Currently, carbon-based materials are widely used as an ablative thermal protection for high-heat constructional elements in air and space en-gineering. In its turn, forecasting a change in shape of external surfaces of the specified elements with the course of time, which is determined by scorching of thermal protection, cannot be separated from the use of calcula-tion and theoretical procedures, which describe course of different phys-ico-chemical and mechanical processes associated with course of the considered event. Thereby, it is mandatory to approve such procedures through the re-sults of experi-mental studies, conducted in jets inside aerodynamic tunnels.
Among primary evidences of ablation of carbon-based materials is erosion (mass loss), which is usually observed in high-pressure gas flows. Meanwhile, it is required to carry out studies on large-scale models in the course of development tests, and that had de-termined the wide use of under-expanded jets of combustion gases of liquid-propellant rocket engines (LPE) for simulation of erosion of thermal protection.
Among the basic problems, encountering during solution of this kind of tasks, is calcu-lation of laminar-turbulent heat exchange in the conditions of gradient flow past blunt-ed point of the tested model by a diverging gas jet. This article is dedicated to the solu-tion of this problem and includes the modified version of semi-empirical model of ap-parent turbulent viscosity, approved by the results of experimental studies. This article shows that the use of this method makes it possible to specify significantly thermal con-di-tions of the model in comparison with the use of effective length method, which is used universally in practical work.
Горский В.В., Ковальский М.Г. Методика численного решения уравнений ламинарно-турбулентного пограничного слоя на осесимметричном затупленном теле в струе продуктов сгорания ЖРД. Математическое моделирование и численные методы, 2018, № 2, с. 96–108.
Testing thermal protection in jets of propulsion system combustion products is one of the priority types of its experimental development. The informational content of such trials depends to a large extent on the mathematical modeling of the processes taking place in the experiments under consideration. They include flow past a model made of ablative thermal protection, convective heat transfer and friction in the laminar-turbulent boundary layer formed on the model surface, ablation of thermal protection and change in the shape of the model. The article describes the mathematical modeling of the first of the above processes, associated with solving the complex problem of constructing the field of gas dynamic functions in the underexpanded high-pressure jet of the liquid rocket engine combustion products in a flooded space and the divergent jet flow around the model surface. The results of comparison of analytical results with experimental data are presented.
V.V. Gorsky, M.G. Kovalsky Techniques for numerical simulation flow around an axisymmetric blunt body in an underexpanded jet of liquid rocket engine combustion products. Маthematical Modeling and Coтputational Methods, 2017, №2 (14), pp. 65-80