An analytical and experimental comparison of the flow field of an advanced swept turboprop

Abstract

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 )

Numerical Simulation of a Counter-Rotative Open Rotor Using Phase-Lagged Conditions: Initial Validation on a Single Rotor Case

“…The boundary layer represents around 90% of the losses generated along the extent of the blade between x/D = -0.17 and -0.11. This contribution is the main source of losses in the configuration and is in agreement with previous studies [40,41].…”

Prediction of high speed propeller flow fields using a three-dimensional Euler analysis

“…The uprunning characteristic form of the compatibility equation, with the appropriate A and ~i's is written as r" r peE; z (16) For the grid being used" for this problem, E;r = E;d = ° at the down-stream boundary, causing a simplification of Eq. (16)."…”

“…If this was not the case, Eq. (16) would have to be solved simultaneously with the v~and w-momentum equation.…”