Survey Of Primary Flow Measurement Parameters At The Nasa Langley Transonic Dynamics Tunnel

Survey of Primary Flow Measurement Parameters at the NASA Langley Transonic Dynamics Tunnel

Survey of Primary Flow Measurement Parameters at the NASA Langley Transonic Dynamics Tunnel

An assessment of the methods and locations used to measure the primary flow conditions in the NASA Langley Transonic Dynamics Tunnel was conducted during calibration activities following the facility conversion from a Freon-12 heavy-gas test medium to R-134a. A survey of stagnation pressure, plenum static pressure, and stagnation temperature was undertaken at many pertinent locations in the settling chamber, plenum, and contraction section of the wind tunnel and these measurements were compared to those of the existing primary flow measurement systems. Local flow velocities were measured in the settling chamber using a pitot probe. Results illustrate that small discrepancies exist between measured primary tunnel flow conditions and the survey measurements. These discrepancies in tunnel stagnation pressure, plenum pressure, and stagnation temperature were found to be approximately +/- 1-3 psf and 2-3 degrees Fahrenheit. The propagation of known instrument errors in measured primary flow conditions and its impact on tunnel Mach number, dynamic pressure, flow velocity, and Reynolds number have been investigated analytically and shown to require careful attention when considering the uncertainty in measured test section conditions.Piatak, David J.Langley Research CenterTRANSONIC WIND TUNNELS; FLOW MEASUREMENT; STAGNATION PRESSURE; STATIC PRESSURE; STAGNATION TEMPERATURE; CALIBRATING; FLOW VELOCITY; REYNOLDS NUMBER; DYNAMIC PRESSURE

NASA Technical Memorandum