Laser-velocimeter flow-field measurements of an advanced turboprop

Abstract

SummaryNon-intrusive measurements of velocit y about a spinner-propellernacelle configuration at a Mach number of 0.8 have been performed. A laser velocimeter., s p ecifically develcoed for these measurements in the NASA Lewis 8-by 6-foot Supersonic Wind Tunnel, was used to measure the flow-field of the advanced swept SR-3 prooeller. The laser velocimetPr uses an ar g on ion laser and a 2-color optics system to allow simultaneous measurements of ')-comoonents of velocity. The axisvmmetric nature of the propeller-nacelle flow-field permits two separate 2-dimensional measurements to be combined into 3-dimensional velocity data. Presented are data ahead of and behind the propeller bladef-and also a limited set in between the blades. As p ects of the observed flow-field such as the tip vortex are discussed.

Interaction between rotors of a counter rotating propeller

“…Forward and aft rotor RPMs at the nominal setting were held constant at 15,300 and 14,600, respectively. 4 To establish the interaction mechanism in the flow one must document the influence of the two rotors on each other so that thc true mean wave form of the flow time history can be establishcd. A method of conditional sampling has been worked out which effectively fixes the rotor positions in time and/or space and permits averaging of the mean wake at any instantaneous location of both the forward and rear rotor blades.…”

“…In this manner the location of each blade can be independently determined for both rotors for each data point because the location of the blades relative to the LED sensor is known. 4 Flow measurements around the CRPs have been obtained by employing a hot-film thermal anemometer located with a travcrsing device between the two rotors as shown in Fig. I .…”