Heat fluxes at a cylindrical copper model surface in supersonic underexpanded jets of dissociated air for experimental conditions on the induction plasma torch VGU-4 with different models of boundary conditions at the surface
The objective of this work is to perform a computational study of heat transfer between copper water-cooled models with a flat end in the nose section with supersonic jets of dissociated air for conditions realized in experiments on the VGU-4 RF plasma torch when working with conical nozzles with outlet section diameters of 30, 40 and 50 mm in the range of air flow rates supplied to the discharge channel of 2.4 – 4.8 g/s and to compare these calculated data with experimental values. For the experimental conditions, a numerical simulation of the flow around the models was performed within the framework of the Navier-Stokes equations for multicomponent nonequilibrium dissociated air taking into account chemical reactions in the flow and on the cold surface for various boundary conditions on their surfaces (the Goulard model and the model of stage-by-stage heterogeneous kinetics of the interaction of dissociated air with the copper surface). Both models use one free parameter, the variation of which allows obtaining heat flux densities in the vicinity of the stagnation point identical to the experimental values, although in the second model this parameter, unlike the first, has a clear physical meaning. From the calculations, the values of these parameters were obtained for two copper water-cooled cylindrical models with a diameter of 20 mm and 30 mm with a flat end in the nose section at different distances between the front stagnation point of the models and the nozzle section, which varied in the range from 25 mm to 50 mm.
Тепловые потоки к поверхности цилиндрической модели из меди в сверхзвуковых недорасширенных струях диссоциированного воздуха для условий экспериментов на индукционном плазмотроне ВГУ-4 с различными моделями граничных условий на поверхности
Цель данной работы заключается в расчетном исследовании теплообмена медных водоохлаждаемых моделей с плоским торцом в носовой части со сверхзвуковыми струями диссоциированного воздуха для условий, реализуемых в экспериментах на ВЧ-плазмотроне ВГУ-4 при работе с коническими соплами с диаметрами выходных сечений 30, 40 и 50 мм в диапазоне расхода подаваемого воздуха в разрядный канал 2.4 – 4.8 г/с и в сравнении этих расчетных данных с экспериментальными значениями. Для условий экспериментов выполнено численное моделирование обтекания моделей в рамках уравнений Навье-Стокса для многокомпонентного неравновесно диссоциированного воздуха с учетом химических реакций в потоке и на холодной поверхности для различных граничных условий на их поверхностях (модели Гуларда и модели постадийной гетерогенной кинетики взаимодействия диссоциированного воздуха с поверхностью меди). В обеих моделях используется по одному свободному параметру, вариация которых позволяет получить плотности тепловых потоков в окрестности точки торможения одинаковые с экспериментальными значениями, хотя во второй модели этот параметр, в отличие от первой, имеет ясный физический смысл. Из расчетов получены значения этих параметров для двух медных водоохлаждаемых цилиндрических моделей диаметром 20 мм и 30 мм с плоским торцом в носовой части при различных расстояниях между передней критической точкой моделей и срезом сопла, которое варьировалось в диапазоне от 25мм до 50мм. Ключевые слова: диссоциированный воздух, гет
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