Engineering topics

Anthony E Washburn

Publications and source records attributed to Anthony E Washburn.

4 records

NASA NTRSDate not supplied

A Separation Control CFD Validation Test Case: Baseline and Steady Suction - Part 1

Low speed flow separation over a wall-mounted hump, and its control using steady suction, were studied experimentally in order to generate a data set for a workshop aimed at validating CFD turbulence models. The baseline and controlled data sets comprised static and dynamic surface pressure measurements, flow field measurements using Particle Image Velocimetry (PIV) and wall shear stress obtained via oil-film interferometry. In addition to the specific test cases studied, surface pressures for a wide variety of conditions were reported for different Reynolds numbers and suction rates. Stereoscopic PIV and oil-film flow visualization indicated that the baseline separated flow field was mainly two- dimensional. With the application of control, some three-dimensionality was evident in the spanwise variation of pressure recovery, reattachment location and spanwise pressure fluctuations. Part 2 of this paper, under preparation for the AIAA Meeting in Reno 2005, considers separation control by means of zero-efflux oscillatory blowing.

David Greenblatt↗

NASA NTRSDate not supplied

TPSAS-NF1676L-27686-DND

Accurate flight prediction methods are critical for all aspects of vehicle performance, handling characteristics, and structural integrity. The first NASA/Industry/DoD workshop on wind tunnel/flight correlation was held in 1981, when discrepancies arising from Reynolds number effects, aeroelastic effects, and tunnel wall and sting interference effects posed significant barriers to experimentally-based prediction methods in use at that time. Significant advances in ground-based experimental capabilities and facilities, CFD methods, and flight test technology in the next 20 years significantly improved the tools available for predictions. In addition, numerous new production and experimental military and civil aircraft completed flight testing, offering an unprecedented experience base and data for assessing the accuracy of current prediction methods and practices. Thus, the first Flight Prediction Workshop (FPW) was held in 2002. The objective of the 2002 workshop and the current 3 day workshop for technical specialists is to provide a forum for the exchange of: experiences and lessons learned, critical assessments of the state of the art, and recommendations for further developments in flight prediction methodology. Information and opinions provided by the workshop will be incorporated in R&T planning for future government activities in aerodynamics, aeroelasticity, aeroacoustics, propulsion/air frame integration, etc.

Joseph H Morrison↗

NASA NTRSDate not supplied

High Reynolds Number Testing of the NATO AVT-298 SWiFT Configuration at the National Transonic Facility

A high Reynolds number wind tunnel test of the NATO AVT-298 Swept Wing Flow Test (SWiFT) configuration was conducted in the National Transonic Facility at the NASA Langley Research Center during the summer of 2023. The SWiFT research model geometry has relevance to both blended/hybrid wing body (BWB/HWB) and unmanned combat aerial vehicle (UCAV) configurations, and the test campaign was the culmination of an international collaboration under the NATO AVT-298 research task group. The main objectives of the test were to investigate Reynolds number scaling effects on low-speed stability & control characteristics and to examine the onset and progression of flow separation on the wings particularly near the wing crank. Force & moment and surface pressure data were acquired at Mach numbers from 0.2 to 0.8, Reynolds numbers from 2.5 to 34 million, angles of attack from -3 to 20 degrees, and sideslip angles from -10 to 10 degrees. Boundary layer transition detection techniques utilizing static pressure taps, unsteady pressure transducers, and sublimating chemicals were used on the model in a free/natural transition state or a forced transition state using trip dots. Pressure sensitive paint was used to obtain a global surface pressure profile on the model and an advanced laser velocimetry technique was used to obtain velocity measurements in the wake downstream of the wing crank. The results from the test showed clear Reynolds number scaling effects on the maximum lift coefficient and pitching moment coefficient at Mach 0.2, while also capturing significant hysteresis effects. The data acquired from the test will ultimately help improve computational aerodynamic analysis and design tools for application to future BWB-type vehicle configurations.

NATO AVT-298↗

NASA NTRSDate not supplied

Introduction to the NATO AVT-298 Task Group and Development of the SWiFT Configuration

Reynolds number effects are a key development risk for blended wing body aircraft, particularly at high lift take-off and landing conditions. The full scale aerodynamics of these configurations are thought not to be well represented in industry standard low Reynolds number test facilities and the capability to predict Reynolds number effects using computational fluid dynamics or otherwise is not proven. The NATO AVT-298 research task group was established to investigate these issues and this paper sets out the background, motivations and the collaborative approach as well as the development of a new research configuration to serve as a focus for the research. The ‘SWiFT’ configuration, was developed to exhibit flow physics of interest to the AVT-298 research task group and to be suitable for an experimental campaign. The group collaboratively developed the research configuration to be relevant for related blended-wing-body aircraft programmes using computational fluid dynamics and wing design methods and considering the practicalities of testing. This research targets an improvement in our capability to design, optimise and mature future blended wing body aircraft.

SWiFT↗