The frequency of the instability was 525 Hz, with an amplitude of approximately 1.5-psi peak-to-peak at a burner pressure of 200 psia. Prior to designing the experimental rig, a survey of aircraft engine combustion instability experience identified an instability observed in a prototype engine as a suitable candidate for replication. The rig has many of the complexities of a real engine combustor, including an actual fuel nozzle and swirler, dilution cooling, and an effusion-cooled liner. Under this program, a single-nozzle, liquid-fueled research combustor rig was designed, fabricated, and tested. The NASA Glenn Research Center at Lewis Field is leading the Combustion Instability Control program to investigate methods for actively suppressing combustion instabilities.
Future plans are to develop and demonstrate combustion instability control using this experimental combustor rig. Experimental testing in the spring of 1999 demonstrated that the rig can be tuned to closely represent an instability observed in engine tests. The experimental rig has features similar to a real engine combustor and exhibits instabilities representative of those in aircraft gas turbine engines. Because active control of these instabilities may allow future combustors to meet both stringent emissions and performance requirements, an experimental combustor rig was developed for investigating methods of actively suppressing combustion instabilities. Low-emission combustor designs are prone to combustor instabilities. This paper contains the methodology and test results used to verify the quality of the SHJAR rig.Įngine-Scale Combustor Rig Designed, Fabricated, and Tested for Combustion Instability Control Research
#CONTROLLING WAVES MULTIRACK WITH CL5 FULL#
Finally, a full set of baseline data was acquired. Other tests performed characterized the amplitude and frequency of the valve noise, confirmed the location of the acoustic far field, and documented the background noise levels under several conditions. Experiments using boundary layer treatment and hot wire probes documented this noise source and its removal, allowing clean testing of low Reynolds number jets. This method led to the identification of a high frequency noise source related to the Reynolds number. Effectively, any noise source that did not follow these rules of jet noise was labeled as rig noise.
Jet noise and rig noise were separated by using the distance and velocity scaling properties of jet noise. Towards this goal, a methodology was employed dividing all noise sources into three categories: background noise, jet noise, and rig noise.
#CONTROLLING WAVES MULTIRACK WITH CL5 SERIES#
The first series of tests on the SHJAR were designed to prove its capabilities and establish the quality of the jet noise data produced. The Small Hot Jet Acoustic Rig (SHJAR), located in the Aeroacoustic Propulsion Laboratory (AAPL) at the NASA Glenn Research Center in Cleveland, Ohio, was commissioned in 2001 to test jet noise reduction concepts at low technology readiness levels (TRL 1-3) and develop advanced measurement techniques. Information presented in this report summarizes free-jet performance, fluid support systems, and data acquisition capabilities of the NATR. The dome serves to protect the surrounding community from high noise levels generated by the nozzles, and to provide an anechoic environment for acoustic measurements.
Acoustic and aerodynamic data are collected from test nozzles mounted in the free-jet flow. This ejector is operated with 125 lb/s of compressed air, at 125 psig, to achieve 375 lb/s at Mach 0.3. diameter and is driven by an air ejector. Located inside an acoustically treated dome with a 62-ft radius, the NATR is a free-jet that has a 53-in. Trade-off studies are conducted to compare performance and noise during simulated low-speed flight and takeoff. The facility is capable of measuring the acoustic and aerodynamic performance of aircraft engine nozzle concepts. The nozzle acoustic test rig (NATR) was built at NASA Lewis Research Center to support the High Speed Research Program. The Nozzle Acoustic Test Rig: an Acoustic and Aerodynamic Free-jet Facility
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