Direct measurements of skin friction in a scramjet combustor

DeTurris, Dianne; Schetz, Joseph A.; Hellbaum, R. F.

doi:10.2514/6.1990-2342

Cited by 14 publications

(10 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Both foil and semi-conductor strain gages have their relative advantages and disadvantages for this application. 45,46,47 Also, current pressure sensor designs are not able to make accurate high-speed measurements in harsh environments, including high temperature, high Mach number flows which can cause ionization of the gas. Currently, measurements in such an environment are made through pressure taps that protect the sensor, but the process greatly reduces the frequency response.…”

Section: Motivation For Employing Fiber Opticsmentioning

confidence: 99%

“…91,92,93,94 Attached to the beam were two Luna EFPI fiber optic strain sensors, as pictured in Figure 97. The concept was to construct a skin friction sensor as close as possible to previously fabricated conventional strain gage designs that have been successful.…”

Section: Version 1 Skin Friction Sensormentioning

confidence: 99%

“…1 In fact, Schetz's research group has produced a series of skin friction sensors based on strain gages mounted to the cantilever beam in a non-nulling arrangement. 21,22,23 As with any sensor, new design concepts take advantage of more sensitive transducing technology as it evolves. In the current study, the sensing technology has moved to fiber optics, allowing a design principle based on deflection instead of strain, which is new in non-nulling cantilever beam designs.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Development of fiber optic aerodynamic sensors for high Reynolds number supersonic flows

Pulliam¹,

Schetz²

2001

39th Aerospace Sciences Meeting and Exhibit

View full text Add to dashboard Cite

Aerospace Engineering (ABSTRACT)The purpose of the project was to examine fiber optic sensors for the measurement of pressure, skin friction, temperature, and heat flux in high Reynolds number, supersonic flow. Using a standard fiber optic signal conditioning unit (specifically a broadband interferometric system using spectra), the work centered around determining under what conditions these sensors will work effectively and quantifying the total system limitations.An interferometric-based, fiber optic skin friction sensor was developed for the measurement of wall shear stress in complex, supersonic flows. This sensor type was tested successfully in laminar, incompressible flow, and supersonic flow up to Mach 1.92, Mach 2.4 and 3.0 flow, in which the sensor operated with varying success. A micromachined, fiber optic pressure sensor was also tested in these supersonic conditions, also with varying success. The accurate operation of these sensors was found to be tied to the flow conditions and the fiber optic, signal processing system.A correlation was found to exist between the energy of the flow, either through its dynamic pressure or through external disturbances such as shocks or separation, and the noise in the signals, expressed by the variance of the gap estimate, for the pressure and skin friction sensors in these flows. The energy of the flow couples with the mechanical properties of the sensor reducing the fringe contrast of the signal used by the optical signal processing system to determine a gap estimate. As the energy of the flow is increased and the sensor is excited, the fringe contrast is reduced. A practical limit of a normalized fringe contrast of 0.10 was found for producing accurate gap estimates in real flows. A consequence is that there is a limit to the dynamic pressure of the flow for the sensors to operate accurately, which is demonstrated by the varying success of the supersonic wind tunnel tests. This correlation is sensor specific, meaning that sensors can be designed to operate successfully in any flow. Also, the signal processing system, which forms the other end of the total system, could be improved to allow accurate measurements with the current sensors.iii

show abstract

Section: Motivation For Employing Fiber Opticsmentioning

confidence: 99%

Section: Version 1 Skin Friction Sensormentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Development of fiber optic aerodynamic sensors for high Reynolds number supersonic flows

Pulliam¹,

Schetz²

2001

39th Aerospace Sciences Meeting and Exhibit

View full text Add to dashboard Cite

show abstract

“…and G2 ( , ,y) =F3 (4, y) M (4) + F4 (4, y) M * (4) exp (-j 2 mkF,),( 1 (31) where the upper-case letters indicate one-dimensional Fourier transforms. Next, applying the onedimensional algorithm in the y direction on the image pair in Eqs.…”

Section: Two-dimensional Interpolationmentioning

confidence: 99%

United States Air Force Summer Research Program -- 1993. Volume 5A. Wright Laboratory

Moore¹,

Barnard²,

Cone³

et al. 1993

View full text Add to dashboard Cite

“…Since then, they have been used in many different facilities, including high-enthalpy scramjet wind tunnel tests 24,25 , extremely shortduration impulse wind tunnel tests 26,27 , and transonic flight tests summarizes the general methods available for measuring skin friction discussed above, both direct and indirect, and lists the relative advantages and disadvantages of each.…”

mentioning

confidence: 99%

Development and Ground Testing of Direct Measuring Skin Friction Gages for High Enthalpy Supersonic Flight Tests

Smith

2002

22nd AIAA Aerodynamic Measurement Technology and Ground Testing Conference

View full text Add to dashboard Cite

Aerospace Engineering (ABSTRACT)A series of direct-measuring skin friction gages were developed for a high-speed, high-temperature environment of the turbulent boundary layer in flows such as that in supersonic combustion ramjet (scramjet) engines, with a progression from free-jet ground tests to a design for an actual hypersonic scramjet-integrated flight vehicle. The designs were non-nulling, with a sensing head that was flush with the model wall and surrounded by a small gap. Thus, the shear force due to the flow along the wall deflects the head, inducing a measurable strain. Strain gages were used to detect the strain. The gages were statically calibrated using a direct force method. The designs were verified by testing in a well-documented Mach 2.4 cold flow. Results of the cold-flow tests were repeatable and within 15% of the value of C f estimated from simple theory. The first gage design incorporated a cantilever beam with semiconductor strain gages to sense the shear on the floating head. Cooling water was routed both internally and around the external housing in order to control the temperature of the strain gages. This first gage was installed and tested in a rocket-based-combined-cycle (RBCC) engine model operating in the scramjet mode. The free-jet facility provided a Mach 6.4 flow with P 0 = 1350 psia (9310 kPa) and T 0 = 2800 °R (1555 °K). Local wall temperatures were measured between 850 and 900 °R (472-500 °K). Output from the RBCC scramjet tests was reasonable and repeatable. A second skin friction gage was designed for and tested in a wind tunnel model of the Hyper-X flight vehicle scramjet engine. These unsuccessful tests revealed the need for a radically different skin friction gage design.The third and final skin friction gage was specifically developed to be installed on the Hyper-X flight vehicle. Rather than the cantilever beam and semiconductor strain gages, the third skin friction gage made use of a flexure ring and metal foil strain gages to sense iii the shear. The water-cooling and oil-fill used on the previous skin friction sensors were eliminated. It was qualified for flight through a rigorous series of environmental tests, including pressure, temperature, vibration, and heat flux tests. Finally, the third skin friction gage was tested in the Hyper-X Engine Model (HXEM), a full-scale-partial-width wind tunnel model of the flight vehicle engine. These tests were conducted at Mach 6.5 enthalpy with P 0 = 555 psia (3827 kPa) and h 0 = 900 Btu/lb m in a freejet facility. The successful testing in the wind tunnel scramjet model provided the final verification of the gage before installation in the flight vehicle engine. The development, testing, and results of all three skin friction gages are discussed.

show abstract

Direct measurements of skin friction in a scramjet combustor

Cited by 14 publications

References 6 publications

Development of fiber optic aerodynamic sensors for high Reynolds number supersonic flows

Development of fiber optic aerodynamic sensors for high Reynolds number supersonic flows

United States Air Force Summer Research Program -- 1993. Volume 5A. Wright Laboratory

Development and Ground Testing of Direct Measuring Skin Friction Gages for High Enthalpy Supersonic Flight Tests

Contact Info

Product

Resources

About