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Three advanced analyses for predicting aircraft propeller performance at high subsonic speeds are Aescribed. Two of these analyses use a hiring line representation for the propeller blades; and vortex filaments for the blade wakes but differ in the details of the solution. The third analysis is a finite difference solution of the unsteady, three-dimensional Euler equations for the flow between adjacent blades. Analysis results are compared to data for a high speed propeller having 8 swept blades integrally designed with the spinner and nacelle. These analyses provide tools for the propeller designer ranging from a short running program for initial design studies to a very long running program for checking final configurations.

An argon ion laser velocimeter (LV) with four beams has been used to measure the detailed flowfield of an advanced eight blade propeller with 4S· of tip sweep in the Lewis 8x6 Foot Supersonic Wind Tunnel. The propeller was tested at a Mach number of 0.8. The propeller operated at an advance ratio of 3.06 and a blade angle at the three-fourths radius of 60.5·. The test configuration was also analyzed using a curved lifting line analysis. A comparison of analysis results with LV data indicated blade blockage occurred near the nacelle. This resulted in a deceleration ahead of the blade and unsteady flow downstream. The LV data also indicated the presence of a shock wave emanating from the suction surface at a radius ratio of 0.79. The curved lifting line analysis qualitatively predicted the SR-3 propeller flow field. The comparison showed some differences between prediction and LV measurements. These aifferences can be attributed to phenomena not included in tne analysis such as viscous blade wakes, tip vortex rollup, blade blockage, and nacelle effects. Tne comparison has indicated underpredictions in the magnitude of the radial velocity jump across the blade. These differences lead to differences in blade loading and wake location. advance ratio, Vo/nD Mach number rotational speed, revolutions per second power, kW (ft-lb/sec) radius, cm (in.) blade tip radius, cm (in.) free-stream velOCity, m/sec (ft/sec) tip rotational velocity, m/sec (ft/sec) axial distance from nose of spinner, cm (in. ) ratio of total temperature to standard sea-level temperature of 518.7· R free-stream density, kg/m 3 (slugs/ft 3 )

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