Use of laser differential interferometry to study receptivity on a hemispherical nose at Mach 4

Salyer, Terry; Ranclall, Laura A.; Collicott, Steven H.; Schneider, Steven P.

doi:10.2514/6.1998-238

“…Among the advantages of the LDI over other nonintrusive techniques are its high sensitivity, good spatial resolution, and large bandwidth. [29][30][31][32][33] Smeets and George developed the first version of the LDI in 1973, with which they were able to resolve optical path length differences as small as λ/30, 000 over bandwidths between 100 Hz and 10 MHz. 22 Salyer developed a feedback-stabilized version of the LDI at Purdue University able to resolve minimum path length differences of λ/13, 000 at a bandwidth of 6 MHz.…”

Section: Ldi Developmentmentioning

confidence: 99%

“…This was an upgrade from the home-built photoreceivers that Salyer used for his research in the Purdue Quiet Flow Ludwieg Tube (PQFLT). [30][31][32][33] The function of this receiver is to subtract the photocurrent generated by the two photodiodes. By doing this, common-mode-noise (such as laser-intensity noise) that is present on both the reference and signal beams is canceled out and suppressed from the signal.…”

Section: Ldi Developmentmentioning

confidence: 99%

Starting Issues and Forward-Facing Cavity Resonance in a Hypersonic Quiet Tunnel

Juliano

¹

,

Segura

²

,

Borg

³

et al. 2008

38th Fluid Dynamics Conference and Exhibit

Self Cite

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AFOSR/NA Unclassified and Approved for Public Release M.S. thesis by Rodrigo Segura with development of LDI for Mach-6 quiet tunnel and measurements in Mach-4 quiet tunnel Laminar-turbulent transition is a pivotal factor for the design of hypersonic vehicles but the mechanisms that induce transition are not well understood. A laser differential interferometer (LDI) is a non-intrusive optical device that measures the optical path length difference between two laser beams. The LDI is a reliable calibrated instrument to assist the study of boundary layer instability-wave growth in hypersonic flow and has high sensitivity and frequency response. An LDI with a commercial balanced photodetector capable of detecting optical path length differences of lambda/21,000 from DC to 80 MHz was assembled and tested in the Purdue Quiet-Flow Ludwieg tube. Fluctuations in the subsonic region of a forward-facing cavity were measured with the LDI and compared to those detected with a Kulite pressure transducer at the base of the cavity. Predictions of self-resonating deep cavities were confirmed. The LDI was then adapted and transferred to the Boeing/AFOSR Mach-6 Quiet Tunnel. hypersonic boundary layer transition optical instrument supersonic cavity flow oscillations experiment Unclassified Unclassified Unclassified Unlimited 151 ii Este trabajo va dedicado a mi papá, mi mamá, mi hermano, y mi Dios. A ustedes les debo todo lo que soy. iii ACKNOWLEDGMENTS I want to thank my advisor, Professor Steven P. Schneider for building and managing the hypersonic wind tunnels at Purdue University and giving me the opportunity to work on this project. Had it not been for his vote of confidence, the LDI would sit in a drawer for years to come. Furthermore, his expertise and frankness helped me get through the difficulties encountered in this experimental research. I would also like to thank my committee members, Professors Steven H. Collicott and Anastasios S. Lyrintzis, their guidance and suggestions are appreciated. The machinists and technicians at the Purdue Aerospace Sciences Laboratory were extremely helpful during the course of the project. I thank them for their excellent craftsmanship and valuable technical assistance. I would like to express my special gratitude to Madeline Chadwell, Robin Snodgrass, and John Phillips all of whom went out of their way to assist me with unexpected experimental breakdowns on multiple occasions. Jerry Hahn and Jim Younts were also included in that crew. The office and information systems staff at the Aeronautical and Astronautical Engineering department at Purdue University also played an important role. Linda Flack's timely reminders made the logistics of my academic life easy. I would like to give special thanks to Joan Jackson; she made me laugh and was patient and helpful even when I demanded her help on rather short notice. Joe Kline's technical assistance is appreciated. A great deal of contribution came from my fellow researchers.

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“…Among the advantages of the LDI over other nonintrusive techniques are its high sensitivity, good spatial resolution, and large bandwidth [14][15][16][17][18]. All of these make it a fine instrument to analyze the flow in the PQFLT.…”

Section: Motivation and Backgroundmentioning

confidence: 99%

“…Salyer characterized the perturbation profile across the shock and compared it with the LDI results. The laser system used to generate the laser perturbation in the work done by Salyer [15][16][17][18], Schmisseur [21], and Ladoon [22,23] could not be readily resurrected for this project, so it could not be used to test the performance of the LDI.…”

Section: Motivation and Backgroundmentioning

confidence: 99%

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Oscillations in a Forward-Facing Cavity Measured Using Laser-Differential Interferometry in a Hypersonic Quiet Tunnel

Segura¹

2007

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AFOSR/NAUnclassified and Approved for Public Release M.S. thesis by Rodrigo Segura with development of LDI for Mach-6 quiet tunnel and measurements in Mach-4 quiet tunnel Laminar-turbulent transition is a pivotal factor for the design of hypersonic vehicles but the mechanisms that induce transition are not well understood. A laser differential interferometer (LDI) is a non-intrusive optical device that measures the optical path length difference between two laser beams. The LDI is a reliable calibrated instrument to assist the study of boundary layer instability-wave growth in hypersonic flow and has high sensitivity and frequency response. An LDI with a commercial balanced photodetector capable of detecting optical path length differences of lambda/21,000 from DC to 80 MHz was assembled and tested in the Purdue Quiet-Flow Ludwieg tube. Fluctuations in the subsonic region of a forward-facing cavity were measured with the LDI and compared to those detected with a Kulite pressure transducer at the base of the cavity. Predictions of self-resonating deep cavities were confirmed. The LDI was then adapted and transferred to the Boeing/AFOSR Mach-6 Quiet Tunnel. to give special thanks to Joan Jackson; she made me laugh and was patient and helpful even when I demanded her help on rather short notice. Joe Kline's technical assistance is appreciated.A great deal of contribution came from my fellow researchers.

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Development of a Mach-6 Quiet-Flow Ludwieg Tube for Transition Research

Schneider

¹

2000

Laminar-Turbulent Transition

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Use of laser differential interferometry to study receptivity on a hemispherical nose at Mach 4

Cited by 14 publications

References 15 publications

Starting Issues and Forward-Facing Cavity Resonance in a Hypersonic Quiet Tunnel

Starting Issues and Forward-Facing Cavity Resonance in a Hypersonic Quiet Tunnel

Oscillations in a Forward-Facing Cavity Measured Using Laser-Differential Interferometry in a Hypersonic Quiet Tunnel

Development of a Mach-6 Quiet-Flow Ludwieg Tube for Transition Research

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