Flow instability induced by spiked bodies

Hiraki, Koju; Kleine, H.; Maruyama, Hirotaka; Hayashida, Tomohiro; Kitamura, Keiichi; Yonai, Jun; Nakajima, Takashi; Etoh, Goji

doi:10.1117/12.823751

Cited by 2 publications

(3 citation statements)

References 13 publications

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“…As already mentioned in [18], the air around the spike does not withstand the pressure of the incoming flow as the wider shock layer allows the high-pressure gas to escape around the shoulder of the cylinder. The flow then pushes the bow shock back towards the model and a conical flow pattern is formed once again at the tip of the spike (Figure 9).…”

Section: Resultsmentioning

confidence: 93%

“…Former studies about spike-tipped models pointed out [15][16][17][18] the interaction between the incoming free stream flow and the high-pressure region near the model, which could have an influence on upstream at the tip of the spike by displacing the boundary layer along the spike and subsequently inducing a large-scale instability of the flow. In this paper, the unsteady flow around a spiketipped model at Mach number 3 is studied.…”

Section: Introductionmentioning

confidence: 99%

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Reconstruction of the Unsteady Supersonic Flow around a Spike Using the Colored Background Oriented Schlieren Technique

Leopold¹,

Ota²,

Klatt³

et al. 2013

JFCMV

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In this paper, the improved Background Oriented Schlieren technique called CBOS (Colored Background Oriented Schlieren) is described and used to reconstruct the density fields of three-dimensional flows. The Background Oriented Schlieren technique (BOS) allows the measurement of the light deflection caused by density gradients in a compressible flow. For this purpose the distortion of the image of a background pattern observed through the flow is used. In order to increase the performance of the conventional Background Oriented Schlieren technique, the monochromatic background is replaced by a colored dot pattern. The different colors are treated separately using suitable correlation algorithms. Therefore, the precision and the spatial resolution can be highly increased. Furthermore a special arrangement of the different colored dot patterns in the background allows astigmatism in the region with high density gradients to be overcome. For the first time an algebraic reconstruction technique (ART) is then used to reconstruct the density field of unsteady flows around a spike-tipped model from CBOS measurements. The obtained images reveal the interaction between the free-stream flow and the high-pressure region in front of the model, which leads to large-scale instabilities in the flow.In this case, assuming that the flow is axially symmetrical, every projection perpendicular to the symmetry axis should look the same. Earlier studies by Ota et al. [14] showed that good reconstruction data can be obtained from 36 projection angles ranging from 0˚ to 175˚ with intervals of 5˚. This configuration leads to an underestimation for the density of about 7% even in regions with high gradients. For the reconstruction of the flow field 152  240  240 voxels are used, which corresponds to a

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Section: Resultsmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Reconstruction of the Unsteady Supersonic Flow around a Spike Using the Colored Background Oriented Schlieren Technique

Leopold¹,

Ota²,

Klatt³

et al. 2013

JFCMV

View full text Add to dashboard Cite

show abstract

“…Feszty et al [93,94] confirmed using the numerical simulations the findings of Kenworthy. A high quality flow visualization for pulsation mode can be found in [95]. Sahoo et al [66] confirmed experimentally that rounding the spike tip can change pulsation mode into oscillation one.…”

Section: Key Studies On Flow Unsteadiness Associated With Mechanical mentioning

confidence: 96%

Forebody shock control devices for drag and aero-heating reduction: A comprehensive survey with a practical perspective

Ahmed

Qin

2020

Progress in Aerospace Sciences

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One key feature that distinguishes the flowfield around vehicles flying in supersonic and hypersonic regimes is the bow shock wave ahead of forebody. The severe drag and aeroheating impacting these vehicles can be significantly reduced if the bow shock wave ahead of the vehicles forebodies is controlled to yield weaker system of oblique shocks. Benefits of forebody shock control include increasing flight ranges, economizing fuel consumption, reducing dead weights, and thermally protecting forebody structure and onboard equipment. Forebody shock control that has been widely studied since the early 1900s is achievable in numerous techniques that vary according to the mechanism of control. While some of these techniques have already been implemented in real systems, other techniques involve serious complications and tough trade-offs. The present paper is intended to serve as the first comprehensive survey on the field of forebody shock control devices. The objectives of the present paper are multifold. The paper categorizes the various forebody shock control devices in a physics-based manner, explains the underlying physics for each device, and surveys the key studies and state-of-the-art knowledge. The paper also addresses the existing gaps in knowledge, highlights the existing systems implementing these devices, and discusses the associated practical implementation issues and design-tradeoffs. 2. Structural devices, the mechanical spikes: 2.1. Principle of operation of mechanical spikes Drag and Aeroheating Reduction Devices Fluidic Devices Opposing jets Structural Devices Mechanical spikes Energetic Devices Energy deposition Basic devices Structural-Fluidic Devices Structural-Energetic Devices Hybrid devices

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Flow instability induced by spiked bodies

Cited by 2 publications

References 13 publications

Reconstruction of the Unsteady Supersonic Flow around a Spike Using the Colored Background Oriented Schlieren Technique

Reconstruction of the Unsteady Supersonic Flow around a Spike Using the Colored Background Oriented Schlieren Technique

Forebody shock control devices for drag and aero-heating reduction: A comprehensive survey with a practical perspective

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