Accession Number : ADP007526

Title :   Prediction of Jet Mixing Noise for High Subsonic Flight Speeds,

Corporate Author : DEUTSCHE FORSCHUNGSANSTALT FUER LUFT- UND RAUMFAHRT E V BRUNSWICK (GERMANY F R)

Personal Author(s) : Michel, Ulf ; Boettcher, Jan

Report Date : APR 1992

Pagination or Media Count : 9

Abstract : A method for the prediction of single stream jet mixing noise in flight is presented that can be used for flight Mach numbers up to 0.9. The method is similar to the empirical SAE method. However, two important results of the theoretical scaling law of Michalke and Michel are incorporated: (1) the total noise of heated jets is separated into quadrupole and dipole noise components because they are influenced differently by the flight Mach number and, (2) the influence of the stretching of the jet plume in flight on the overall sound pressure and the frequency of the emitted sound is considered. A relative velocity exponent law is used to correlate experimental flyover data. The correlation is based on all available data for combat aircraft with fuselage mounted engines and flight Mach numbers between 0.5 and 0.9. The difference between predictions with this new method and measured overall flyover levels is generally less than two decibels. The spectra are also well predicted.

Descriptors :   *JET AIRCRAFT NOISE, *AIRCRAFT ENGINE NOISE, *SUBSONIC FLIGHT, *FLIGHT SPEEDS, *MILITARY AIRCRAFT, AIRCRAFT, CORRELATION, DIPOLES, ENGINES, FLIGHT, FREQUENCY, FUSELAGES, MACH NUMBER, MIXING, NOISE, NUMBERS, PLUMES, PREDICTIONS, PRESSURE, SOUND, SOUND PRESSURE, SPECTRA, STREAMS, VELOCITY, WARFARE, FIXED WING AIRCRAFT.

Subject Categories : Acoustics
      Military Aircraft Operations

Distribution Statement : APPROVED FOR PUBLIC RELEASE