Direct measurements of skin friction in complex supersonic flows

Novean, Michael; Schetz, Joseph A.; Bowersox, Rodney D. W.

doi:10.2514/6.1997-394

Cited by 13 publications

(5 citation statements)

References 6 publications

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“…The researchers concluded the balance worked well for this application, but they speculated that it would not be generally used, especially in wide temperature range. NASA Ames Research Center [22,23] carried out direct measurements of skin friction in hypersonic impulsive scramjet experiments, based on a balance using semiconductor strain gauges. The balance measured the wall shear stress in the range of 450-1320 Pa in a scramjet flowfield at Mach 12-16 in a shock tunnel.…”

Section: Semiconductor Strain Gaugementioning

confidence: 99%

Hypersonic aerodynamic force balance using temperature compensated semiconductor strain gauges

Qiu,

Yang,

Sun

et al. 2023

Adv. Aerodyn.

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Metal foil strain gauges remain the state-of-the-art transducers for wind tunnel balances. While strain gauge technology is very mature, piezoresistive semiconductor sensors offer alternatives that are worth exploring to assess their unique benefits, such as better strain resolution and accuracy, which would enable balances to be designed with higher factors to safety and hence longer fatigue lifetimes. A new three-component balance, based on temperature compensated semiconductor strain gauges, is designed, calibrated and tested in a hypersonic low density wind tunnel. The static accuracy of the semiconductor balance is calibrated better than 0.3% FS, and the dynamic accuracy of the balance is established using a HB-2 standard model in a Mach 12 hypersonic flow. Good experimental repeatability is confirmed to be better than 2.5% FS, and the effectiveness of the balance is demonstrated by comparing the forces and moments of measured data with computational fluid dynamics simulations, as well as reference wind tunnel results under similar conditions.

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Section: Semiconductor Strain Gaugementioning

confidence: 99%

Hypersonic aerodynamic force balance using temperature compensated semiconductor strain gauges

Qiu,

Yang,

Sun

et al. 2023

Adv. Aerodyn.

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“…A proposed solution to this problem was to fill the gap with a substance that would check this flow. Previous studies had tried using silicone rubber in the entire inner volume of the gage, but loss in gage resolution due to increased resistance forces limited further development [25].…”

Section: Approachmentioning

confidence: 99%

Study of rubber damped skin friction gages for transonic flight research

Sang

Schetz²

2002

40th AIAA Aerospace Sciences Meeting &Amp; Exhibit

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A non-intrusive direct-measuring skin friction device with a rubber RTV sheet over the surface of the floating head, gap and housing was developed for application in 3D, unsteady, transonic flight conditions. Design conditions required optimum gage performance at altitudes ranging from 15,000 to 45,000 feet, Mach numbers ranging from 0.6 to 0.99 resulting in shear values of 0.3 to 1.5 psf. under vibration conditions up to 8.0 g rms over a 15 -2,000 Hz frequency range. The gage consisted of a rubber RTV sheetcoated floating element attached to an aluminum cantilevered beam. A dual-axis, full bridge strain gage configuration was used with the application of semi-conductor strain gages to increase instrument sensitivity. The gage was studied with and without a viscous liquid (glycerin) fill in the housing. Vibration verification testing was performed at 1.0 g rms in the Virginia Tech modal analysis lab to ensure adequate damping performance over a 0 -3200 Hz frequency range. Tests revealed that the rubber RTV compound sheet provided adequate viscoelastic damping, with or without viscous liquid fill. Gage performance verification testing was performed on in the Virginia Tech supersonic wind tunnel at shear levels of τ w = 3.9 to 5.3 psf in a Mach 2.4 flow. Skin friction values in good agreement with previous testing and analytical predictions were obtained from the tests with adequate damping in the low vibration environment of the Virginia Tech supersonic wind tunnel. The gage proved robust as it survived repeated runs including the violent start and unstart processes typical of a supersonic, blowdown wind tunnel. Flight tests were performed at NASA Dryden Flight Research Center, with the gage mounted in a plate suspended below an F-15 aircraft. This provided a mildly 3D, turbulent boundary layer on a vibrating surface. The gage was tested without liquid fill in the gage cavity, and it performed satisfactorily in this high vibration environment. The gage demonstrated adequate damping and good robustness, surviving the complete flight test intact and remained fully operational. The sensor measured skin friction values 30%-50% higher than those predicted by indirect methods and analogies generally valid for 2D, steady flows. The gage indicated trends in skin friction values for different flight conditions in good agreement with the other methods. Possible reasons for the differences in numerical values are discussed in detail, including potential uncertainties in the gage output and limitations and uncertainties in the methods used for comparison. Finally, suggestions for further development of such gages are provided for flight test applications.iii ACKNOWLEDGEMENTS

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“…The gauge was tested to measure wall shear stress in the range of 450-1320 Pa in a high-enthalpy scramjet flow-field at Mach 12-16 in a shock tunnel, and the results were encouraging. Novean et al [6] used silicon rubber instead of oil for damping, and compared the output of oil-filled and rubber-filled gauges in a scramjet flow-field, simulating Mach 14 flight conditions with a test time of nearly 0.5 ms. The rubber-filled gauge was more sensitive to vibration with large oscillations in its signal, while both the gauges were sensitive to an axial pressure gradient.…”

Section: Introductionmentioning

confidence: 99%

A skin-friction balance for shock tunnel applications

Kshetrimayum¹,

Menezes²,

Yerramalli³

2021

Meas. Sci. Technol.

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An acceleration-compensated skin-friction balance based on the floating-head technique was developed to measure skin friction in a hypersonic impulse facility. The balance consisted of measurement and acceleration units, the outputs of which can be coupled using a full-Wheatstone bridge to obtain pure shear output. The working of the balance was tested on a flat plate model exposed to a laminar flow with Mach number, stagnation enthalpy and Reynolds number of 8.2, 0.65 MJ kg−1 and 2.9 × 106 m−1, respectively. The measured wall shear stress agreed reasonably well with that predicted by Reynolds analogy.

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Direct measurements of skin friction in complex supersonic flows

Cited by 13 publications

References 6 publications

Hypersonic aerodynamic force balance using temperature compensated semiconductor strain gauges

Hypersonic aerodynamic force balance using temperature compensated semiconductor strain gauges

Study of rubber damped skin friction gages for transonic flight research

A skin-friction balance for shock tunnel applications

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