An investigation was conducted in the NACA Lewis altitude wind tunnel to determine the effect of nonuniform inlet-air velo¬cities on the performance of a full-scale axial-flow turbojet engine. Total-pressure variations as large as 103 pounds per square foot in the radial direction and 90 pounds per square foot in the circumferential direction at 30,000-foot altitude were obtained by the use of obstructions in the engine-inlet ducting. Data were obtained at altitudes from 20,000 to 50,000 feet at a flight Mach number of approximately 0.21 and corrected engine speeds from 77.3 percent of rated speed to rated engine speed.n. For some of the configurations and operating conditions inves¬tigated, the effect of distortions of the inlet-velocity pattern on the internal aerodynamics of the engine resulted in slight improve¬ments in performance;at other operating conditions the performance was slightly impaired. These effects are distinct from the perform¬ance losses associated with losses in ram-pressure recovery. With the inlet-velocity distortions investigated, the net thrust varied between 0.95 and 1.03 of the net thrust with the uniform inlet con¬figuration at the same operating conditions. Similarly, the ratio of specific-fuel-consumption values varied from 1.00 to 1.04. In general, compressor efficiencies were slightly reduced by the non¬uniform inlet-velocity distributions. It may therefore be concluded that performance changes due to the effects of nonuniform inlet vel¬ocity on the internal aerodynamics of the engine investigated do not appear to be serious for the range of distortions investigated.nThroughout the investigation, engine-vibration measurements were carefully observed. Vibration readings were always well below the limits specified by the manufacturer.
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