Experimental study of shock tunnel flow with a stationary throat plug

Lee, Jong-Kook; Park, C.; Kwon, Ohjoon

doi:10.1007/s00193-012-0370-2

Cited by 7 publications

(10 citation statements)

References 13 publications

(12 reference statements)

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“…By following the previous experiments conducted by the authors of the present work [7], additional experiments were carried out to study the effect of the throat plug configuration. All throat plugs had an areal blockage of 19.4%, and the tests were made in the same nozzle named NOZ2 in [7].…”

Section: Throat Plug Experimentsmentioning

confidence: 99%

“…1. With this information, it is approximately inferred that the throat plug with a 19.4% blockage in [7] is appropriate for the freestream Mach numbers above 5.…”

Section: Introductionmentioning

confidence: 96%

“…Recently, the authors of the present work carried out a two-dimensional numerical study on a stationary throat plug [6]. An axisymmetric experimental study [7] was also conducted to investigate how the flow is affected by the presence of the throat plug in a shock tunnel located at Korea Advanced Institute of Science and Technology (KAIST). The results showed that a throat plug with an areal blockage of 6.2% has negligible effects on the shock-tunnel flow.…”

Section: Introductionmentioning

confidence: 99%

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Experimental and Numerical Study of Stationary Throat Plug in Shock Tunnel

Lee

Park

Kwon

2015

Journal of Thermophysics and Heat Transfer

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A throat plug is a device in a shock tunnel to prevent fragments, produced by the bursting of the primary diaphragm, from entering the nozzle and damaging the model. In the present study, a series of experimental and numerical studies has been carried out to investigate the flows around stationary throat plugs in a shock tunnel. For this purpose, conical, circular, and double circular stationary throat plugs that have a 19.4% areal blockage were used as the test models. The primary shock velocity was set at 1.19 km∕s, and the shock generated a tailored condition when helium and air were used as the driver and driven gases at room temperature. In the experiment, the nozzle reservoir pressure and the pitot pressure at the nozzle exit were measured to examine the influence of the throat plug. It was found that, from both the experiment and the calculation, all types of the plugs generate a pressure bump in the nozzle reservoir during the transient period of interaction between the reflected shock and the plugs. After the transient period, the difference between the plug-distorted and -undistorted nozzle flows is small and can practically be neglected. When the driven tube diameter is increased in the region in which the throat plug is located, the pressure bump is almost eliminated. However, according to the calculation, the increased diameter causes an augmentation in the temporal enthalpy and the entropy at the nozzle exit. The spatial distribution of the entropy in the radial direction shows little change. The configuration of the plug has little influence on the shock-tunnel flow when the plug is placed in the region in which the plug does not distort the nozzle flow.

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Section: Throat Plug Experimentsmentioning

confidence: 99%

“…1. With this information, it is approximately inferred that the throat plug with a 19.4% blockage in [7] is appropriate for the freestream Mach numbers above 5.…”

Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

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Experimental and Numerical Study of Stationary Throat Plug in Shock Tunnel

Lee

Park

Kwon

2015

Journal of Thermophysics and Heat Transfer

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“…During the steady-flow test time, abrupt peaks in the test section flow pressure occurred more often with the moving plug system than the stationary plug system. Apart from these peaks, the differences in moving and stationary plug readings were negligible [33]. It was determined that the test flow for both cases was acceptably close to the no plug flow case [31].…”

Section: Throat Plugmentioning

confidence: 89%

“…Bird's idea lead to further investigation of the throat plug mechanism as a means to stop fragmentation damage in shock tubes, this was conducted by J. Lee et al [31][32][33][34] from 2012 to 2015.…”

Section: Throat Plugmentioning

confidence: 99%

Feasibility analysis of a rapid opening valve as a thin film diaphragm replacement for expansion tubes

Wilson¹

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AcknowledgmentsI would first like to thank my supervisor, Doctor David Gildfind, whose willingness to consistently make time to meet and discuss progress and problems has been greatly appreciated. Your passion and professionalism are traits I hope I can emulate throughout my engineering career.I also want to thank my father, Lewis, for applying his extensive knowledge in entomology to issues such as valve sealing and piston decelerating methods; my mother and brother for their unwavering faith in my ability; and my sister for showing me that unabashed passion is the only way to approach your chosen field.Finally, I want to thank my room-mates and friends who listened and discussed my project throughout the year and distracted me when I needed a break. PAGE: III AbstractThe objective of this thesis was to assess the feasibility of replacing the thin film diaphragm on the University of Queensland's X2 expansion tube facility with a valve system. The aim of developing this system is to avoid issues associated with the use of the thin film diaphragm, while still producing acceptable test flows. To ensure the test flows are still acceptable, the valve must open in less than 0.5ms, as defined by Burgess [1]. The critical issue introduced by the utilization of a thin film diaphragm is that, upon impact by the shock, the thin film diaphragm is broken into fragments. These fragments can be accelerated into the test section by the flow where they may impact and damage instrumentation. There have been multiple attempts to avoid the diaphragm fragmentation issue. These attempts were compiled and assessed and it was concluded that none satisfactorily avoided the issues introduced by the thin film diaphragm without potentially significantly deviating the expansion tube test flow. To successfully replace the thin film diaphragm, a system which completely clears the expansion tube bore, rapidly, and with minimal disturbance to the surrounding gas, while maintaining a low leakage seal is required. An investigation showed that a gate valve best fulfilled this criterion. A gate valve consists of a flat plate of metal with a hole in it, termed the 'knife'. To open the valve, the knife is moved such that the hole aligns with the expansion tube bore. The gate valve should be accelerated and decelerated pneumatically, while being sealed using a PTFE encapsulated X-ring pressed against the face of the knife. To achieve the required opening time without knife failure due to excessive stresses, the knife length before the hole should be increased to allow the knife to be accelerated at a lower rate for a longer period of time before the hole begins to clear the expansion tube bore. Similarly, the length of the hole in the knife should be increased so the knife can be decelerated over a longer distance. Analytical equations to approximate knife, connecting rod and piston failure were developed and shown to be conservative using Finite Element Analysis. These equations were then utilised in an iterative, parametrised Python code which both...

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