Preparations for Tomographic Background-Oriented Schlieren Measurements in the 11-by 11-Foot Transonic Wind Tunnel
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Joshua M Weisberger↗
Engineering topics
Jonathon D Ponder
Publications and source records attributed to Jonathon D Ponder.
Advancements in Force and Angle Measurement by the NFMTC
The National Force Measurement Technology Capability (NFMTC) is a nationwide partnership established in 2008 and sponsored by NASA’s Aeronautics Evaluation and Test Capabilities (AETC) project to maintain and further develop force and angle measurement capabilities primarily for NASA’s ground test facilities. One of the NFMTC’s primary objectives is to develop new force and angle measurement capabilities to meet the needs of researchers testing in NASA’s ground test facilities. This work will highlight several new capabilities that are either at or near operational readiness. A new six-component flow-through balance was designed and fabricated to support an upcoming retropropulsion test campaign at the NASA Langley Unitary Plan Wind Tunnel. The balance employs membranes in place of bellows, which have historically been used, and passes the flow through load bearing parts of the balance. Flow through the balance is optimized via the addition of flow guides, which are manufactured as separate parts, and attached to the balance. Calibration of this new flow-through balance demonstrates that it can suitably characterize the load and pressure ranges it was designed for, which provides aero researchers a new tool to directly measure retropropulsion performance of powered descent vehicles. Balances used in NASA’s ground test facilities are typically either single-piece balances or floating-frame balances. Historically, these two types of balances have generally used different front-end (model) attachments. Single-piece balances generally have a cylindrical front end that is forward of any measuring sections and at a reduced diameter relative to the balance outer diameter. Floating-frame balances generally have front end fits that extend over one or more measuring sections and that engage at the balance outer diameter. Recently, the NFMTC fabricated a single-piece balance with a front end fit that is compatible with the hardware used to calibrate floating-frame balances. Calibration results evaluating this front end fit will be presented. From a recent survey of angle measurement needs, the development of smaller angle measurement packages was identified as one area of improvement. Micro-electromechanical systems (MEMS) are continually being refined to provide high performance accelerometers that are a fraction of the volume of the quartz flexure based accelerometers that are standard in wind tunnels. A survey of commercial off-the-shelf MEMS accelerometers was conducted, and it identified the Safran Colibrys MS lines to be of adequate performance. Single-axis test boards and tri-axis rigid-flex production boards were designed and fabricated with a volume of approximately .18 cubic inches. The boards were designed to provide all the necessary conditioning for the MEMS accelerometers at levels to meet or exceed all requirements for the MS line sensors. Preliminary testing of these assembled sensor packages has demonstrated acceptable performance for wind-tunnel angle measurement. Several new rotating balances are at various stages of completion for NASA Glenn Research Center’s fan drive rigs. These balances provide direct measurement of thrust and torque of a driven fan or fan section to provide an estimate of fan efficiency and net thrust. Three two-component balances have been recently completed, and one six-component balance is in active development. A custom rotating telemetry system has been developed to support testing with these balances, and the telemetry system is integrated into the forward end of each one. The telemetry system is designed to remove mechanical sliprings by using an optical ethernet-based slipring for data transmission.
Force measurement↗
Development of the NASA Mini/MEMS Tri-Axis Sensor System
This manuscript details the development of a reduced volume attitude sensor developed at NASA. This new sensor uses MEMs based accelerometers to reduce the volume when compared to current sensors used in wind-tunnel models. Our team has designed, fabricated, and evaluated the Mini/MEMs Tri-Axis Sensor System (MTASS). The current MTASS design accommodates three tactical-grade accelerometers into the volume of a single axis accelerometer that is currently used. This arrangement allows for the estimation of model pitch and roll angles. Static testing of the MTASS demonstrated angle accuracies within ±0.01° for both pitch and roll.
angle measurement↗
Development of the NASA Mini/MEMS Tri-Axis Sensor System
This manuscript details the development of a reduced volume attitude sensor developed at NASA. This new sensor uses MEMs based accelerometers to reduce the volume when compared to current sensors used in wind-tunnel models. Our team has designed, fabricated, and evaluated the Mini/MEMs Tri-Axis Sensor System (MTASS). The current MTASS design accommodates three tactical-grade accelerometers into the volume of a single axis accelerometer that is currently used. This arrangement allows for the estimation of model pitch and roll angles. Static testing of the MTASS demonstrated angle accuracies within ±0.01° for both pitch and roll.
angle measurement↗
Improvements to Calibration Modeling of a Tri-Axial Accelerometer Using Response Surface Methods
Aerodynamic ground test facilities require precision attitude measurements to support fundamental research and aerodynamic vehicle characterization. Accelerometers are used as one solution for measuring test article attitude. Several wind-tunnel facilities experience elevated temperatures during sustained testing of approximately 38°C (100°F) and extremes up to 149°C (300°F). Accelerometer thermal corrections are required to maintain attitude measurement accuracy during elevated temperature tunnel conditions. This manuscript details characterization of non-linear and thermal effects of the Mini/MEMs Tri-Axis Sensor System (MTASS) developed at NASA. Non-linear effects are characterized using a two-axis index head, and temperature effects are characterized using a metallic cube in a thermal chamber. The results show a significant decrease in back-computed residuals for room temperature and elevated temperatures experiments.
Accelerometer↗