Experimental Space Shuttle Orbiter Studies to Acquire Data for Code and Flight Heating Model Validation

As part of an experimental study to obtain detailed heating data over the Space Shuttle Orbiter, CUBRC has completed an 150-run matrix of experiments employing four unique models and two separate hypervelocity wind tunnel facilities. The primary objective of this testing centered around obtaining heating data over heavily instrumented Orbiter wing leading edge sections in the primary shock interaction region where the Orbiter bow shock contacts the wing leading edge. To achieve the goals of this objective data was obtained over a range of Mach numbers from 10 to 18, flight scaled Reynolds numbers, and model attitudes representing points on the Orbiter reentry trajectory. This was done in three phases consisting of a risk mitigation phase using a 1.8% scale aluminum model with special temperature sensitive paint covering the wing leading edge, a 0.9% scale model with high resolution thin-film instrumentation in the span direction, and a primary 1.8% scale model with detailed thin-film resolution in both the span and chord direction in the area of peak heating. This test program was conceived in direct response to the investigation of the accident that occurred during the reentry of the Space Shuttle Columbia (STS-107) in February of 2003. This accident was caused by debris which originated from the foam covering the ET bipod fitting ramps striking and damaging critical wing leading edge heating tiles in the shock interaction region during ascent. Through the extensive investigation of the accident, analysts found that only a limited amount of experimental wing leading edge data existed in this critical peak heating area and a need arose to acquire a detailed dataset of heating in this region. Secondary objectives included obtaining natural or tripped turbulent wing leading edge heating levels, assessing the effectiveness of protuberances and cavities placed at specified locations on the Orbiter over a range of Mach numbers and Reynolds numbers to evaluate and compare against existing experimental and computational data sets; obtaining cavity floor heating to aid in the verification of cavity heating correlations; obtaining control surface deflection heating data on both the main body flap and elevons; and obtaining high speed schlieren videos of the interaction of the Orbiter nose bow shock with the wing leading edge. To support these secondary objectives the primary 1.8% scale Orbiter model was additionally instrumented down the centerline, over the wing acreage on the port side, and painted with temperature sensitive paint on the starboard side wing acreage. In all, the primary 1.8% scale model was instrumented with over three-hundred and twenty highly sensitive thin-film heating sensors, two-hundred of which were located in the wing leading edge shock interaction region. All data obtained in this experimental program will be used for code validation, the upgrading of existing Orbiter heating engineering tools, and to comparison to existing flight and wind tunnel Orbiter heating databases. In addition to the experimental data, CUBRC also performed a large amount of CFD analysis to confirm and validate not only the tunnel flow conditions, but also 3D flows over the Orbiter acreage, wing leading edge, and control surfaces to assess data quality, shock interaction locations, and control surface separation regions. This analysis is a standard part of any experimental program at CUBRC, and is of key importance for post-test data quality analysis (correlation) and understanding particular phenomena seen in the data. All work during this effort was sponsored and paid for by the NASA Space Shuttle Program Office under the direction of the Orbiter Entry Aeroheating technical leadership.