High-Speed Schlieren and Particle Image Velocimetry of the Exhaust Flow of a Pulse Detonation Combustor

Haghdoost, Mohammad Rezay; Edgington-Mitchell, Daniel; Paschereit, Christian Oliver; Oberleithner, Kilian

doi:10.2514/1.j058540

Cited by 11 publications

(13 citation statements)

References 43 publications

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“…Data from both sensors is acquired at a sampling rate of 1 MHz using a National Instruments MXI-Express DAQ system. More details on the PDC facility are provided by Rezay Haghdoost et al (2020b).…”

Section: Facility Descriptionmentioning

confidence: 99%

“…The motivation of this paper is to detail how the non-quiescent medium alters the diffraction of a shock wave exhausting from a pulse-detonation combustor (PDC) (Wolański 2013;Pandey & Debnath 2016;Rezay Haghdoost et al 2021). Rezay Haghdoost et al (2020b) demonstrated that the exhaust of the PDC contained either a detonation wave or a strong shock wave decoupled from the reaction front, depending on the fill fraction. In their valveless PDC, the air continuously flows through the combustor; when a detonation is initiated, the flow ahead of the detonation is not stagnant and the assumption of negligible fluid velocity upstream of the propagating shock wave is no longer valid.…”

Section: Introductionmentioning

confidence: 99%

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Diffraction of shock waves through a non-quiescent medium

et al. 2022

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An investigation of shock diffraction through a non-quiescent background medium is presented using both experimental and numerical techniques. Unlike diffracting shocks in quiescent media, a spatial distortion of the shock front occurs, producing a region of constant shock angle. An example of this process arises in the exhaust from a pulse-detonation combustor. As the background velocity is increased, such as through the inclusion of a converging nozzle at the exhaust, the spatial distortion becomes more apparent. Numerical simulations using a compressible Euler solver demonstrate that the distortion is not due to the geometrical influence of the nozzle, but rather is a function of the magnitude of the background flow velocity. The distortion is studied using a modified geometrical shock dynamics formulation which includes the background flow and is validated against experiments. A simple model is presented to predict the shock distortion angle in the weak-shock limit. Finally, the axial decay behaviour of the shock is investigated and it is shown that the advection of the shock by the background flow delays the arrival of the head and tail of the expansion characteristic at the centreline. This leads to an increase in the rate of decay of the shock Mach number as the background flow velocity is increased.

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Section: Facility Descriptionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Diffraction of shock waves through a non-quiescent medium

et al. 2022

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“…with the measurement duration t meas and the sampling frequency f s 1 MHz. Frequencies with f < f 0 are neglected, where f 0 f eff 1∕2f tube (5) This results in pressure oscillations generated by propagating shock waves subsequent to the firing of the PDC tubes to be neglected while relevant acoustic oscillations remain unchanged. The presented methodology allows for the detailed evaluation of the recorded pressure signals in the annular plenum with respect to the shape and frequency of excited acoustic modes, as well as their respective energy.…”

Section: Signal Processingmentioning

confidence: 99%

“…Hence, minimizing pressure fluctuation downstream of a PDC is a major challenge for realizing its integration into a gas turbine. Two approaches have been proposed to reduce pressure fluctuations at the turbine inlet downstream of a PDC: adjusting the operation parameters, such as firing frequency and firing pattern, and integrating a plenum upstream of the turbine [5,6]. Experiments conducted by Rouser et al [4] revealed a decrease in the amplitude of the observed pressure fluctuations with increasing firing frequency resulting in an increase in turbine efficiency.…”

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Acoustic Modes in a Plenum Downstream of a Multitube Pulse Detonation Combustor

et al. 2021

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“…Moreover, the deflagration to detonation transition would be impossible if the fill fraction was extremely low. Haghdoost [12] conducted an experiment on flow dynamics during one full pulsed detonation cycle via high-speed particle image velocimetry, and the deflagration was observed when fill fraction could not satisfy the distance of deflagration to detonation transition requirement. Bradley [13] verified the deflagration to detonation transition was possible if autoignition of the reactants occurred in the time available and if the projected flame speed approached the Chapman-Jouguet velocity at the same temperature and pressure.…”

Section: Introductionmentioning

confidence: 99%

Research on Optical Diagnostic Method of PDE Working Status Based on Visible and Near-Infrared Radiation Characteristics

Huang

Kang

2021

Energies

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Fill fraction not only has a profound impact on the process of deflagration to detonation in pulsed detonation engine, but also affects the propulsion performance in both flight and ground tests. In this paper, a novel optical diagnostic method based on detonation exhaust radiation in visible and near-infrared region within 300–2600 nm is developed to determine the current working state in the gas–liquid two-phase pulsed detonation cycle. The results show that the radiation characteristic in each stage of detonation cycle is unique and can be a good indicator to infer the fill fraction. This is verified experimentally by comparison with the laser absorption spectroscopy method, which utilizes a DFB laser driven by ramp injection current to scan H2O transition of 1391.67 nm at a frequency of 20 kHz. Due to concentrated radiation intensity, time duration reaching accumulated radiant energy ratio of 50% in detonation status would be smaller than 1.2 ms, and detonation status would be easily distinguished from deflagration with this critical condition. In addition, the variation of important intermediates OH, CH, and C2 radicals during detonation combustion are obtained according to the analysis of detonation spectrum, which can also be proposed as a helpful optical diagnostics method for the combustion condition based on C radical concentration. The study demonstrates the feasibility of optical diagnostics based on radiation in visible and near-infrared regions, which could provide an alternative means to diagnose and improve pulsed detonation engine performance.

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High-Speed Schlieren and Particle Image Velocimetry of the Exhaust Flow of a Pulse Detonation Combustor

Cited by 11 publications

References 43 publications

Diffraction of shock waves through a non-quiescent medium

Diffraction of shock waves through a non-quiescent medium

Acoustic Modes in a Plenum Downstream of a Multitube Pulse Detonation Combustor

Research on Optical Diagnostic Method of PDE Working Status Based on Visible and Near-Infrared Radiation Characteristics

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