Experimental research on a newly developed detonation flame arrester
In this research, a flame arrester consists of radial slit structure is developed. In order to determine the characteristic of the newly developed flame arrester, pressure response and detonation wave velocity are measured using two radial slit structures with different inside diameter. At first, the flow characteristics for the slit structures are investigated theoretically and experimentally. Then, the slit structures are applied to the flame arrester. Detonation experiments are performed for mixture gas of air and hydrogen. It reveals that the radial slit structure with the suitable inside diameter is effective for the flame arrester.
A Study on Behavior of Detonation Wave Passing through Narrow Grooves
A detonation wave produced in a combustible gaseous mixture might cause serious damages by interacting with an artificial structure or human bodies because of an extremely high-pressure and high-temperature behind this wave. Therefore, the detonation wave produced in the gaseous mixture and propagated into a circumstance by accident should be attenuated or quenched within a short distance from its origin. Experiments were conducted in order to investigate behaviors of the detonation wave passing through narrow grooves, since the detonation wave was accompained with a cellular structure and no detonation wave could be propagated. In this study, the detonation wave produced in a gaseous mixture of hydrogen and oxygen was propagated through a grooved block and behaviors of the detonation wave were experimentally investigated by using techniques of pressure measurement and soot track record. As a result, the behavior of detonation wave propagating through the grooved block was classified into two categories, i. e. (i) the detonation wave was quenched, (ii) the detonation wave was once quenched behind the block but re-initiated again by focusing mechanisms of a reflected shock wave on a central axis.
Effects of reservoir volume on performance of pulse tube cooler.
A pulse tube cooler has the advantages of long-life and low-vibration over conventional cryocoolers such as G-M and Stirling coolers because of the absence of moving parts at low temperature. On the other hand, the combination of a reservoir and orifice is indispensable to optimize the performance of pulse tube coolers. In order to make the pulse tube cooler compact for practical applications, the volume of reservoir should be minimized. This paper analyzes the effects of the reservoir volume on the thermodynamic performance of various components in a simple orifice and a double-inlet pulse tube cooler by combining a linearized model with a thermodynamic analysis. Expressions of entropy production for those components are presented. The results show that the reservoir volume has a significant influence on the entropy production in the various components when the reservoir to pulse tube volume ratio is smaller than about 5. The ratio is important to determine the minimum reservoir volume for a pulse tube cooler. Optimum settings for a double-inlet pulse tube cooler are also discussed.