LDV measurements of B-747 wake vortex characteristics

PDFTech ReportLMSC-HREC TR D496975DOT-TSC-1145FA-605/705WakesVorticesLaser doppler velocimetersMeasurement of specific phenomenaInstrumentationCaliforniaUnited States. Federal Aviation AdministrationBrashears, M. R.Zalay, A. D.Lockheed Missiles & Space Company, Inc.United States. Dept. of Transportation. Transportation Systems CenterUnited States. Federal Aviation AdministrationNTL-AVIATION-AVIATIONNTL-AVIATION-Aviation Safety/AirworthinessNTL-AVIATION-Air Traffic ControlVolpe National Transportation Systems Center, Technical Reference CenterIn order to determine the behavior of the wake vortices of a B-747 at lowaltitudes and to measure the vortex decay process behind the B-747 as a functionof altitude above ground, flap and spoiler settings and different flight configurations; a B-747 aircraft flew 54 passes at low level over a ground-based laserDoppler velocimeter (LDV) system and other sensors. From the LDV measurements, the location and velocity distribution of the wake vortices and the generalvortex roll-up, transport and decay trends were obtained. Results of the studyindicated that the deployment of spoilers and flaps enhanced the decay of the vortexpeak tangential velocity in the near wake while aircraft altitude glide slope, andlanding gear deployment has little effect. The report discusses the LDV wakevortex measurements including the instrumentation used, the experimental testsequence, and the results of the wake measurements in terms of the vortex roll-up,transport and decay trends, and a comparison of the wake vortex characteristicsfor different configurations