Showing papers by "Christopher K. W. Tam published in 1983"
TL;DR: In this article, a linear acoustic solution for a helicopter rotor blade with a blunt leading edge operating at high transonic tip Mach number is studied, and it is shown that these characteristic features are caused by the contributions of higher harmonics which decrease in magnitude only as n 1 2 in the limit n → ∞.
25 citations
01 Apr 1983
TL;DR: In this paper, a linear solution for modeling the shock cell structure of an axisymmetric supersonic jet operated at off-design conditions is developed by the method of multiple scales.
Abstract: A linear solution modeling the shock cell structure of an axisymmetric supersonic jet operated at off-design conditions is developed by the method of multiple-scales. The model solution takes into account the gradual spatial change of the mean flow in the downstream direction. Turbulence in the mixing layer of the jet has the tendency of smoothing out the sharp velocity and density gradients induced by the shocks. To simulate this effect, eddy viscosity terms are incorporated in the model. It is known that the interaction between the quasi-periodic shock cells and the downstream propagating large turbulence structures in the mixing layer of the jet is responsible for the generation of broadband shock associated noise. Experimentally, the dominant part of this noise has been found to originate from the part of the jet near the end of the potential core. Calculated shock cell spacing at the end of the jet core according to the present model is used to estimate the peak frequencies of the shock associated noise for a range of observation angles. Very favorable agreement with experimental measurements is found.
7 citations