Prediction of Noise Emission from the NASA SR-2 Propeller

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This study looked into the DES simulations of the eight bladed NASA SR-2 propeller. The 24.5 inch diameter propeller was simulated at Mach 0.6, with and without the presence of a straight aft wing of NACA0010 profile, to investigate the effects on the level of aero-acoustic noise detected on 12 microphone probes.

The geometry of the straight-blade SR-2 propeller, along with the area-ruled spinner and contoured nacelle, were generated within the simulations based on available literature. The acoustic plate, housing all the microphones, was included in the simulations so as to provide a better representation of the wind tunnel setup. Inferences from literature led to the simulation setup utilizing a static pressure of 90110Pa and a temperature of 279°K. The propeller was prescribed a rotation rate of 6330.5RPM in order to generate a propeller helical Mach of 0.86 and a propeller advance ratio of 3.06, matching the data from the well-documented wind tunnel test of the SR-2 propeller (NASA-TM-101480). A -0.4° adjustment in the propeller blade angle was required to match the experimental power coefficient of 1.32. Direct measurements of the noise at probe 4 to 11 matched well with the experimental data, with probe 6 (slightly aft of propeller plane) registering a difference of 1.173dB.

The addition of the straight aft wing within the simulation suggested a reduction in noise for most of the probe points, with probe 6 registering a drop of 0.66dB. However, without relevant experimental data on such a setup, the results of the simulated SR-2 with aft wing remains inconclusive. Literature review on the aeroacoustics impact of tractor configuration returned ambiguous findings as their test conditions varied.

Author Company: 
DSO National Laboratories
Author Name: 
Keng Soon Voo