Application of Mach-Zehnder interferometers for isolator shock trains

Takeshita, Taishi; Nakao, Shinichiro; Miyazato, Yoshiaki

doi:10.15240/tul/004/2019-1-006

Cited by 2 publications

(2 citation statements)

References 14 publications

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“…Rainbow schlieren pictures were taken with an exposure time of 1/8,000s and ISO 640. Takeshita et al [28] experimentally observed that a shock train with an incoming Mach number of 1.44 oscillates around its time-mean position with a dominant frequency of around 10Hz. Therefore, the exposure time of the present rainbow schlieren system should be short enough to freeze a shock train.…”

Section: Methodsmentioning

confidence: 99%

“…The error contains the precision error [44] only, but not the bias error since it is negligibly small when compared to the precision errors. The precision error is also affected significantly by density fluctuations caused by the unsteady behaviour of the shock train [28]. The red line shows that a successive sudden increase in the density is due to the presence of the successive shocks constituting the shock train.…”

Section: Flow Topology Of Shock Trainmentioning

confidence: 99%

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Quantitative flow diagnostics of shock trains by rainbow schlieren deflectometry

Takeshita

Fukunaga²,

Nakao³

et al. 2022

Aeronaut. j.

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A new measurement technique to reconstruct the density field of the shock-wave/boundary-layer interaction (SWBLI) in a confined duct is proposed. With this technique, it is possible to quantitatively capture in detail the structures of the density field both in the regions of the shock-systems in the central core and boundary-layer flows near the duct wall concurrently. The novel feature of the proposed technique is to make use of the schlieren images with the rainbow filters of the vertical and horizontal cutoff settings and then to reconstruct the two-dimensional density field integrated over the line-of-sight direction using the corresponding filter calibration curves. The proposed technique is applied for the first time to a shock train in a constant-area straight duct under the upstream condition of the shock train: the freestream Mach number is 1.42, the incoming boundary layer thickness normalised by the duct half height is 0.175, and the corresponding unit Reynolds number $Re/m$ is $2.99 \times 10^7$ m-1. The calculated isopycnic field depicts the streamwise and transverse density variations inside the shock train, the mixing region after the shock train, and the boundary-layer of the interaction region. This technique is shown to be capable of identifying the locations of shocks in a shock train more precisely than a conventional approach measuring the static pressure distribution along the duct wall. In addition, various quantitative visual representations such as a shadowgraphy and a bright-field schlieren can be extracted from the density field acquired by the present approach, and the spatial evolution of the shape and strength of each shock constituting the shock train as well as the boundary layer flow properties can be quantitatively clarified.

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Section: Methodsmentioning

confidence: 99%

Section: Flow Topology Of Shock Trainmentioning

confidence: 99%