The Boundary Layer Transition (BLT) experiment involves the use of ten modified tiles, equipped with thermocouples (indicate a temperature change based on voltage between a junction of two different metals), placed on the bottom of Space Shuttle Discovery?s left wing. One tile is also equipped with a protuberance (specially modified speed bump) to study the characteristics of how the airflow is tripped from laminar (smooth) to turbulent (rough) during re-entry. This experiment will improve understanding of the parameters associated with re-entering the atmosphere and including the significant heat increase caused by turbulent boundary layer flow.Principal Investigator(s)
United Space Alliance, Cape Canaveral, FL, United States
Jacobs Engineering, Houston, TX, United States
NASA Ames Research Center, Moffett Field, CA, United States
Boeing, Huntington Beach, CA, United States
Kennedy Space Center, , FL, United States
Langley Research Center, Hampton, VA, United States
National Aeronautics and Space Administration (NASA)Sponsoring Organization
Human Exploration and Operations Mission Directorate (HEOMD)Research Benefits
Information PendingISS Expedition Duration:
October 2008 - October 2009Expeditions Assigned
18,19/20Previous ISS Missions
The Boundary Layer Transition (BLT) experiment was first introduced on ISS Expedition 18.
Two Shuttle missions have included the BLT implementation. During STS-119, a 0.25 inch (6.4 mm) speed bump was installed on Discovery. During STS-128, a 0.35 inch (9.6 mm) speed bump was installed on Discovery. Flight measurements indicated that boundary layer transition occurred near Mach 15 and 17.5 during STS-119 and STS-128, respectively. Downstream turbulent temperature increases of several hundred degrees Fahrenheit were recorded during the turbulent heating duration of the entry. As part of efforts to provide technical documentation of results and studies related to the collaborative NASA and Air Force efforts on boundary layer transition, twenty three technical publications were presented at the January 2010 AIAA Aerospace Sciences Meeting.
The data gathered from the BLT experiment will be utilized to support analytical computer modeling and design efforts for the Space Shuttle and NASA?s next generation spacecraft.Earth Applications
The BLT investigation provides scientists and engineers with the incredible opportunity to demonstrate how NASA is working to understand spaceflight better and an opportunity to successfully apply what has been learned to improve space vehicles.
The Boundary Layer Transition DTO will involve the use of ?integrated TPS and MADS instrumentation (designed) to fly with a fixed protuberance tile with a height of 0.25? to initiate BLT.Operational Protocols
Ten modified tiles are part of the flight experiment, including a tile with a raised surface known as the protuberance tile. All ten tiles have a thermocouple built in, which acts like a thermometer. The temperature data during Orbiter entry is collected by these ten thermocouples. One of the tiles with a thermocouple is mounted in front of the protuberance tile to measure the normal temperature in the regular airflow.
The STS-119 Boundary Layer Transition (BLT) Flight Experiment was successful in obtaining BLT onset data near Mach 16 and turbulent heating data after Mach 16 with a 0.25" tile protuberance downstream of the port landing gear door. Flight hardware performance and thermocouple data was excellent and no anomalies were identified. Initial flight data reviews indicated high confidence for implementing a larger protuberance height on STS-128.