Boundary Layer Transition Flight Experiment Overview and In Situ Measurements

Abstract

In support of the Boundary Layer Transition Flight Experiment (BLT FE) Project, a manufactured protuberance tile was installed on the port wing of Space Shuttle Orbiter Discovery for the flights of STS-119 and STS -128. Additional instrumentation was also installed in order to obtain more spatially resolved measurements downstream of the protuberance. This paper provides an overview of the BLT FE Project, including the project history, organizations involved, and motivations for the flight experiment. Significant efforts were made to place the protuberance at an appropriate location on the Orbiter and to design the protuberance to withstand the expected environments. Efforts were also extended to understand the as-fabricated shape of the protuberance and the thermal protection system tile configuration surrounding the protuberance. A high-level overview of the in-situ flight data is presented, along with a summary of the comparisons between pre-and post-flight analysis predictions and flight data. Comparisons show that predictions for boundary layer transition onset time closely match the flight data, while predicted temperatures were significantly higher than observed flight temperatures.

The Hythirm Project: Flight Thermography of the Space Shuttle During Hypersonic Re-Entry

“…8) and STS-128 (Fig. 10) were associated with Discovery which was configured with a "speed bump" built into a modified tile on the port wing to deliberately disrupt windward surface airflow -and promote transition to turbulence at high Mach numbers 1 . …”

The Expanding Role of Applications in the Development and Validation of CFD at NASA

“…As a result of this type of forward thinking, boundary layer transition experiments have recently been performed on the Space Shuttle 8,9 as it reenters the atmosphere. Instrumentation has also been added to the flight manifest of the Mars Science Laboratory entry vehicle to measure heatshield performance parameters as it enter the Martian atmosphere 10 .…”

Design and Implementation of the Boundary Layer Transition Flight Experiment on Space Shuttle Discovery

“…The entry data from BLT was reviewed by analysts and the flight experiment was determined to be a success. 6 Based on the data review, it was decided by the team, and with the concurrence of the Space Shuttle Program that a second flight utilizing a taller (0.35 inch) protuberance would provide engineers with data about boundary layer transition behavior approaching Mach 18 . From a processing perspective, this required the removal and replacement of several tiles in support of a taller protuberance.…”

“…For the first flight, the protuberance measured 0.25 inches tall and 4.0 inches long. 6 There was a thermocouple installed in the fin of the protuberance itself (Figure 1) which recorded what was expected to be the peak temperature of the experiment. The two tiles adjacent to the protuberance (V880-191011-040 & V880-191011-041) as well as the V880-191011-036 were removed and replaced in order to bolster the thermal capabilities in the area.…”

“…Fourth, an area had to be chosen that could support the installation of the Thermocouple Reference Junction (TRJ), a device that allows the input of ten thermocouples. 6 The Thermal Protection System (TPS) is the only system on the Space Shuttle Orbiter that does not have a redundant backup. It is also responsible for dissipating all of the re-entry heating, thus protecting the underlying airframe structure.…”