RESUMO
An extensive study devoted to modelling blade cooling was undertaken at CEAT a few years ago in collaboration with SNECMA. For the turbomachinery applications, an experimental configuration of a turbulent boundary layer with heat transfer was studied for compressible and incompressible flows. The research presented here is a part of that study and this paper reports on the experimental results of an investigation concerned with a row of transonic jets interacting with a transverse flow. In many applications, the cooling layer does not emerge onto the surface from a tangential slot but comes from a slot normal to or inclined to what is otherwise a flush surface. In this case the freestream interacts with the coolant flow. The secondary (jet) flow is introduced at an angle of 45 degrees to the mainstream flow direction. Visualization studies using the surface flow patterns and surface temperature flow patterns are reported and discussed.
RESUMO
An experimental investigation of film cooling of a wall in a case of double rows of staggered hot jets (65 degrees C) in an ambient air flow. The wall is heated at a temperature value between the one of the jets and the one of the main flow. Experiments have been carried out for different injection rates, the main flow velocity is maintained at 32 m/s. Association of the measures of temperature profiles by cold wire and the measures of wall temperature by infrared thermography allows us to describe the behaviour of the flows and to propose the best injection which assures a good cooling of the plate.
RESUMO
An experimental investigation of heat transfer from a single round free jet, impinging normally on a flat plate is described. Flow at the exit plane of the jet is fully developed and the total temperature of the jet is equal to the ambient temperature. Infrared measurements lead to the characterization of the local and averaged heat transfer coefficients and Nusselt numbers over the impingement plate. The adiabatic wall temperature is introduced as the reference temperature for heat transfer coefficient calculation. Various nozzle diameters from 3 mm to 15 mm are used to make the injection Mach number M vary whereas the Reynolds number Re is kept constant. Thus the Mach number influence on jet impingement heat transfer can be directly evaluated. Experiments have been carried out for 4 nozzle diameters, for 3 different nozzle-to-target distances, with Reynolds number ranging from 7200 to 71,500 and Mach number from 0.02 to 0.69. A correlation is obtained from the data for the average Nusselt number.
