Experimental Investigation of the Unstart Process of a Generic Hypersonic Inlet

Tan, Hui-Jun; Li, Liu-Gang; Yao, Wen; Zhang, Qi-Fan

doi:10.2514/1.j050200

Cited by 103 publications

(21 citation statements)

References 12 publications

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“…It is worth to note that the pressure drops and oscillates randomly and weakly at x ¼ 120 mm. This phenomenon was termed as the non-oscillatory violent flow pattern in Tan et al 14 The frequencies corresponding to different plug positions are listed in Table 3.…”

Section: Resultsmentioning

confidence: 99%

Mathematical modeling and characteristic analysis of scramjet buzz

Chang

Wang

Bao

2014

Proceedings of the Institution of Mechanical Engineers, Part G:

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Buzz is an important issue for a scramjet engine. A mathematical model of buzz oscillations is necessary for control system design. Control-oriented models of hypersonic vehicle propulsion systems require a reduced-order model that is accurate to some extent but requires less than a few seconds of computational time. To achieve this goal, a reducedorder model of buzz oscillations for a scramjet engine is built by introducing the modeling idea of Moore-Greitzed model for compressors. The introduction of characteristic lines avoids the complex interactions in hypersonic inlet, such as shock-shock interactions and shock-boundary layer interaction. And the inlet characteristics are obtained from the pressure signal of combustor. Based on the established buzz model, we can predict the inlet performance, characterize the stability margin of inlet, reflect the oscillatory characteristics of inlet buzz including the dominant amplitude and frequency and describe the transition process of inlet buzz.

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Section: Resultsmentioning

confidence: 99%

Mathematical modeling and characteristic analysis of scramjet buzz

Chang

Wang

Bao

2014

Proceedings of the Institution of Mechanical Engineers, Part G:

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“…The backpressure increases as the shock train moves upstream, but the increment speed of backpressure does not show any discernible effects on the propagation velocity of unstart shock [12]. Tan [14] in 2011 used surface pressure distributions to investigate the unstart process of a generic hypersonic inlet and try to predict inlet unstart. Next year, Tan [3] illustrated dynamic mechanism for the shock train oscillation by investigation of shock train dynamic characteristics with complex background waves.…”

Section: Introductionmentioning

confidence: 99%

Mechanism and Prediction for Occurrence of Shock Train Sharp Forward Movement

Chang

Zhou

et al. 2015

51st AIAA/SAE/ASEE Joint Propulsion Conference

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Numerical simulation was conducted using commercial CFD software FLUENT to study the influence of inner flow structures on the motion characteristics of separation oblique shock train caused by back pressure. Simulation results indicate there is a separation point of boundary layer at head of shock train. The separated flow expands in isolator and leads to movements of shock train. With shock train moving forward in isolator, the leading edge of shock train passes through the peaks and valleys of pressure along the forward path. As the pressure gradient at the separation point switches between positive and negative gradients, the state properties of shock train movements transform between slow forward movement and sudden sharp forward movement. The sudden sharp forward movement of shock train always occurs when the separation point surmounts reflection points of the background wave system, which implies that the forward motion characteristics of shock train is related to the background flow structures. So the occurrence of sharp forward movement of shock train can be predicted from the flow structures of a fully started state. Nomenclature M a = Mach number P ∞ = Freestream static pressure T ∞ = Freestream Static temperature P 0 = Total pressure p = Static pressure T 0 = Total temperature

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“…As a consequence, there is loss of engine thrust, significantly increased loads, and intense oscillatory flow. [1][2][3] In this paper we will discuss how the shock train responds to periodic forcing. That is, we will study the dynamics of the shock train when the back pressure is oscillated with magnitudes low enough that inlet unstart is avoided.…”

Section: A Overviewmentioning

confidence: 99%

Periodic forcing of a shock train in Mach 2.0 flow

Hunt

Driscoll

Gamba

2017

55th AIAA Aerospace Sciences Meeting

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High-speed schlieren movies and pressure measurements are collected to analyze the response of a shock train due to downstream forcing. The shock train is generated in a Mach 2.0 ducted flow and controlled by a downstream butterfly valve. Cyclic opening and closing of the valve (at rates up to 10 Hz) leads to oscillations in back pressure measured at the end of the duct. Subsequently, the shock train oscillates between two locations in the duct, traveling at speeds up to 3.5 m/s. Different cases with varied forcing frequency and magnitude of back pressure change are studied. For each case we evaluate the response of the back pressure and shock location by quantifying the magnitude of change, rise time, delay time, and maximum rate of change. Some of the key results include: 1) there is a linear relationship between the magnitude of the shock displacement and the back pressure change that is independent of the forcing parameters; 2) the leading shock in the shock train responds to forcing ≈6 ms after the back pressure starts to change indicating an upstream propagating disturbance; 3) the rise time of the back pressure and leading shock location are approximately the same.

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Experimental Investigation of the Unstart Process of a Generic Hypersonic Inlet

Cited by 103 publications

References 12 publications

Mathematical modeling and characteristic analysis of scramjet buzz

Mathematical modeling and characteristic analysis of scramjet buzz

Mechanism and Prediction for Occurrence of Shock Train Sharp Forward Movement

Periodic forcing of a shock train in Mach 2.0 flow

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