Supersonic Transport Noise Reduction Technology Program -Phase II,Volume 2.

摘要

Both compressor and turbine noise were studied in the turbomachinery noise reduction areas. A 3-stage low pressure compressor with variable-flap inlet guide vanes was tested at General Electric's outdoor test site. A hybrid inlet,which employs airflow accereration supression in combination with wall acoustic treatment,was investigated as the suppression device for all three noise monitoring point operating conditions. The effect of auxiliary inlets on noise leakage and suppression was studied for takeoff mode. Also,variable inlet guide vane flaps were used to reduce area and generate high passage Mach numbers a another means of compressor noise suppression. Turbine noise was studied using a J85engine with massive inlet suppressor and open nozzle to unmask the turbine. Second-stage turbine blade/nozzle spacing and exhaust acoustic treatment were investigated as means of turbine noise suppression. The best performing components from noise suppression work performed under the jet and turbomachinery noise reduction tasks were integrated into a viable-type aircraft-engine system study. Overall system noise was evaluated from EPNL estimates of the suppressed and unsuppressed SST systems relating to the current FAR Part 36Noise Regulations.