Shock Tubes

Igra, O.; Houas, L.

doi:10.1007/978-3-319-23745-9_1

Cited by 5 publications

(6 citation statements)

References 17 publications

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“…This is achieved by passing processed test gas over a scaled model of the space vehicle placed inside the test section of the facility (refer to Figure 1) (Igra, 2015). The specified flow conditions that pass over this model typically last for a few milliseconds, which is a sufficient amount of time to study the flow field surrounding the spacecraft model in these extreme test conditions (RWTH Aechen University, 2007).…”

Section: Impulse Facilitiesmentioning

confidence: 99%

“…There exists a variety of different impulse facilities but the highest performing facilities employ a technique first pioneered by Stalker (1972). In this technique, a sliding piston is utilised to compress a light driver gas in the compression tube which ruptures a diaphragm and expands into the tube with the test gas, thus creating a strong shock wave (Igra, 2015). The test gas is then processed by this shock wave, and then processed by a reflected shock and expanded through a nozzle (in the case of a shock tunnel) or processed by an unsteady expansion into a low pressure acceleration tube (in the case of an expansion tube) (Toniato et al, 2015).…”

Section: Impulse Facilitiesmentioning

confidence: 99%

“…Ruptured Primary Diaphragm When the primary diaphragm bursts, the expanding driver gas behaves like a piston which compresses the test gas and accelerates it towards the test section (Igra, 2015). A shock wave is developed in the process which processes the test gas and this test gas is then processed again by a reflected shock.…”

Section: Unruptured Primary Diaphragmmentioning

confidence: 99%

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Explicit finite element analysis of high speed piston impacts

Yusuf¹

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The University of Queensland operates three large scale free-piston drivers which consists of the T4, X2 and X3 facilities. These facilities are designed for the worst case scenarios based on conservative analytical impact mechanics, in terms of avoiding catastrophic piston impacts. However, these do not accurately predict the mechanical response for complex real geometry in the event of a piston impact.In 2009, there was a high speed impact of a heavy piston that rendered the facility inoperable for two months. Repeated attempts were made to relieve enough stress in the plastically deformed piston to dislodge it from the compression tube. This impact reiterated the potential damage that can be caused by incorrect operation of the free-piston drivers and revealed that there was no structured methodology to estimate the condition of the facility to inform the repair procedure.In this study, the AUTODYN solver was used to investigate three main explicit structural analysis problems including recreating the 2009 T4 high speed piston impact, perfoming a transient stress analysis of the peak pressure loadings acting on X2's lightweight piston using high strain rate material data and analysing the buffer for the X3 facility.The approach to this study involved testing the solver's ability to capture the physical mechanisms involved during a high speed piston impact. An axisymmetric analysis of T4 shot 10509 was later developed where the numerical results were compared to observational comments of the facility made by the technician following the repair job. This approach to using an axisymmetric model was also used to analyse the peak pressure loadings acting on the X2 piston and the results from this were validated against a static structural analysis. An axisymmetric model of the X3 buffer was developed and this was validated against a 3D model. This study has shown that the AUTODYN solver can be used to model high speed piston impacts with relative confidence. Furthermore, there was enough evidence to show that the numerical recreation of T4 shot 10509 did agree with the technician's observations following T4 shot 10509. This allowed for the response of the facility at higher impact speeds and with varying material properties to be investigated. The transient analysis conducted for the X2 lightweight piston agreed closely with the static structural analysis conducted prior. Since the X3 lightweight piston was made out of similar materials to the X2 piston, this validated the material data used for the X3 piston. It was also discovered that the nylon studs in the X3 facility would not likely fracture from an impact speed of 30 m/s by the X3 lightweight piston. This quantification of safe impact speeds for the X3 buffer was deemed important following the development of new driver operating conditons for the X3 facility.ii Acknowledgements Foremost, I would like to thank my supervisor Dr Gildfind for his continued support throughout the year, and faith in my ability to overcome all obstacles that got in my way....

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Section: Impulse Facilitiesmentioning

confidence: 99%

Section: Impulse Facilitiesmentioning

confidence: 99%

Section: Unruptured Primary Diaphragmmentioning

confidence: 99%

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Explicit finite element analysis of high speed piston impacts

Yusuf¹

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“…For Mach numbers less than 8, single or multiple layers of Mylar are used, and above Mach 8, a pre-scored steel diaphragm is used. When a stoichiometric combination of hydrogen and oxygen are used (with 77.5% other gases to dilute), peak pressures up to 400bar can be achieved in the combustion chamber [25].…”

Section: Brief Review Of Currently Operating Shock Tubesmentioning

confidence: 99%

“…Both of these tubes utilise a primary diaphragm to hold the driver gas pressure before initiation of the test [25].…”

Section: Brief Review Of Currently Operating Shock Tubesmentioning

confidence: 99%