Improving Optical Access for the Mach-6 Quiet-Flow Ludwieg Tube
Abstract
Hypersonic boundary-layer transition is critical to the development of cruise or glide vehicles such as the X-51, FALCON HTV-2, HAWC, TBG and AHW, as well as reentry vehicles such as the Orion and HIFiRE-5. Although much progress has been made in understanding the basic mechanisms of transition in simple geometries, vehicle designers must often resort to simple algebraic correlations for predictions. The uncertainties in these correlations are often far too great, and thus either flight or ground test data must be obtained. Flight tests are very expensive, and ground tests are corrupted by the high levels of test-section noise in conventional hypersonic tunnels. Quiet-flow wind tunnels are intended to replicate the low noise conditions of actual flight. Achievement of quiet flow requires maintaining a laminar boundary layer on the nozzle wall to avoid acoustic fluctuations generated by boundary layer turbulence. The Boeing/AFOSR Mach 6 Quiet Tunnel at Purdue University was designed and constructed in 1996-2001 to provide affordable quiet flow at moderate Reynolds numbers. Since late 2006, the Purdue Quiet Tunnel has provided fairly reliable quiet flow to about 3:5- 3:8x10^6/ft. The tunnel is heavily used for a variety of projects, many of whom require optical access for imaging heat transfer using temperature-sensitive paint or an infrared camera. Optical access is available through a conformal 7x14-inch rectangular plexiglas window and also a metal 7x14-inch insert with a pair of 5-inch circular windows. However, recent experiments have sought more optical access for simultaneous measurements using several cameras, and these experimental measurements would require additional windows. One additional window of each type is therefore proposed here.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Apr 09, 2018
- Source ID
- FA95501710416
Entities
People
- Steven Schneider
Organizations
- Air Force Office of Scientific Research
- United States Air Force
- University of Virginia