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COMPUTER HYDROMECHANICS, 2024
IX International Scientific & Practical Conference "Computer Hydromechanics"
HYDRODYNAMICS AND ACOUSTICS
2022 ◊ Volume 2 (92) ◊ Issue 3 ◊ p. 229-255
I. V. Vovk*, V. S. Malyuga*
* Institute of Hydromechanics of NAS of Ukraine, Kyiv, Ukraine
Evaluation of turbulent pressure pulsations in the boundary layer of the rocket
Gidrodin. akust. 2022, 2(3):229-255
TEXT LANGUAGE: Ukrainian
ABSTRACT
The article develops a method of numerical simulation of the aerodynamic flow around the rocket in trans- and supersonic flight modes. Numerical calculations of the characteristics of such a flow are carried out. In particular, estimates of the distribution of near-wall pressure pulsations acting on the rocket head were obtained. The developed algorithm of numerical simulation belongs to the class of hybrid semi-empirical methods. This algorithm divides the problem into two steps. In the first step, the aerodynamics of trans- and supersonic airflow around the rocket is numerically simulated, and the characteristics of the turbulent boundary layer are calculated, such as the boundary layer thickness, the tangential stresses on the wall, the dynamic velocity, Reynolds number in the boundary layer, the air density on the rocket fairing wall. In the second step, the analysis of the spectral densities of the root-mean-square values of the pressure pulsations is performed on the basis of semi-empirical relations. When simulating the supersonic flow, the Reynolds-averaged equations of compressible fluid supplemented by the continuity equation are numerically solved. When modeling turbulence, the standard $k$-$\varepsilon$ model is used. The paper pays special attention to the analysis of the characteristics of the turbulent boundary layer. For this purpose, a very detailed mesh is built near the surface of the fairing. The governing equations are solved by the finite volume method. The calculated characteristics of the boundary layer are used to analyze the spectral densities of the root-mean-square values of pressure pulsations. The distribution of the turbulent pulsation levels in the third-octave frequency range was calculated using universal semi-empirical dependencies. The proposed technique is implemented using the open-source toolbox OpenFOAM. OpenFOAM offers sonicFoam and rhoCentralFoam as solvers. The solvers are designed to model the problems of trans- and supersonic laminar or turbulent compressible flow. These solvers differ from one another by basic algorithms. SonicFoam is based on a pressure-based algorithm, and rhoCentralFoam is based on a density-based algorithm. SonicFoam solver was used in this work. The problem was considered within the framework of the ideal gas model. The developed method uses the technique of parallel calculations. The parallelization of calculations was performed on the basis of the MPI protocol and the principle of geometric parallelism. The calculations were performed on a cluster supercomputer of the Institute of Cybernetics of the National Academy of Sciences of Ukraine.
KEY WORDS
boundary layer, turbulent pulsations, supersonic flow around a rocket, OpenFOAM