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UNSTEADY AERODYNAMICS, AEROACOUSTICS AND AEROELASTICITY OF TURBOMACHINES Episode 5

Tham khảo tài liệu 'unsteady aerodynamics, aeroacoustics and aeroelasticity of turbomachines episode 5', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 200 Figure 4. Pitch - wise distributions of the 1-st harmonic of vorticity near vortical wake axis A 10mm Figure 5. Distribution of the 1-st harmonic of free vortexes intensity along parallel front line Structure of Unsteady Vortical Wakes behind Blades of an Axial Turbomachine 201 Figure 6. Teoretical distribution across vortical wake of the 1-st harmonic of free vortrxes intensity Figure 7. Distribution of amplitude of the 1-st harmonic of free vortexses intensity along parallel front line THE EFFECT OF MACH NUMBER ON LP TURBINE WAKE-BLADE INTERACTION M. Vera H. P. Hodson Whittle Laboratory University of Cambridge UK R. Vazquez ĨTP. Industria de Turbo Propul sores Madrid SPAIN Abstract The techniques employed in high speed linear cascade testing to simulate the effect of unsteadiness are presented and compared with low speed counterparts. Results are obtained from a high speed cascade and a low speed cascade. Both are models of an existing conventional low pressure turbine blade. They are compared under steady and unsteady lbw conditions. The results show that the same quantitative values of losses are obtained proving the validity of the low speed approach for profiles with an exit Mach number of the order of 0.64. The range of validity of the conclusions is extended by reference to a profile designed using current low pressure turbine design practice. Wake traverses using pneumatic probes reveal that the unsteadiness reduced the profile losses up to Mach numbers of 0.9 1. Introduction The development of the low pressure turbine LPT has reached a stage where rises in efficiency are difficult to obtain. Furthermore the LPT could represent one third of the total engine weight. Therefore one of the current trends that designers have adopted is to improve the overall performance of the LPT by reducing its weight. This new philosophy leads to fewer blades each of which carries a greater aerodynamic load. The LPT operates at the lowest Reynolds number in the whole .