"IGF::OT::IGF" OTHER FUNCTIONS: 1. TASK ORDER TITLE: MAIN ENGINE IGNITION ACOUSTICS FROM HIGH AREA RATIO RO…

Public award description

"IGF::OT::IGF" OTHER FUNCTIONS: 1. TASK ORDER TITLE: MAIN ENGINE IGNITION ACOUSTICS FROM HIGH AREA RATIO ROCKET NOZZLES 2. PURPOSE, OBJECTIVE, AND BACKGROUND OF WORK TO BE PERFORMED: THE DESIGN OF THE SPACE LAUNCH SYSTEMS (SLS) HAS A DIFFERENT ENGINE ARRANGEMENT (BOTH SOLID AND LIQUID) THAN THE SPACE SHUTTLE HAD. IN PARTICULAR, THE THREE RD-25D SPACE SHUTTLE MAIN ENGINES (SSME) THAT WERE CLUSTERED ON THE BACK OF THE ORBITER WERE POINTED AWAY FROM AND WERE AT A HIGHER ELEVATION THAN THE SOLID ROCKET BOOSTERS (SRB). THE SLS, HOWEVER, EMPLOYS FOUR RD-25DS THAT ARE LOCATED CLOSER TO AND AT THE SAME ELEVATION AS THE SRBS. IT IS EXPECTED WITH THIS DESIGN THAT ACOUSTIC LOADS FROM THE SRB AND THE RD-25D WILL BE HIGHER ON THE SLS COMPONENTS THAN THEY WERE FOR THE SHUTTLE. AS A CONSEQUENCE OF THE EXPECTED INCREASE IN NOISE LEVELS FOR THE NEW ROCKET DESIGN, A TEST CAMPAIGN (SMAT) IS PLANNED TO DETERMINE THE VIBROACOUSTIC LOADS PRODUCED BY THE SRB START TRANSIENT ON THE SLS VEHICLE. THE SMAT TEST, HOWEVER, DOES NOT ADDRESS THE RD-25D GENERATED MAIN ENGINE IGNITION (MEI) ACOUSTICS . THE PROPOSED RESEARCH IS DESIGNED TO COMPLEMENT THE SMAT CAMPAIGN BY CONDUCTING A SERIES OF COLD FLOW TESTS IN THE FULLY ANECHOIC CHAMBER TO DETERMINE THE VIBROACOUSTIC LOADS ON THE SLS VEHICLE FROM THE RD-25D MEI ACOUSTICS. THE FOCAL POINT OF THE PROPOSED RESEARCH IS ON DEVELOPING RELIABLE PREDICTIONS OF THE VIBROACOUSTIC LOADS THAT NASA SHOULD ANTICIPATE WITH THE SLS DURING BOTH FULL-SCALE TESTING AND FLIGHT. THE RESEARCH WILL BEGIN BY LEVERAGING FULL-SCALE FLIGHT TEST DATA ACQUIRED DURING THE SPACE SHUTTLE PROGRAM TO DETERMINE THE SCALING BETWEEN COLD-FLOW AND MODEL-SCALE TESTS. THIS WILL ENCOMPASS THE EFFECTS PRODUCED BY THE STAGGERED START OF THE SSME (CLUSTER OF THREE RD-25D ENGINES). THE CLUSTER OF THREE NOZZLES WILL BE TESTED IN A HORIZONTAL CONFIGURATION AND IN THE ABSENCE OF GROUND REFLECTION TO GAUGE AN UNDERSTANDING THE MEI ACOUSTICS ENVIRONMENT. THE SECOND PHASE OF THE PROGRAM WILL FOCUS ON A CLUSTER OF FOUR ENGINES TO SIMULATE THE SLS LAUNCH ENVIRONMENT. TESTS WILL BE CONDUCTED WITH AND WITHOUT THE PRESENCE OF A BOOSTER BODY AND WITH AND WITHOUT VARIOUS ENGINE START STAGGERS. INITIAL MEASUREMENTS WILL INVOLVE HORIZONTAL ENGINE STARTS, FOLLOWED BY A VERTICAL CONFIGURATION SIMULATING A SLS CORE STAGE GREEN RUN TEST. SPECIFIC DETAILS CONCERNING THE PHASES OF THE PROPOSED RESEARCH ARE OUTLINED AS FOLLOWS. POP - 07/02/2013 - 9/30/14