Response of an oblique shock train to downstream periodic pressure perturbations

Cheng, Chuan; Wang, Chengpeng; Cheng, Keming

doi:10.1177/0954410017727028

Cited by 12 publications

(4 citation statements)

References 38 publications

(65 reference statements)

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“…Meanwhile, the vortices generated by the shear layer of the separation bubble travel downstream and have a direct influence on the motion of the downstream shocks. Similarly, other studies [193][194][195] demonstrate that pressure perturbations travel upstream to the leading-edge shock train through the subsonic flow region near the wall, triggering shock fluctuations. Leonard and Narayanaswamy [196] investigated the shock dynamics in a two-dimensional axisymmetric isolator with an incoming Mach number of 3.0.…”

Section: Effect Of Back Pressurementioning

confidence: 62%

Aerodynamic Instabilities in High-Speed Air Intakes and Their Role in Propulsion System Integration

Philippou,

Zachos,

MacManus

2024

Aerospace

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High-speed air intakes often exhibit intricate flow patterns, with a specific type of flow instability known as `buzz’, characterized by unsteady shock oscillations at the inlet. This paper presents a comprehensive review of prior research, focused on unraveling the mechanisms that trigger buzz and its implications for engine stability and performance. The literature survey delves into studies concerning complex-shaped diffusers and isolators, offering a thorough examination of flow aerodynamics in unstable environments. Furthermore, this paper provides an overview of contemporary techniques for mitigating flow instability through both active and passive flow control methods. These techniques encompass boundary layer bleeding, the application of vortex generators, and strategies involving mass injection and energy deposition. The study concludes by discussing future prospects in the domain of engine-intake aerodynamic compatibility. This work serves as a valuable resource for researchers and engineers striving to address and understand the complexities of high-speed air induction systems.

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Section: Effect Of Back Pressurementioning

confidence: 62%

Aerodynamic Instabilities in High-Speed Air Intakes and Their Role in Propulsion System Integration

Philippou,

Zachos,

MacManus

2024

Aerospace

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“…Experiments were performed in a blowdown-type supersonic wind tunnel at Nanjing University of Aeronautics and Astronautics. The supersonic tunnel was set to produce a freestream Mach number of 2.7 in the test section, 24 and the Reynolds number based on the throat height ranged from 0.5 to 1.2 ×10 7 . The stagnation pressure P 0 upstream could be set to a maximum of 800 kPa, while the downstream pressure is open to the atmosphere.…”

Section: Experimentationmentioning

confidence: 99%

Asymmetry of oblique shock train and flow control

Zhang,

Cheng,

Zhang

et al. 2024

Proceedings of the Institution of Mechanical Engineers, Part G:

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An oblique shock train generally forms an asymmetric structure in a Mach-2.7 flow field within a duct. To study the flow structure and interaction between oblique shock trains and upstream shocks, a ramp with equal width was installed inside a Mach-2.7 straight duct to generate an incident shock and an oblique shock train interaction. A Schlieren system, transient pressure measurements and particle image velocimetry were used to capture quantitative and qualitative shock structure information. Results show that the asymmetric separation deflection of the oblique shock train occurs randomly in the symmetrical straight duct. The separation deflection of the oblique shock train was steady with upstream shock interactions. Under backpressure conditions, the rate of movement of the oblique shock train increases rapidly when it passes through the separation regions generated by the ramp, and the deflection direction of the asymmetric separation may switch. Based on the characteristics of the oblique shock train and upstream shock interaction, a flow control method was used to generate asymmetric upstream flow conditions, providing active control of the oblique shock train deflection direction.

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“…The complex shock-system was shown to be influenced by upstream-propagating acoustic waves from regions of flow separation, and downstream-travelling vortices shed from the separation bubble. The wind tunnel tests of Cheng et al (2017) looked at the response of an oblique shock-train to downstream pressure perturbations at Mach 2.7. The oblique shock-train was shown to be sensitive to downstream pressure perturbations within the separation bubble and subsonic shear layer.…”

Section: Introductionmentioning

confidence: 99%

Shock-Wave/Boundary-Layer Interactions in Transitional Rectangular Duct Flows

Lusher

Sandham

2020

Flow Turbulence Combust

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Shock-wave/boundary-layer interactions (SBLI) are an important feature of high-speed gas dynamics. In many numerical studies of SBLI span-periodicity is assumed to reduce computational complexity. However, span-periodicity is not a valid assumption for aeronautical applications such as supersonic engine intakes where lateral confinement leads to highly three-dimensional behaviour. In this work transitional oblique SBLI are simulated for a rectangular duct with a sg = 5 • shock generator ramp at Mach 2. The baseline configuration is a duct with an aspect ratio of 0.5. Time-dependent disturbances are added to the base laminar flow via wall localised blowing/suction strips to obtain intermittent transition upstream of the SBLI. Two forcing configurations are evaluated to assess the response of the SBLI to different tripping locations. The transition is observed to develop first in the low-momentum corners of the duct and spread out in a wedge shape. The central separation bubble is seen to react dynamically to oncoming turbulent spots, shifting laterally across the span. While instantaneous corner separations do occur, the time-averaged corner flow remains attached. Comparisons to a one-to-one aspect ratio duct show that the SBLI is heavily dependent on aspect ratio; the wider duct exhibited significantly larger regions of flow-reversal due to a strengthened interaction.

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Response of an oblique shock train to downstream periodic pressure perturbations

Cited by 12 publications

References 38 publications

Aerodynamic Instabilities in High-Speed Air Intakes and Their Role in Propulsion System Integration

Aerodynamic Instabilities in High-Speed Air Intakes and Their Role in Propulsion System Integration

Asymmetry of oblique shock train and flow control

Shock-Wave/Boundary-Layer Interactions in Transitional Rectangular Duct Flows

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