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Impulse Generation by an Open Shock Tube

Kasahara, J. and Liang, Z. and Browne, S. T. and Shepherd, J. E. (2008) Impulse Generation by an Open Shock Tube. AIAA Journal, 46 (7). pp. 1593-1603. ISSN 0001-1452. doi:10.2514/1.27467.

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We perform experimental and numerical studies of a shock tube with an open end. The purpose is to investigate the impulse due to the exhaust of gases through the open end of the tube as a model for a partially filled detonation tube as used in pulse detonation engine testing. We study the effects of the pressure ratio (varied from 3 to 9.2) and the volume ratio (expressed as fill fractions) between the driver and driven section. Two different driver gases, helium and nitrogen, and fill fractions between 5 and 100% are studied; the driven section is filled with air. For both driver gases, increasing the pressure ratio leads to larger specific impulses. The specific impulse increases for a decreasing fill fraction for the helium driver, but the impulse is almost independent of the fill fraction for the nitrogen driver. Two-dimensional (axisymmetric) numerical simulations are carried out for both driver gases. The simulation results show reasonable agreement with experimental measurements at high pressure ratios or small fill fractions, but there are substantial discrepancies for the smallest pressure ratios studied. Empirical models for the impulse in the limits of large and small fill fractions are also compared with the data. Reasonable agreement is found for the trends with fill fractions using the Gurney or Sato model at large fill fractions, but only Cooper’s bubble model is able to predict the small fill fraction limit. Computations of acoustic impedance and numerical simulations of unsteady gas dynamics indicate that the interaction of waves with the driver-driven gas interface and the propagation of waves in the driven gas play an essential role in the partial-fill effect.

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Shepherd, J. E.0000-0003-3181-9310
Additional Information:© 2008 by California Institute of Technology, Pasadena, CA. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission. Received 24 August 2006; revision received 1 March 2008; accepted for publication 7 March 2008. We thank R. Deiterding of the DOE ASC Alliance Center for assistance in using the AMROC software and also D. Lieberman, S. Jackson, and F. Pintgen for help with the experimental setup. Z. Liang was partially supported by an NSERC Postgraduate Scholarship from Canada and J. Kasahara’s stay at Caltech was supported by a fellowship from the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan. We also thank Katsumi Tanaka, National Institute of Advanced Science and Technology, Japan, for his advice regarding the simulations and Hans Hornung, Caltech, for creating Figs. 4 and 11.
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Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Ministry of Education, Culture, Sports, Science and Technology (MEXT)UNSPECIFIED
Issue or Number:7
Record Number:CaltechAUTHORS:KASaiaaj08
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:11352
Deposited By: Archive Administrator
Deposited On:07 Aug 2008 04:26
Last Modified:08 Nov 2021 21:57

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