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Innovative Scientific Solutions Inc. Air Force Research Lab. Simultaneous Measurements of Pressure and Deformation on a UCAV in the SARL. J. Crafton, S. Fonov, E. Jones, L. Goss V. Fonov Innovative Scientific Solutions Inc. C. Tyler Air Force Research Lab. Motivation: Shorten Design Cycle.
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Simultaneous Measurements of Pressure and Deformation on a UCAV in the SARL J. Crafton, S. Fonov, E. Jones, L. Goss V. Fonov Innovative Scientific Solutions Inc. C. Tyler Air Force Research Lab
Motivation: Shorten Design Cycle Model Design Numerical Prediction Rapid Prototype Build Model Pressure, Velocity, Skin Friction, Geometry Experimental Data Compare CFD & EFD AIAA-0035 AIAA-0440 AIAA-1028 Validate Numerical Code
Sensitivity to pressure • 5% per [psi] • Sensitivity to temperature • 0.5% per [K] • Ideal paint • temperature sensitivity independent of pressure
Uncertainty in PSP Measurements (Liu) • Model parameters • Temperature • Illumination (model movement & lamp stability) • Calibration • Photo-degradation & Sedimentation • Spectral content of excitation • Filter leakage • Sensitivity coefficients • Compute sensitivity and identify major sources • Temperature • Illumination
Probe 1 L1(T,P,I) signal Probe 2 L2(T,P,I) reference Illumination • Model movement/deformation • Lamp stability • Binary PSP • reference probe • Luminescence • Linear function of illumination • Ratio signal/reference
jet • Inclined Impinging Jet • Shocks, Expansions, Wall Jet • Cold region under jet • Recovery Temperature • Paint is not isothermal • Common in PSP experiments
Probe 1 L1(T,P,I) signal Probe 2 L2(T,P,I) reference Temperature • Temperature • model construction • metal isothermal • plastic/ceramic adiabatic • temperature changes all day • recovery temperature • Binary PSP • Use reference probe for temperature correction • Reference probe • Match temperature sensitivity of PSP • Ideal paint is very valuable here (FIB)
Binary FIB Paint • Temperature sensitivity • ~ 25 times less than FIB • Uncertainty • 50 Pa/K
Signal Channel -vs- Binary M = 0.4 = 20 0.4 psi 14 • Illumination error - 30% of scale - model displacement 12 psi
Low Speed PSP • System approach • Binary paint with very little temperature sensitivity • Stable illumination source (spectral content essential) • Single camera and filter switch • Average!!! • Post run Wind-off (capture any thermal profile) • Process on the mesh if you can (I recommend Sergey) • Model • Stiff model and mount (no movement if possible) • Isothermal materials • Tunnel • Open circuit tunnel (minimize temperature) • Dark and be consistent
1/24th Scale Car at 50 m/s AFIT Tunnel Binary FIB Data acquisition ~ 12 sec
Flow Low Speed PSP V=17 m/s NASA Ames (Dr. J. Bell) Binary FIB p (psi) 0.05 taps reference targets -0.4
UCAV Flow • 5 PDV data planes near wing/body junction • Mach 0.2 • free stream ~ 68 m/s • 20 angle of attack
UCAV in SARL Vortex from nose
UCAV in SARL Vortex from nose Breaking down Vortex from wing Body junction
UCAV Results • compare PSP to taps • sigma 0.16 psi demonstrated 0.005 psi • background noise • background • 7:00 AM 1000 • 12:00 AM 30000 • dynamic background • cloud noise? • shorten exposure time • more lamps • more interlaced backgrounds M = 0.4 = 20 = 0.16 psi
Model Deformation • Stereo view of the model • signal and reference camera • Markers with known positions • pressure taps or resection markers • Photogrammetry (Stereo PIV) • wind-on marker positions on bitmap • reconstruct physical location of each marker • yields 3 components of deformation • Binary PSP Stereo & Photogrammetry System • minimal impact on test • increase value pressure and geometry
Stereo Photogrammetry System • Calibration • wind-off markers • need a 3D field • Dynamic range • camera depth of field • Accuracy (Stereo PIV) • ~ 1/10 pixel in plane • ~ 1 pixel out of plane • Response time • Limited by camera
Model Deformation • Root to Tip deformation - d 0.4 in • Bulk displacement - 1.0 in • Improve spatial resolution - more markers - non-uniform paint • Improve frequency response - faster camera (limited) M = 0.4 = 20
Conclusions and Future Work • Demonstrated measurements of Pressure & Deformation • Developed integrated system using binary PSP hardware • Binary PSP • minimize errors due to illumination and temperature • extending PSP to lower speeds • Stereo Photogrammetry • utilized binary PSP images for displacement measurements • determined 3 components of model displacement • Future Work • Feed deformed geometry back to CFD • Tools for quick comparison of EFD/CFD