ABSTRACTA single, high-amplitude pressure wave rotating with supersonicvelocity about the combustion chamber axis has been observed duringthe resonant (oscillatory) combustion mode of several liquid rocketresearch engines. The occurrence of this very steep-fronted disturb-ance has led to the investigation of the applicability of a rotatingdetonation-like wave concept to explain the phenomenon. Results of aportion of the experimental phase of the investigation are presentedshowing the chamber boundary pressure distribution associated withresonant combustion exhibited by one of these engines. The enginewas operated with nitric acid and aniline/fuffuryl alcohol propellantsat a nominal thrust of 20,000 lb and 300 psia chamber pressure.The pressure distribution was obtained by several simultaneoushigh-frequency-response measurements across the radius of the in-jector face and along the length of the l l-in.-diameter cylindricalchamber. The pressure-wave-to-chamber-wall intersection was foundto curve in the direction of wave rotation with the nozzle end of theintersection leading the injector end in excess of 40 deg circumfer-entially. The wave-to-injector-face intersection was found to be non-radial and to extend into the central area of the face- though thedefinition of the intersection was poor in this area.The observed pressure ratio across the wave front (ratio of peak-to-minimum pressures during a wave rotation period) varied along thechamber wall from in excess of 20:1 near the injector to 4:1 near thenozzle entrance. The pressure ratio at the face varied from approxi-mately 20:1 in the outer half radius to less than 4:1 near the center.The nonsymmetrical wave exhibited a rise time of less than 3 tzsec atcertain boundary locations.A discussion on the performance of the high-response instrumenta-tion system is also presented. The principal areas of this discussioninclude:1. Results of tests to evaluate the uncooled quartz transducer andthe 80-kcps-response FM analog record/playback equipment.2. Advanced techniques for minimizing the effects on transduceroutput of temperature and vibration along with a discussion ofthe effects of these protective techniques on basic transducerfrequency response.3. Results of shock tube and rocket engine tests as applicable to thetransducer system evaluation.