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Some Effects of Rapid Inlet Pressure Oscillation on the Operation of a Turbojet Engine

Description: A program was conducted in an altitude facility at the NACA Lewis laboratory to investigate the effects of rapid inlet pressure oscillations on the operation of a current turbo jet engine. These pressure oscillations were approximately sinusoidal in form and were generated to cover a frequency range of 2 to 75 cycles per second and an amplitude range of 10 to 70 percent of the free-stream total pressure. As the oscillation progressed through the compressor, the amplitude was attenuated considerably and a relatively large phase shift (lag) occurred. Engine stall limits obtained during pressure oscillations differed from quasi-steady-state stall limits as defined by over-all compressor pressure ratio.
Date: January 7, 1958
Creator: Russey, Robert E. & Lubick, Robert J.
Partner: UNT Libraries Government Documents Department

Preliminary Transient Performance Data on the J73 Turbojet Engine. II - Altitude, 35,000 Feet

Description: A program was undertaken to determine the J73 turbojet engine compressor stall and surge characteristics and combustor blow-out limits encountered during transient engine operation. Data were obtained in the form of oscillograph traces showing the time history of several engine performance parameters with changes in engine fuel flow. The data presented in this report are for step changes in fuel flow at an altitude of 35,000 feet, at flight Mach numbers of 0.3, 0.8, and 1.2, and at several engine-inlet temperatures,.
Date: June 29, 1953
Creator: Lubick, Robert J. & Sobolewski, Adam E.
Partner: UNT Libraries Government Documents Department

Altitude operational characteristics of prototype J40-WE-8 turbojet engine

Description: From Introduction: "The altitude performance characteristics of the prototype J40-WE-8 turbojet engine were determined in the NACA Lewis altitude wind tunnel. The altitude operational characteristics of the engine are presented herein. The results of a brief study of the effect of the two different grades of fuel (MIL-F-5624A grades JP-3 and JP-4) on steady-state engine performance at an altitude of 45,000 feet and a flight Mach number of 0.20 are also given."
Date: August 14, 1953
Creator: Sobolewski, Adam E & Lubick, Robert J
Partner: UNT Libraries Government Documents Department

Surge-inception study in a two-spool turbojet engine

Description: Report discussing a study of compressor behavior leading to surge involving extensive instrumentation to obtain information about pressure at various points in the compressor. Information about where and under what conditions rotating stall occurred is given special attention.
Date: 1956
Creator: Wallner, Lewis E.; Lubick, Robert J. & Saari, Martin J.
Partner: UNT Libraries Government Documents Department

Surge-Inception Study in a Two-Spool Turbojet Engine, Revised

Description: A two-spool turbojet engine was operated in the Lewis altitude wind tunnel to study the inception of compressor surge. In addition to the usual steady-state pressure and temperature measurements, the compressors were extensively instrumented with fast-response interstage pressure transducers. Thus it was possible to obtain maps for both compressors, pressure oscillations during rotating stall, effects of stall on efficiency, and stage-loading curves. In addition, with the transient measurements, it was possible to record interstage pressures and then compute stage performance during accelerations to the stall limit. Rotating stall was found to exist at low speeds in the outer spool. Although the stall arose from poor flow conditions at the inlet-stage blade tips, the low-energy air moved through the machine from the tip at the inlet to the outer spool to the hub at the inlet to the inner spool. This tip stall ultimately resulted in compressor surge in the mid-speed region, and necessitated inter-compressor air bleed. Interstage pressure measurements during acceleration to the compressor stall limit indicated that rotating stall was not a necessary condition for compressor surge and that, at the critical stall point, the circumferential interstage pressure distribution was uniform. The exit-stage group of the inner spool was first t o stall; then, the stages upstream stalled in succession until the inlet stage of the outer spool was stalled. With a sufficiently high fuel rate, the process repeated with a cycle time of about 0.1 second. It was possible to construct reproducible stage stall lines as a function of compressor speed from the stage stall points of several such compressor surges. This transient stall line was checked by computing the stall line from a steady-state stage-loading curve. Good agreement between the stage stall lines was obtained by these two methods.
Date: November 7, 1957
Creator: Wallner, Lewis E.; Lubick, Robert J. & Saari, Martin J.
Partner: UNT Libraries Government Documents Department

Preliminary Data on the Effects of Inlet Pressure Distortions on the J57-P-1 Turbojet Engine

Description: An investigation to determine the steady-state and surge characteristics of the J57-P-1 two-spool turbojet engine with various inlet air-flow distortions was conducted in the altitude wind tunnel at the NACA Lewis laboratory. Along with a uniform inlet total-pressure distribution, one circumferential and three radial pressure distortions were investigated. Data were obtained over a complete range of compressor speeds both with and without intercompressor air bleed at a flight Mach number of 0.8 and at altitudes of 35,000 and 50,000 feet. Total-pressure distortions of the magnitudes investigated had very little effect on the steady-state operating line for either the outer or inner compressor. The small radial distortions investigated also had engine over that obtained with the uniform inlet pressure distribution. The circumferential distortion, however, raised the minimum speed at which the engine could operate without encountering surge when the intercompressor bleeds were closed. This increase in minimum speed resulted in a substantial reduction in the operable speed range accompanied by a reduction in the altitude operating limit.
Date: December 3, 1954
Creator: Wallner, Lewis E.; Lubick, Robert J. & Einstein, Thomas H.
Partner: UNT Libraries Government Documents Department

Stall and flame-out resulting from firing of armament

Description: Report presenting an analysis of the causes of compressor stall and flame-out when armament is fired during flight at high altitudes. Experimental data are also presented. The increase in compressor-inlet temperature during armament firing was found to be the most important single factor affecting engine performance.
Date: August 5, 1955
Creator: Childs, J. Howard; Kochendorfer, Fred D.; Lubick, Robert J. & Friedman, Robert
Partner: UNT Libraries Government Documents Department