Schlieren study of a sonic jet injected into a supersonic cross flow using high-current pulsed LEDs

Ella Giskes, Ruben A. Verschoof, Frans B. Segerink, Cornelis H. Venner

Research output: Contribution to journalArticleAcademic

40 Downloads (Pure)

Abstract

Benefiting from the development of increasingly advanced high speed cameras, flow visualization and analysis nowadays yield detailed data of the flow field in many applications. Notwithstanding this progress, for high speed and supersonic flows it is still not trivial to capture high quality images. In this study we present a Schlieren setup that uses pulsed LEDs with high currents (up to 18 Ampere) to increase the optical output to sufficient levels. The bright and short pulses, down to 130 nanoseconds, allow detailed and sharp imaging of the flow with a high spatial resolution adequate for supersonic flow. The pulse circuit and pulse width determination are explained in detail. As a test case we studied the near field of a 2 mm diameter sonic jet injected transversely into a supersonic cross flow. This is a model flow for fuel injection in scramjet engines, which is not yet fully understood. Owing to the high resolution and accuracy of the images produced by the newly developed system we prove the existence of a large (density) gradient wave traveling in the windward subsonic region between the Mach barrel and the bowshock, which hitherto was observed only in some numerical studies but not yet shown in experiments. Furthermore, we demonstrate with this Schlieren setup that time-correlated images can be obtained, with an interframe time of 2 microseconds, so that also flow unsteadiness can be studied such as the movement of shock waves and trajectories of vortices. The obtained results of the jet penetration height are presented as a power law correlation. The results of this study show that the designed setup using a low-cost LED and low-cost control system is a high potential option for application in visualization studies of high speed flows.
Original languageEnglish
Number of pages11
JournalarXiv.org
DOIs
Publication statusPublished - 28 Jun 2017

Fingerprint

cross flow
high current
light emitting diodes
supersonic flow
high speed
fuel injection
supersonic combustion ramjet engines
high speed cameras
high resolution
flow visualization
pulses
traveling waves
shock waves
near fields
flow distribution
pulse duration
penetration
spatial resolution
trajectories
vortices

Keywords

  • physics.flu-dyn

Cite this

@article{134e7486661d497a8fb8ad1931829e35,
title = "Schlieren study of a sonic jet injected into a supersonic cross flow using high-current pulsed LEDs",
abstract = "Benefiting from the development of increasingly advanced high speed cameras, flow visualization and analysis nowadays yield detailed data of the flow field in many applications. Notwithstanding this progress, for high speed and supersonic flows it is still not trivial to capture high quality images. In this study we present a Schlieren setup that uses pulsed LEDs with high currents (up to 18 Ampere) to increase the optical output to sufficient levels. The bright and short pulses, down to 130 nanoseconds, allow detailed and sharp imaging of the flow with a high spatial resolution adequate for supersonic flow. The pulse circuit and pulse width determination are explained in detail. As a test case we studied the near field of a 2 mm diameter sonic jet injected transversely into a supersonic cross flow. This is a model flow for fuel injection in scramjet engines, which is not yet fully understood. Owing to the high resolution and accuracy of the images produced by the newly developed system we prove the existence of a large (density) gradient wave traveling in the windward subsonic region between the Mach barrel and the bowshock, which hitherto was observed only in some numerical studies but not yet shown in experiments. Furthermore, we demonstrate with this Schlieren setup that time-correlated images can be obtained, with an interframe time of 2 microseconds, so that also flow unsteadiness can be studied such as the movement of shock waves and trajectories of vortices. The obtained results of the jet penetration height are presented as a power law correlation. The results of this study show that the designed setup using a low-cost LED and low-cost control system is a high potential option for application in visualization studies of high speed flows.",
keywords = "physics.flu-dyn",
author = "Ella Giskes and Verschoof, {Ruben A.} and Segerink, {Frans B.} and Venner, {Cornelis H.}",
note = "11 pages, 12 figures",
year = "2017",
month = "6",
day = "28",
doi = "10.1103/APS.DFD.2016.GFM.V0067",
language = "English",
journal = "arXiv.org",
publisher = "Cornell University",

}

Schlieren study of a sonic jet injected into a supersonic cross flow using high-current pulsed LEDs. / Giskes, Ella; Verschoof, Ruben A.; Segerink, Frans B.; Venner, Cornelis H.

In: arXiv.org, 28.06.2017.

Research output: Contribution to journalArticleAcademic

TY - JOUR

T1 - Schlieren study of a sonic jet injected into a supersonic cross flow using high-current pulsed LEDs

AU - Giskes, Ella

AU - Verschoof, Ruben A.

AU - Segerink, Frans B.

AU - Venner, Cornelis H.

N1 - 11 pages, 12 figures

PY - 2017/6/28

Y1 - 2017/6/28

N2 - Benefiting from the development of increasingly advanced high speed cameras, flow visualization and analysis nowadays yield detailed data of the flow field in many applications. Notwithstanding this progress, for high speed and supersonic flows it is still not trivial to capture high quality images. In this study we present a Schlieren setup that uses pulsed LEDs with high currents (up to 18 Ampere) to increase the optical output to sufficient levels. The bright and short pulses, down to 130 nanoseconds, allow detailed and sharp imaging of the flow with a high spatial resolution adequate for supersonic flow. The pulse circuit and pulse width determination are explained in detail. As a test case we studied the near field of a 2 mm diameter sonic jet injected transversely into a supersonic cross flow. This is a model flow for fuel injection in scramjet engines, which is not yet fully understood. Owing to the high resolution and accuracy of the images produced by the newly developed system we prove the existence of a large (density) gradient wave traveling in the windward subsonic region between the Mach barrel and the bowshock, which hitherto was observed only in some numerical studies but not yet shown in experiments. Furthermore, we demonstrate with this Schlieren setup that time-correlated images can be obtained, with an interframe time of 2 microseconds, so that also flow unsteadiness can be studied such as the movement of shock waves and trajectories of vortices. The obtained results of the jet penetration height are presented as a power law correlation. The results of this study show that the designed setup using a low-cost LED and low-cost control system is a high potential option for application in visualization studies of high speed flows.

AB - Benefiting from the development of increasingly advanced high speed cameras, flow visualization and analysis nowadays yield detailed data of the flow field in many applications. Notwithstanding this progress, for high speed and supersonic flows it is still not trivial to capture high quality images. In this study we present a Schlieren setup that uses pulsed LEDs with high currents (up to 18 Ampere) to increase the optical output to sufficient levels. The bright and short pulses, down to 130 nanoseconds, allow detailed and sharp imaging of the flow with a high spatial resolution adequate for supersonic flow. The pulse circuit and pulse width determination are explained in detail. As a test case we studied the near field of a 2 mm diameter sonic jet injected transversely into a supersonic cross flow. This is a model flow for fuel injection in scramjet engines, which is not yet fully understood. Owing to the high resolution and accuracy of the images produced by the newly developed system we prove the existence of a large (density) gradient wave traveling in the windward subsonic region between the Mach barrel and the bowshock, which hitherto was observed only in some numerical studies but not yet shown in experiments. Furthermore, we demonstrate with this Schlieren setup that time-correlated images can be obtained, with an interframe time of 2 microseconds, so that also flow unsteadiness can be studied such as the movement of shock waves and trajectories of vortices. The obtained results of the jet penetration height are presented as a power law correlation. The results of this study show that the designed setup using a low-cost LED and low-cost control system is a high potential option for application in visualization studies of high speed flows.

KW - physics.flu-dyn

U2 - 10.1103/APS.DFD.2016.GFM.V0067

DO - 10.1103/APS.DFD.2016.GFM.V0067

M3 - Article

JO - arXiv.org

JF - arXiv.org

ER -