Acoustical Characteristics of the Airesearch Model Gtp331-30 Gas Turbine Engine and Development of High-Temperature Vibration-Damping Coatings for Noise Control

摘要

Acoustical power level spectra and directivity indices in one-third octave bands were measured by the free-field method, with use of both a straight exhaust duct and a right-angle duct. One-third octave acoustic power level spectra were obtained for the cooling fan, accessory case, compressor inlet, and turbine plenum by use of the reverberant-room method. Tape recordings of each noise source were subjected to narrow-band analyses and local peaks correlated with engine processes. Three types of coatings were tested: vitreous enamels; high-manganese alloys; and aluminum-alumina cermets.