Selection of the Required Cooling Air Flow Through the Blades of the Axial Turbine at the Initial Design Stage

At the step of preliminary thermodynamic calculation of a gas turbine engine (GTE), the operating parameters of the main engine components and systems are assigned in order to obtain an initial general estimate of the characteristics of the designed GTE. It is important that these estimates are accurate enough to reduce the discrepancies between the design data and the results obtained from the verification 3D calculations in the further design steps. The system that we focus on in the paper, and whose performance is also evaluated in the preliminary design step, is the turbine cooling system. During the conceptual design step, it is necessary to estimate the required cooling air flow rate to ensure the performance of the designed cooled turbine. This paper presents an approach for estimating the required cooling air flow rate during the turbine preliminary design step. Calculated data on the thermal state of nozzle vanes and rotor blades of high-temperature turbines available at the Department of Theory of Aircraft Engines of Samara University are summarized and compared with statistical data from textbooks and articles. For the nozzle vanes of the first stage of a high-pressure turbine with air flow rate greater than 10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">%</sup> relative to the throat of the nozzle vane, we propose an intrinsic dependence for finding the required air flow rate.