Many experimental and numerical investigations of arrays of impingement cooling jets have been performed. A lot of them have addressed the problem of cooling with jets directed perpendicularly or inclined to the planar plate. However, in many technical applications contour of the cooled surface is more complex. One of the examples is a casing of the low-pressure turbine of the jet engine. It’s shape is determined by the turbine flow path and position of the blades and vanes located circumferentially inside the casing. Position of the cooling jets is limited by surrounding components, thermal expansion and vibrations occurring during the engine operation. The investigation focused on the area at which the air has to be blown to achieve most effective cooling system for the complex geometry of the cooled surface is still open. The main goal of the numerical investigation performed in this study was to examine various axial positions of the jets directed perpendicularly to the non-planar shape of the surface to achieve the most effective Nusselt number distribution. Twenty-one analyses with different locations of array of cooling nozzles and various temperature ratios were taken into consideration. The numerical calculations of the thermal and flow parameters were performed using computational fluid dynamics code Ansys CFX.

Modern low-pressure turbine engines are equipped with casings impingement cooling systems. Those systems (called Active Clearance Control) are composed of an array of air nozzles, which are directed to strike turbine casing to absorb generated heat. As a result, the casing starts to shrink, reducing the radial gap between the sealing and rotating tip of the blade. Cooling air is delivered to the nozzles through distribution channels and collector boxes, which are connected to the main air supply duct. The application of low-pressure turbine cooling systems increases its efficiency and reduces engine fuel consumption.