Supersonic wind tunnel testing of 0.813 m diameter Disk-Gap-Band parachutes is being conducted in the NASA Glenn Research Center (GRC) 10'x10' wind-tunnel. The tests are conducted in support of the Mars Science Laboratory Parachute Decelerator System development and qualification. Four percent of full-scale parachutes were constructed similarly to the flight-article in material and construction techniques. The parachutes are attached to a 4% scale MSL entry-vehicle to simulate the free-flight configuration. The parachutes are tested from Mach 2 to 2.5 over a Reynolds number (Re) range of 1 to 3 x 10 6 , representative of the MSL deployment envelope. Constrained and unconstrained test configurations are investigated to quantify the effects of parachute trim, suspension line interaction, and alignment with the capsule wake. The parachute is constrained horizontally through the vent region, to measure canopy breathing and wake interaction for fixed trim angles of 0 and 10 degrees from the velocity vector. In the unconstrained configuration the parachute is permitted to trim and cone, similar to the free-flight varying its alignment relative to the entry-vehicle wake. Test diagnostics were chosen to quantify parachute performance and to provide insight into the flow field structure. An in-line load cell provided measurement of unsteady and mean drag as a function of Mach and Re. Highspeed shadowgraph video of the upstream parachute flow field was used to capture bowshock motion and stand of distance. Particle image velocimetry of the upstream parachute flow field provides spatially and temporally resolved measurement velocity and turbulent statistics. Multiple high speed video views of targets placed in the interior of the canopy enable photo-grammetric measurement of the fabric motion in time and space from reflective. High speed video is also used to document the supersonic inflation and measure trim angle, projected area, and frequency of area oscillations.

The development of new active tip clearance control and structural health monitoring schemes in turbine engines and other types of rotating machinery requires sensors that are highly accurate and can operate in a high temperature environment. The use of a microwave sensor to acquire blade tip clearance and tip timing measurements is being explored at the NASA Glenn Research Center. The microwave blade tip clearance sensor works on principles that are very similar to a short range radar system. The sensor sends a continuous microwave signal towards a target and measures the reflected signal. The phase difference of the reflected signal is directly proportional to the distance between the sensor and the target being measured. This type of sensor is beneficial in that it has the ability to operate at extremely high temperatures and is unaffected by contaminants that may be present in turbine engines. The use of microwave sensors for this application is a new concept. Techniques on calibrating the sensors along with installation effects are not well quantified as they are for other sensor technologies. Developing calibration techniques and evaluating installation effects are essential in using these sensors to make tip clearance and tip timing measurements. As a means of better understanding these issues, the microwave sensors were used on a bench top calibration rig, a large axial vane fan, and a turbofan. Background on the microwave tip clearance sensor, an overview of their calibration, and the results from their use on the axial vane fan and the turbofan will be presented in this paper.

Supersonic wind-tunnel tests of 0.813 m disk-gap-band parachutes were conducted in a 10 10 ft cross section of a closed-loop wind tunnel. Four-percent-scale parachutes were attached to a 4%-scale Mars Science Laboratory (Viking-type) entry vehicle to simulate the free-flight configuration. The parachutes were tested from Mach 2 to 2.5 over a Reynolds number Re range of 2 10 5 to 1:3 10 6 , representative of the Mars flight deployment envelope. A constrained parachute configuration was investigated to quantify the effect of parachute trim angle with respect to alignment with the entry-vehicle wake. In the constrained configuration, the parachutes were supported at the vent, using a rod that restricted parachute translation along a single axis. This was investigated for fixed trim angles of 0 and 10 degrees from the velocity vector. In the unconstrained configuration, the parachute was permitted to translate as well as trim and cone, in a manner similar to free flight. Nonintrusive test diagnostics were selected. An in-line load cell provided measurement of unsteady and mean parachute normal force. High-speed shadowgraph video of the upstream parachute flowfield was used to capture bow-shock motion and standoff distance. Stereo particle image velocimetry of the flowfield upstream of the parachute provided spatially resolved measurements of all three velocity components. Multiple high-speed-video views were used to document the supersonic inflation, parachute trim angle, projected area, and frequency of area oscillations. In addition, reflective targets placed in the interior of the canopy enabled photogrammetric reconstruction of the canopy-fabric motion (in both time and space) from the high-speedvideo data. Nomenclatureor constructed diameter D p = projected diameter d = entry-vehicle diameter F D = axial drag force F D;RMS = axial rms drag M = Mach number m p = parachute mass q = freestream dynamic pressure Re = Reynolds number t = time t FI = time to full inflation t = nondimensional inflation time x=d = nondimensional trailing distance v = freestream velocity p = mass ratio ! AO = area oscillation frequency

Supersonic wind tunnel testing of Viking-type 0.8 m Disk-Gap-Band (DGB) parachutes was conducted in the NASA Glenn Research Center 10'x10' wind-tunnel. The tests were conducted in support of the Mars Science Laboratory Parachute Decelerator System development and qualification program. The aerodynamic coupling of the entry-vehicle wake to parachute flow-field is under investigation to determine the cause and functional dependence of a supersonic canopy breathing phenomenon referred to as area oscillations, characteristic of DGB's above Mach 1.5 operation. Four percent of full-scale parachutes (0.8 m) were constructed similar to the flight-article in material and construction techniques. The parachutes were attached to a 70-deg sphere-cone entry-vehicle to simulate the Mars flight configuration. The parachutes were tested in the wind-tunnel from Mach 2 to 2.5 in a Reynolds number range of 2x10 5 to 1x10 6 , representative of a Mars deployment. Three different test configurations were investigated. In the first two configurations, the parachutes were constrained horizontally through the vent region to measure canopy breathing and wake interaction for fixed trim angles of 0 and 10 degrees from the free-stream. In the third configuration the parachute was unconstrained, permitted to trim and cone, similar to free-flight (but capsule motion is constrained), varying its alignment relative to the entry-vehicle wake. Non-intrusive test diagnostics were chosen to quantify parachute performance and provide insight into the flow field structure. An in-line loadcell provided measurement of unsteady and mean drag. Shadowgraph of the upstream parachute flow field was used to capture bow-shock motion and wake coupling. Particle image velocimetry provided first and second order flow field statistics over a planar region of the flow field, just upstream of the parachute. A photogrammetric technique was used to quantify fabric motion using multiple high speed video cameras to record the location in time and space of reflective targets placed on the canopy interior. The experimental findings including an updated drag model and the physical basis of the area oscillation phenomenon will be discussed.

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