Impulse Generated by a Shock Tube in a Vacuum

Abstract

Detonation tube specific impulse increases with decreasing ambient pressure for fullyfilled conditions in a sub-atmospheric environment. In the present study, we use an openend shock tube to simulate a detonation tube and investigate the dependence of the specific impulse on the propellant fraction, i.e., partial filling, in vacuum operation. The impulse is experimentally determined by hanging the shock tube in a ballistic pendulum arrangement inside a vacuum chamber. The shock tube driver section has a fixed length of 0.1 m and is filled to 1 MPa with various gases including helium, hydrogen, nitrogen, argon, and sulfur hexafluoride. The pressure inside the vacuum chamber is 5 Pa. The shock tube had constant area and different lengths (0-1.2 m) of the open-end driven sections (extension tubes) are used to vary the fraction of gas filling the shock tube (fill fraction) between 7.8% and 100%. The specific impulse is a weak function of extension tube length but varies * = specific impulse scaling parameter I sp (l) = specific impulse of a shock tube with an extension tube of length l L = non-dimensional length

Flow design and simulation of a gas compression system for hydrogen fusion energy production

“…Such a method can also be attractive for other applications requiring rapid compression such as high speed detonators and hammers. The release of high pressure gas into nearly vacuum conditions has already attracted the attention of the space engineering sector for propulsion purposes (Takashima et al 2006). Flow computations based on characteristics arguments and computational fluid dynamics were pursued, and where interestingly quasi-1D flow assumptions were commonly used due to the low computational cost (Takashima et al 2006, Kopasakis et al 2012.…”

“…The release of high pressure gas into nearly vacuum conditions has already attracted the attention of the space engineering sector for propulsion purposes (Takashima et al 2006). Flow computations based on characteristics arguments and computational fluid dynamics were pursued, and where interestingly quasi-1D flow assumptions were commonly used due to the low computational cost (Takashima et al 2006, Kopasakis et al 2012. However, the system proposed in this study differs significantly from the space propulsion systems by having the high pressure gas expanding into a closed enclosure and not free space.…”

Analysis on Thermal Efficiency of Non-Compressor Type Pulse Detonation Turbine Engines

“…Engines obtaining impulsive force by detonation waves include the air-breathing PDEs [6][7][8][9][10][11][12][13][14][15][16] and the Pulse Detonation Rocket Engines (PDREs). [17][18][19][20] These engines are being studied as potential new aerospace engines. 21) In the type called Pulse Detonation Turbine Engines (PDTEs), the high-pressure burned gas generated in the PDE is exhausted into the turbine to obtain shaft power.…”