Use of acceleration and optical waypoint measurements to estimate piston trajectory in an impulse facility

Gildfind, David; Hines, Thomas; Jacobs, P. A.; Stennett, Samuel; Dimitrijevic, I.

doi:10.1007/s00193-018-0877-2

Cited by 3 publications

(4 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Following the successful shortening of the buffer extension, eight half-pressure X3R experiments were completed (shots x3s710 to x3s718) utilising a piston accelerometer package [111]. This allowed the changes to driver supply time, nozzle supply time, useful test time and the piston dynamics, induced by iterative increases to reservoir pressure, to be quantified.…”

Section: Driver Resultsmentioning

confidence: 99%

“…The piston accelerometer package [111] was mounted to the 280 kg piston during experiments x3s710 to x3s718, to evaluate the piston trajectory. This allowed further condition refinement through observation of the piston response to alterations to the reservoir pressure.…”

Section: Piston Dynamics Resultsmentioning

confidence: 99%

“…This experimental campaign sought to further optimise the condition by evaluating the effects of reservoir pressure iteration on the piston dynamics and facility performance. Use of a piston accelerometer package [111] allowed the experimental piston trajectory to be investigated, confirming that piston reversal occurred due to the reflected shock arrival. This reversal ultimately resulted in a high velocity rebound-impact even though a soft-landing trajectory was originally achieved.…”

Section: Chapter 8 Conclusionmentioning

confidence: 90%

“…A piston accelerometer package, developed by Gildfind et al [111] specifically for operation 540mm Figure 7.3: X3R buffer extension prior to first experiment.…”

Section: Methodsmentioning

confidence: 99%

See 3 more Smart Citations

Development of an extended test time operating mode for a large reflected shock tunnel facility

Stennett¹

View full text Add to dashboard Cite

X3R is a new free-piston driven reflected shock tunnel (RST) facility, derived from the X3 free-piston super-orbital expansion tube at the University of Queensland (UQ). X3R is the first dual-mode impulse facility in Australia, and is also the first dual-mode free-piston impulse facility originating as an expansion tube. Conversion and operation of the facility in a reflected shock tunnel mode was originally envisioned as a means to increase the scale and duration of Australia's hypersonic testing capability, which was previously limited in both aspects in comparison to other international impulse facilities. This thesis was completed to coincide with the physical X3R facility hardware design and development, to produce an operating condition capable of generating and maintaining a Mach 7, 50 kPa dynamic pressure test flow for 10 ms. It was initially postulated that this could be efficiently achieved using the pre-existing X3 facility hardware, new components designed specifically for reflected shock tunnel mode, and a new operating condition. Due to its parallel operation as an expansion tube, X3R featured a driver tube length that was 60% that of the shock tube in RST mode. These geometric proportions are unique compared to other facilities of this kind throughout the world, which typically feature driver tubes that are at least twice the shock tube length. Operation of a reflected shock tunnel with such a relatively short driver tube makes it extremely challenging to efficiently utilise the 'full' slug of test gas. The primary challenge was generating a pulse of gas from the driver with sufficient duration to fully shock the test gas and sustain critical flow processes until 10 ms of test flow at the target conditions had been generated. The solution to this challenge was careful configuration of the free-piston driver and quite unconventional driver operation. Theoretical analysis showed that a very low compression ratio was required to maximise the volume of the driver gas. Given the low compressive heating, this resulted in a much higher helium fraction that would be normally required to produce a free-piston driven 1400 m/s shock through air. The low compression ratio then required significant piston energy to compress the gas, leading to extended periods of high facility and piston loading. Sustaining a relatively steady driver gas pressure to drive the downstream flow processes required piston speed to be maintained immediately after diaphragm rupture. This driver gas 'hold time' was shown to depend on piston mass; the higher the driver gas pressure, the heavier the piston needed to be to sustain a given test time. Once this fundamental dependency had been identified, it was determined that if piston mass and test flow dynamic pressure were fixed, there was a maximum test time that could be achieved. Conversely, if piston mass and test time were specified, there was a fundamental limit to the achievable test flow dynamic pressure. For the initial configuration analysed in this thesis, it was found that, ...

show abstract

Section: Driver Resultsmentioning

confidence: 99%

Section: Piston Dynamics Resultsmentioning

confidence: 99%

Section: Chapter 8 Conclusionmentioning

confidence: 90%

“…A piston accelerometer package, developed by Gildfind et al [111] specifically for operation 540mm Figure 7.3: X3R buffer extension prior to first experiment.…”

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Development of an extended test time operating mode for a large reflected shock tunnel facility

Stennett¹

View full text Add to dashboard Cite

show abstract

Microwave radar diagnostics of piston motion in a free-piston-driven expansion tube

Kurosaka,

Shimamura

2024

Shock Waves

View full text Add to dashboard Cite

Application of microwave radar is a useful approach to gauge piston motion in a free-piston driver. One difficulty associated with conventional microwave technique is its spatial resolution during rapid velocity shifts at diaphragm rupture timings. This study, while departing from the standard practice of analyzing standing wave peaks, introduces an alternative by examining the phase shift of the microwave in-phase and quadrature signals. A compact free-piston-driven expansion tube, MX6.0, is used as the test bed for this technique. A microwave frequency of 4.2 GHz is used to take measurements in a compression tube with a diameter of 50 mm and a length of 2.0 m, tracking the motion of the piston. After arranging the microwave radar systems, the piston velocity and displacement trajectory are measured. Compared to the lower-resolution measurements using conventional microwave wavelength intervals, the use of microwave phase allowed for an exceptionally high spatial resolution in analyzing the piston motion.

show abstract

Large-scale free-piston-driven multi-mode shock expansion tunnel

Stennett,

Gildfind,

Andrianatos

et al. 2024

Exp Fluids

View full text Add to dashboard Cite

X3/R is a new large-scale free-piston-driven dual-mode shock expansion tube, developed and operated collaboratively by the University of Queensland (UQ) and Australia’s Defence Science and Technology Group (DSTG). The facility can be converted between a long-duration reflected shock tunnel (RST), a super-orbital expansion tube (X-mode), and a non-reflected shock tube (NRST). In RST mode, the facility is currently capable of producing 600 mm diameter Mach 7 test flows at 25–50 kPa dynamic pressure for more than 10 ms. In expansion tube mode, the facility can reach enthalpies up to 80 MJ/kg for test times on the order of 500–1000 $${\mu }$$ μ s. This paper presents the new facility, summarizes its current operational capabilities, and discusses key the technical challenges overcome during its development.

show abstract

Use of acceleration and optical waypoint measurements to estimate piston trajectory in an impulse facility

Cited by 3 publications

References 15 publications

Development of an extended test time operating mode for a large reflected shock tunnel facility

Development of an extended test time operating mode for a large reflected shock tunnel facility

Microwave radar diagnostics of piston motion in a free-piston-driven expansion tube

Large-scale free-piston-driven multi-mode shock expansion tunnel

Contact Info

Product

Resources

About