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A closed mathematical model of heat and mass transfer under the non-isothermal filtration through the organized pores of coolants with a strong dependence of dynamic viscosity on temperature with further injection into a viscous gas-dynamic flotation with the formation of liquid film and evaporation under the influence of aerodynamic heat flows has been developed. The aim of the paper is to develop the physical and mathematical basis of thermal protection with the automatic supply of coolant having a strong dependence of dynamic viscosity on temperature (by 3-5 orders of magnitude when the temperature changes by 200-2500°C). Such thermal protection system allows for operating without the mass removal that preserves the geometry of the structural elements at the intensive heating, which is very relevant. To achieve this goal, a mathematical model of the automatic coolant supply with filtration through the organized pores, injection into a high-temperature gas-dynamic boundary layer with the formation of the protective liquid film and evaporation is formulated. The results with respect to the mass flow rate of the coolant, the mass evaporation rate of the formed liquid film and the temperatures of the structure which in all cases remain below the evaporation temperature of the cooler have been obtained. [ABSTRACT FROM AUTHOR]

A indústria aeronáutica tem grande interesse no estudo dos fluxos aerodinâmicos laminares, uma vez que produzem força de arrasto reduzida, resultando em economia de combustível nas aeronaves. Esse tipo escoamento em torno de superfícies aerodinâmicas e sua transição a turbulento torna-se, portanto, importante para o projeto aeronáutico e validação de modelos de Dinâmica dos Fluidos Computacional (CFD). No entanto, tal determinação apresenta dificuldades experimentais, muitas vezes relacionadas com métodos invasivos, que podem influenciar a camada limite do escoamento na superfície, tornando os dados não-representativos. Este artigo apresenta uma metodologia para determinar a transição da camada limite de laminar a turbulento usando câmeras de imageamento infravermelho de alta sensibilidade. Este método baseia-se no fato de que uma diferença de temperatura na superfície do perfil aerodinâmico sob escoamento laminar e turbulento é induzida por uma diferença na troca de calor entre os dois regimes: a troca de calor é maior em escoamentos turbulentos e pode ser detectada por estas câmeras. A principal vantagem deste método está no fato de que é não-invasivo e, portanto, fornece dados experimentais mais consistentes a fim de validar modelos teóricos com melhor precisão. O trabalho baseia-se em uma apresentação teórica dos conceitos aplicados e ensaios em túnel de vento conduzidos no Laboratório de Aerodinâmica da Escola de Engenharia de São Carlos - USP, por membros desta instituição, em conjunto com pesquisadores da Bombardier Aviation e Universidade Federal de São Carlos - UFSCar.

The article is devoted to the study of the decision support system when analyzing the outflow of a gas jet into a supersonic transverse shear flow based on the results of processing photographs (video frames) in terms of the image intensity parameter. Studies of image intensity matrices using contour analysis and receptor models make it possible to determine with great certainty the position of any section (or a conglomerate of sections) of the gas stream with an estimate of its geometry and area with a given range of image intensities. All this makes it possible to determine regions with a given law of variation in the density of the gas flow from a given interval of image intensity, to reveal the contours of the boundaries of a given flow. The study of the law of change in the intensity of the image in given sections makes it possible to reveal the laws of the flow within them. The application of the Freeman chain code, correlation and regression analyzes allows determining with great certainty the geometric parameters of shock waves, in particular, the slope of the curve at any point of the curve. Taking into account multifactor analysis, if sufficient statistical data are available, the correlation relationship between the density, the pressure in the gas stream and the intensity of the image in the photographs is determined. [ABSTRACT FROM AUTHOR]