Experimental investigation of jet noise from a high BPR dual-stream jet in a static model-scale test

Abstract

The noise characteristics of a dual-stream jet of bypass ratios greater than 10 were investigated in response to area ratio, nozzle-operating conditions, installation effect, and chevron effect. The key conclusions were as follows. (1) The area ratio impacted the noise by up to 3 dB at aft angles and at mid-frequency for heated conditions. (2) The spectral variation due to the change of primary stream parameters was constant at low Strouhal numbers and diminished at high Strouhal numbers. (3) The impact of the secondary stream pressure was described by the scaling law of single-stream jets for unheated conditions. The flow parameters of other jets were required to describe the spectra of Strouhal numbers between 0.2 and 2.0, based on the secondary jet for heated conditions. (4) The installed jet noise was quantified for various wing configurations and was more pronounced at forward angles. (5) The chevron nozzle reduced overall noise by up to 4 dB, though it became less attractive when installed. The quantified information is expected to improve the estimation of noise from a dual-stream jet of high bypass ratios.