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- Experimental investigation of acceleration characteristics of a turbojet engine including regions of surge and stall for control applications
- The acceleration characteristics, in the region of maximum acceleration and compressor stall and surge, of an axial-flow turbojet engine with a fixed-area exhaust nozzle were determined by subjecting the engine to fuel flow steps, ramps, and ramps with a sine wave superimposed. From the data obtained, the effectiveness of an optimalizer type of control for this engine was evaluated. At all speeds above 40 percent of rated, a maximum acceleration was not obtained until the engine reached the point of stall or surge. A sharp drop, as high as 80 percent of maximum, in acceleration then occurred as the compressor entered surge of stall. With the maximum acceleration occurring at the point of surge or stall, the optimalizer-type control could not prevent the engine from entering surge or stall. Effective operation of the control may still be possible by sensing the sharp drop in acceleration experienced at the point of stall or surge and using this signal to limit fuel flow. The success of this type of operation would depend on the magnitude of the stall-recovery hysteresis.
- A Semiempirical Procedure for Estimating Wing Buffet Loads in the Transonic Region
- Report presenting wing buffeting data obtained from a flight loads investigation of two jet-propelled swept-wing airplanes to study the effects of Mach number and reduced frequency on the wing buffet loads. Consistent trends were noted between the flight testing and wind-tunnel testing that the results of this particular test were compared with. Results regarding variation with penetration and dynamic pressure, variation with Mach number and reduced frequency, and estimation of wing buffet loads are provided.
- Component performance investigation of J71 experimental turbine 1: Over-all performance with 97-percent-design stator areas
- From Summary: "The over-all component performance characteristics of a J71 experimental three-stage turbine with 97 percent design stator areas were determined over a range of speed and pressure ratio at inlet-air conditions of approximately 35 inches of mercury absolute and 700 degrees R. The turbine break internal efficiency at design operating conditions was 0.877; the maximum efficiency of 0.886 occurred at a pressure ratio of 4.0 at 120 percent of design equivalent rotor speed. In general, the turbine yielded a wide range of efficient operation, permitting flexibility in the choice of different modes of engine operation."
- Temperature in a J47-25 Turbojet-Engine Combustor and Turbine Sections During Steady-State and Transient Operation in a Sea-Level Test Stand
- From Summary: "In order to determine the conditions of engine operation causing the most severe thermal stresses in the hot parts of a turbojet engine, a J47-25 engine was instrumented with thermocouples and operated to obtain engine material temperatures under steady-state and transient conditions. Temperatures measured during rated take-off conditions of nozzle guide vanes downstream of a single combustor differed on the order of 400 degrees F depending on the relation of the blades position to the highest temperature zone of the burner. Under the same operation conditions, measured midspan temperatures in a nozzle guide vane in the highest temperature zone of a combustor wake ranged from approximately 1670 degrees F at leading and trailing edges to 1340 degrees F at midchord on the convex side of the blade."
- Investigation of turbines suitable for use in a turbojet engine with high compressor pressure ratio and low compressor-tip speed 6: experimental performance of two-stage turbine
- The brake internal efficiency of the highly loaded two-stage turbine was 0.79 equivalent design work and speed. The maximum brake internal efficiency was 0.84. A radial survey revealed these major defects: (1) the first-rotor throat area was too large, and a large area of underturned flow existed near the tip;(2) considerable underturning existed at the second-stator outlet; and (3) tangential components of velocity at the turbine outlet amounted to 2.5 points in turbine efficiency.
- Wind-Tunnel Investigation at Mach Numbers From 0.8 to 1.4 of Static Longitudinal and Lateral-Directional Characteristics of an Unswept-Wing Airplane Model
- "Results are presented for a wind-tunnel investigation of an airplane model with a 3.4-percent-thick unswept wing of aspect ratio 2.45 at Mach numbers from 0.8 to 1.4 at a Reynolds number of 1.5 million. Longitudinal characteristics are presented for the basic model and for configuration variations involving two types of wing camber, an area-rule fuselage modification, various external-store arrangements, several conventional missile installations and one designed according to the moment-of-area concept, and two fuselage dive-flap arrangements. Lateral-directional characteristics of the basic model with and without the empennage are also included" (p. 1).
- Aerodynamic design of axial-flow compressors: Volume 3
- Chapters XI to XIII concern the unsteady compressor operation arising when compressor blade elements stall. The fields of compressor stall and surge are reviewed in Chapters XI and XII, respectively. The part-speed operating problem in high-pressure-ratio multistage axial-flow compressors is analyzed in Chapter XIII. Chapter XIV summarizes design methods and theories that extend beyond the simplified two-dimensional approach used previously in the report. Chapter XV extends this three-dimensional treatment by summarizing the literature on secondary flows and boundary layer effects. Charts for determining the effects of errors in design parameters and experimental measurements on compressor performance are given in Chapters XVI. Chapter XVII reviews existing literature on compressor and turbine matching techniques.