nozzle carrier rocket three-dimensional model by using a partition structured grid method; thirdly, calculating a steady-state flow field of the gas jet of the single-jet-pipe carrier rocket to obtain initial sound field information; obtaining initial sound field information from a steady-state flow field, and reconstructing a turbulent flow pulse signal by adopting a nonlinear disturbance equation; and finally, collecting far-field receiving point noise information based on an FW-H equation of an acoustic comparison method, and outputting a frequency spectrum curve of a noise receiving point. The invention reduces the number of grids and improves the calculation efficiency while ensuring the calculation accuracy.
Description
Technical Field
The invention belongs to the field of interdisciplines of hydrodynamics and acoustics, and particularly relates to a numerical method for predicting jet noise of a single-nozzle carrier rocket.
Background
The space carrier rocket generally comprises a power device, a rocket body structure, a control system and other parts. The structure generally comprises a head, a head fairing, an oxidant storage tank, a fuel (combustion agent) storage tank, an instrument cabin, a stage section, an engine thrust structure, a tail cabin and the like, and a separation connecting device is arranged at a part needing to be separated. The fairing is used for protecting the satellite and other effective loads so as to prevent the satellite from being influenced by harmful environments such as aerodynamic force, pneumatic heating, sound vibration and the like, and is an important component of the carrier rocket. When the rocket is launched and lifted, the liquid propellant is combusted after the engine is ignited, high-temperature and high-speed gas is generated through the Laval nozzle, and simultaneously the high-temperature and high-speed gas interacts with static air to induce jet noise. During rocket launching tests, particularly high-thrust heavy carrier rockets, high-speed incandescent jet flow discharged from a high-pressure engine induces strong noise to be transmitted to a remote place through a flow guide device, and due to the fact that sound waves generate strong sound load on carrier rocket bodies, interference influence is caused on spacecrafts or various precise instruments in cabin sections, and the jet flow noise environmental control problem of a new generation of high-thrust carrier rocket launching system is more and more prominent. Rocket jet noise can damage artificial satellites and other effective loads in the fairing and control devices in the stage section, damage the launching safety of the rocket, and cause failure of rocket launching in severe cases.
The single-nozzle rocket-borne jet noise prediction is carried out, a frequency spectrum curve is obtained, and a foundation is provided for instrument equipment and a manned spacecraft to provide better external environment excitation and further carry out noise prediction and noise control technology application. West, Jeff in the Development of Modeling Capabilities for Launch Pad analytics and Ignition Transient Environment Prediction, used a 5 hundred million grid, 3000 processors to predict the noise of an Ares-I Launch vehicle. With the increasing demand for high-thrust rockets, the launching environment is increasingly severe, and the rocket noise calculation domain is enlarged, so that a numerical simulation method for predicting the rocket jet noise, which can reduce the number of grids and improve the calculation efficiency while ensuring the calculation accuracy, is urgently needed.
Disclosure of Invention
The invention aims to provide a numerical method for predicting jet noise of a single-nozzle carrier rocket, and aims to solve the problem that the jet noise of the single-nozzle carrier rocket is long in calculation time period.
The technical solution for realizing the purpose of the invention is as follows: a numerical method for predicting jet flow noise of a single-nozzle carrier rocket comprises the following steps:
the single-nozzle rocket three-dimensional model comprises a rocket, nozzles, the ground and a diversion trench; and (3) keeping the parameters of the three-dimensional model consistent with those of the actual engineering, and performing 1: 1 geometric modeling.
Step 2, carrying out grid division on the single-nozzle rocket three-dimensional model by using a partition structured grid method:
performing sub-domain block division processing on the single-nozzle rocket carrying three-dimensional model, and dividing the total calculation domain into two sub-domains: one subdomain is an above-ground region I and comprises rockets, nozzles and outer domains of the rockets and the nozzles; the other sub-domain is a ground surface region II and comprises a diversion trench inner domain;
wherein q' is a transient disturbance term,
as a transient average term, F i ' is a non-viscous disturbance term,
is a non-viscous mean term, (F) i υ ) ' is a viscous disturbance term,
is a viscosity average term, x i The components of each coordinate axis of the x axis, the y axis and the z axis;
wherein the values of i, j and k are 1, 2 and 3, wherein 1, 2 and 3 respectively represent the directions of an x axis, a y axis and a z axis; is rocket fuel gas density; u. u i ,u j ,u k The speeds along the directions of the x axis, the y axis and the z axis respectively; p is the pressure intensity; e is unit volume energy; delta ij Is a kronecker function; tau is ki In order to be a term of the shear stress,
means averaging a physical quantity,' means a disturbance term;
and 5, collecting far-field receiving point noise information based on an FW-H equation of an acoustic comparison method, and outputting a frequency spectrum curve of a noise receiving point.
Compared with the prior art, the invention has the remarkable advantages that:
(1) the problems of large whole flow field area, large grid scale and low calculation efficiency of the single-nozzle carrier rocket are effectively solved, and the problem of predicting the jet flow noise calculation accuracy of the single-nozzle carrier rocket is solved.
(2) The adopted nonlinear disturbance equation has low diffusion, and can effectively capture the noise of the sub-grid scale calculation; thus, good numerical accuracy can be achieved with relatively few meshes compared to other turbulence models.
(3) And a nonlinear disturbance equation is adopted, so that the calculation time of the jet flow noise of the single-nozzle rocket is reduced.
Drawings
FIG. 1 is a flow chart of a numerical method for predicting jet noise of a single-nozzle carrier rocket according to the present invention.
FIG. 2 is a three-dimensional model diagram of a rocket carried by a single nozzle, defining the circle center position of the nozzle outlet as the origin of coordinates, and rocket noise receiving points S1, S2 and S3 are located right above the nozzle outlet and are respectively spaced from the nozzle outlet by 46m, 34m and 22 m.
FIG. 3 is a cross-sectional view of a three-dimensional model of a single nozzle carrier rocket according to the present invention.
FIG. 4 is a partitioned structured grid diagram of a single nozzle carrier rocket according to the present invention.
Fig. 5 is a frequency plot of the single nozzle airborne rocket noise receiving point S1 of the present invention, wherein the abscissa F represents frequency and the ordinate SPL represents sound pressure level.
Fig. 6 is a frequency plot of a single nozzle carrier rocket noise receiving point S2, wherein the abscissa F represents frequency and the ordinate SPL represents sound pressure level.
Fig. 7 is a frequency plot of a single nozzle carrier rocket noise receiving point S3, wherein the abscissa F represents frequency and the ordinate SPL represents sound pressure level.
Detailed Description
The present invention is described in further detail below with reference to the attached drawing figures.
With reference to fig. 1, the numerical method for predicting the jet noise of a single-nozzle carrier rocket according to the present invention includes the following steps:
with reference to fig. 2, a single-nozzle rocket three-dimensional model is established through SolidWorks software, and the single-nozzle rocket three-dimensional model comprises a rocket 1, nozzles 2, the ground 3 and a diversion trench 4; and (3) keeping the parameters of the three-dimensional model consistent with those of the actual engineering, and performing 1: 1 geometric modeling.
Step 2, carrying out grid division on the single-nozzle rocket three-dimensional model by using a partition structured grid method:
with reference to fig. 4, the sub-domain blocking processing is performed on the single-nozzle rocket carrying three-dimensional model, and the total calculation domain is divided into two sub-domains: one subdomain is an above-ground region I and comprises a rocket 1, a nozzle 2 and external domains thereof; the other sub-region is a ground surface region II and comprises a region in the diversion trench 3.
step 3-1, making the following basic assumptions on rocket fuel gas: (1) the fuel gas meets the requirement of a continuous medium; (2) the fuel gas is a compressible pure gas phase medium; (3) no chemical reaction occurs inside the fuel gas; (4) the gas satisfies the ideal gas equation of state.
Step 3-2, adopting an Euler description method, assuming that a control body V is taken at a certain fixed position in a flow field at a certain time t under a Cartesian coordinate system, and taking an arbitrary scalar phi in the control body V, the scalar meets a conservation equation
In the formula, rho is the density of the rocket fuel gas,
is a velocity vector. First term on the left side of equation
Is a transient term representing the rate of change of a scalar phi over time; second item on the left
Is a convection term;the first term on the right side of the equation is a diffusion term, wherein gamma is a diffusion term coefficient and is different due to different conservation equation forms; second item on the right side S φ Is an equation source term that varies according to conservation equations.
3-3, calculating a rocket gas jet steady-state flow field by using an anisotropic two-equation Cubick-epsilon turbulence model to obtain initial sound field information:
wherein, U j Is the average velocity component (j ═ 1, 2, 3) in a Cartesian coordinate system, x j Is the corresponding coordinate component in Cartesian rectangular coordinate system, rho is the rocket gas density, mu is the viscosity coefficient, mu t Is the vortex viscosity coefficient, k is the turbulence kinetic energy, epsilon is the dissipation ratio of the turbulence kinetic energy, P k A production term for the average velocity gradient induced turbulence energy k, E a user-defined source term,
for turbulent stress tensor, U i,j Is U i At the coordinate x j Derivative of direction, T t For the time scale of turbulence, the constant term σ k ＝1.0，σ ε ＝1.3，C ε1 ＝1.44，C ε2 ＝1.92。
wherein q' is a transient disturbance term,
as a transient average term, F i ' is a non-viscous disturbance term,
is a non-viscous mean term, (F) i υ ) ' is a viscous disturbance term,
is a viscosity average term, x i Are components of the coordinate axes x, y and z.
Wherein the values of i, j and k are 1, 2 and 3, wherein 1, 2 and 3 respectively represent the directions of an x axis, a y axis and a z axis; density of rocket fuel gas; u. of i ,u j ,u k The speeds along the directions of the x axis, the y axis and the z axis respectively; p is the pressure; e is unit volume energy; delta. for the preparation of a coating ij Is a kronecker function; tau is ki In order to be a term of the shear stress,
means averaging some physical quantity, and' means perturbation term.
Step 5, collecting far-field receiving point noise information based on an FW-H equation of an acoustic comparison method, and outputting a frequency spectrum curve of a noise receiving point:
step 5-1, obtaining far-field receiving point noise based on an FW-H equation of an acoustic comparison method, and outputting a frequency spectrum curve of the noise receiving point:
in 1969, based on the Curle equation, in consideration of the influence of the solid wall on sound, Ffowcs Williams and Hawking apply the generalized function theory to obtain the FW-H equation:
in the formula, a 0 Is far field sound velocity, p 'is observation point sound pressure, x' i Is a component in the direction of coordinate i (i ═ 1, 2, 3), T ij Is the Leitchl (Lighthill) stress tensor, n j Is a unit out normal vector, u 'on the control surface' i Is x' i Directional fluid velocity component, u n And v n Respectively, a fluid velocity component perpendicular to the integration plane and an integration plane movement velocity component, p 0 The mean value of the density of the fluid when the fluid is not disturbed, and rho is the density of the rocket fuel gas; p ij δ (f) is the Dirac delta function for the stress tensor; h (f) is the Hervesseld (Heaviside) function.
And 5-2, performing Fourier transform on a sound source surface for capturing sound source information, and obtaining a frequency curve of a noise receiving point of a noise result after calculation, thereby providing a good external environment excitation for instruments and equipment and manned spacecraft, and further providing a basis for further developing noise prediction and noise control technology application.
Examples
With reference to fig. 1, a numerical method for predicting jet noise of a single nozzle rocket includes the following steps according to the above specific embodiment:
with reference to fig. 2, the three-dimensional model includes a rocket 1, a nozzle 2 and a guiding gutter 3, and is performed with the actual engineering multi-nozzle rocket by the following steps: 1 geometric modeling.
Step 2, carrying out mesh division on the three-dimensional model by using a partition structured mesh method;
and (3) carrying out partition structured grid processing on the geometric model by combining with the graph 3, and dividing the grid of the single nozzle rocket with the diversion trench, wherein the total number of the grids is about 370 ten thousand finally.
total pressure in the combustion chamber: 1.75*10 7 Total temperature of Pa combustion chamber: 3800k the outer boundary of the computational domain is assigned an atmospheric condition and satisfies characteristic boundary conditions, i.e., the outer boundary satisfies a no-reflection condition, and the jet tube and other solid walls are assigned an adiabatic no-slip wall condition.
and 5, obtaining far-field receiving point noise based on an FW-H equation of an acoustic comparison method, and outputting a frequency spectrum curve of the noise receiving point.
The numerical calculation method for predicting the jet noise of the single-nozzle carrier rocket takes ten days to output a frequency curve of a noise monitoring point on the axis of a nozzle under the condition of parallel calculation by using 40 CPUs, wherein a frequency curve of a single-nozzle rocket noise receiving point S1 is shown in FIG. 5, a frequency curve of a single-nozzle rocket noise receiving point S2 is shown in FIG. 6, and a frequency curve of a single-nozzle rocket noise receiving point S3 is shown in FIG. 7. The method can reduce the number of grids and improve the calculation efficiency while ensuring the calculation accuracy, and the calculation result can provide theoretical and technical guidance for predicting the rocket noise.
Claims (3)
1. A numerical method for predicting jet noise of a single-nozzle carrier rocket is characterized by comprising the following steps:
step 1, establishing a single-nozzle carrier rocket three-dimensional model:
the single-nozzle rocket carrying three-dimensional model comprises a rocket (1), nozzles (2), the ground (3) and a diversion trench (4); and (3) keeping the parameters of the three-dimensional model consistent with those of the actual engineering, and performing 1: 1, equal ratio modeling;
step 2, carrying out grid division on the single-nozzle carrier rocket three-dimensional model by using a partition structured grid method:
performing sub-domain block division processing on the single-nozzle rocket carrying three-dimensional model, and dividing the total calculation domain into two sub-domains: one subdomain is an area I above the ground, and comprises a rocket (1), a jet pipe (2) and outer domains thereof; the other sub-domain is a ground surface region II and comprises an inner domain of the diversion trench (4);
step 3, calculating a steady-state flow field of the fuel gas jet of the single-jet-pipe carrier rocket to obtain initial sound field information;
step 4, obtaining initial sound field information by using the step 3, and reconstructing turbulent flow pulse signals by using a nonlinear disturbance equation;
wherein q' is a transient disturbance term,
as a transient average term, F i ' is a non-viscous disturbance term,
is a non-viscous mean term, (F) i υ ) ' is a viscous disturbance term,
is a viscosity average term, x i The components of each coordinate axis of the x axis, the y axis and the z axis;
wherein the values of i, j and k are 1, 2 and 3, wherein 1, 2 and 3 respectively represent the directions of an x axis, a y axis and a z axis; rho is the rocket fuel gas density; u. of i ,u j ,u k The speeds along the directions of the x axis, the y axis and the z axis respectively; p is the pressure intensity; e is unit volume energy; delta ij Is a kronecker function; tau is ki In order to be a term of the shear stress,
means for averaging a physical quantity, and means for perturbing a physical quantity;
and 5, collecting far-field receiving point noise information based on an FW-H equation of an acoustic comparison method, and outputting a frequency spectrum curve of a noise receiving point.
2. The numerical method for predicting jet noise of a single-nozzle carrier rocket according to claim 1, wherein in step 3, a steady-state flow field of the single-nozzle carrier rocket gas jet is calculated to obtain initial sound field information:
step 3-1, making the following basic assumptions on rocket fuel gas: 1) the fuel gas meets the requirement of a continuous medium; 2) the fuel gas is a compressible pure gas phase medium; 3) no chemical reaction occurs inside the fuel gas; 4) the fuel gas meets an ideal gas state equation;
step 3-2, adopting an Euler description method, assuming that a control body V is taken at a certain fixed position in a flow field at a certain time t under a Cartesian coordinate system, and taking an arbitrary scalar phi in the control body V, the scalar meets a conservation equation
Wherein rho is the density of the rocket fuel gas,
is a velocity vector; first term on the left side of equation
Is a transient term representing the rate of change of a scalar phi over time; second item on the left
Is a convection term; the first term on the right side of the equation is a diffusion term, wherein gamma is a diffusion term coefficient and is different due to different conservation equation forms; second item on the right side S φ Is an equation source term which changes according to different conservation equations;
3-3, calculating a rocket gas jet steady-state flow field by using an anisotropic two-equation Cubic k-epsilon turbulence model to obtain initial sound field information:
wherein, U j Is the average velocity component in a Cartesian coordinate system, where j is 1, 2, 3, x j Is the corresponding coordinate component in Cartesian rectangular coordinate system, rho is the rocket gas density, mu is the viscosity coefficient, mu t Is the vortex viscosity coefficient, k is the turbulence kinetic energy, epsilon is the dissipation ratio of the turbulence kinetic energy, P k The generation term for the average velocity gradient induced turbulence energy k, E is a user-defined source term,
for turbulent stress tensor, U i,j Is U i At the coordinate x j Derivative of direction, T t For the time scale of turbulence, the constant term σ k ＝1.0，σ ε ＝1.3，C ε1 ＝1.44，C ε2 ＝1.92。
3. The numerical method for predicting jet noise of a single-nozzle launch vehicle according to claim 1, wherein step 5, based on FW-H equation of acoustic analogy, collects noise information of far-field receiving points, and outputs a spectrum curve of the noise receiving points, specifically as follows:
step 5-1, obtaining far-field receiving point noise based on an FW-H equation of an acoustic comparison method, and outputting a frequency spectrum curve of the noise receiving point:
on the basis of a Curle equation, considering the influence of a solid wall surface on sound, Ffowcs Williams and Hawking apply a generalized function theory to obtain an FW-H equation:
in the formula, a 0 Is far field sound velocity, p 'is observation point sound pressure, x' i Is a component in the direction of coordinate i, where i is 1, 2, 3, T ij Is the Lighthill stress tensor, n j Is a unit out normal vector, u 'on the control surface' i Is x' i Directional fluid velocity component, u n And v n Respectively, a fluid velocity component perpendicular to the integration plane and an integration plane moving velocity component, rho 0 The mean value of the density of the fluid when the fluid is not disturbed, and rho is the density of the rocket fuel gas; p ij δ (f) is the Dirac delta function for the stress tensor; h (f) is a Heaviside function;
and 5-2, performing Fourier transform on the sound source surface for capturing the sound source information, and obtaining a frequency curve of the noise receiving point of the noise result after calculation.
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