Temperature Effects on Acoustic Interactions between Altitude Test Facilities and Jet Engine Plumes

• Main Authors: Ahuja, K K, Massey, K C, Tan, C K, Jones, III, R R
• Format: Report
• Language: English
• Subjects: ACOUSTIC INTERACTIONS; ACOUSTIC PROPERTIES; Acoustics; ALTITUDE; AMPLITUDE; Astronautics; AXISYMMETRIC; BEHAVIOR; CELLS; COUPLINGS; CYCLES; DIFFUSERS; DUCTS; EJECTORS; ENERGY; FEEDBACK; FLOW; FREQUENCY; HEATING; HIGH TEMPERATURE; INSTABILITY; INTERACTIONS; JET ENGINE PLUMES; JET ENGINES; MACH NUMBER; MICROPHONES; NOISE; NOZZLES; PLUMES; PUMPS; RATIOS; RESERVOIRS; RESONANCE; SIGNATURES; TEMPERATURE; TEST AND EVALUATION; TEST EQUIPMENT; TEST FACILITIES

The overall objective of the present investigation was to determine the mechanisms responsible for engine/test cell resonance observed at the AEDC facility. The specific objective was to determine the effect of heating the jet on its coupling with the diffuser used in a typical engine/test cell facility. This objective was to be accomplished through systematic measurements of cold and heated free and ducted jets using a subscale facility. An additional objective was to analytically examine the behavior of jet instability waves as a function of temperature, and to identify any potential of strong coupling between the jet instabilities and diffuser duct resonance modes directly attributable to heating of the jet. Model cold and heated jet experiments are performed with an axisymmetric convergent nozzle in a test setup that simulates a supersonic jet exhausting into a cylindrical diffuser. The measured data consist of a free and ducted plume for a range of jet exit Mach numbers and four reservoir temperatures: ambient, 400 deg F, 750 deg F, and 1,000 deg F. Analytical results on the growth of instability waves and the duct resonance have been introduced. It is shown that the screech frequency increases with increasing operating temperature ratio. The measured in-duct microphone signatures contain a number of discrete tones, and almost all of them can be associated with duct resonances. The amplitudes increase with increasing Mach number and operating temperature ratios. At certain operating conditions, the acoustic fluctuations associated with these ejector duct modes excite the most amplified wave of the jet. Screech, Altitude test facilities, Instability waves, flow/acoustic interactions, jet noise, Ejectors, Receptivity, Duct resonance, Ducted jets, High temperature jets. Sponsored in part by Arnold Engineering Development Center, Arnold AFB, TN. Prepared in cooperation with Florida State Univ., Tallahasse, FL and Sverdrup Technology Inc./AEDC Group.