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| Design and analysis of the optimal length for compression tube in the high enthalpy expansion tube |
| Received:September 02, 2015 Revised:November 29, 2015 |
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| DOI：10.7511/jslx201606018 |
| KeyWord:high enthalpy expansion tube piston motion compression tube constant-pressure time bridge curve |
| Author | Institution |
| 李海燕 |
中国空气动力研究与发展中心超高速所, 绵阳 |
| 吕治国 |
中国空气动力研究与发展中心超高速所, 绵阳 |
| 罗万清 |
中国空气动力研究与发展中心超高速所, 绵阳 |
| 常雨 |
中国空气动力研究与发展中心超高速所, 绵阳 |
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| Abstract: |
| The high enthalpy expansion tube facility being constructed in China Aerodynamics Research and Development Center will be driven by a free piston compression tube.The length of the compression tube needs to be optimized in order to make the effective test time as long as possible.The influences of experimental parameters and various driver gases on the constant-pressure time of compression tube were analyzed by numerically solving a set of piston motion model differential equations under the conditions of a single and multi-species driver gases.The numerical solution combined with the theory of bridge curve is used to construct a curve surface composed of local maximum values of constant-pressure time in parameter space.The aforementioned curve surfaces from the cases including four kinds of driver gas (100%H2,85%H2+15%N2,100%He,85%He+15%Ar) and three set of volumetric compression ratios (λ=60,100,140) showed that the altitude of bridge curve for constant-pressure time increases with the ratio of effective length (namely,the initial distance from front face of the piston to the diaphragm located at the terminal of compression tube) of a compression tube to its internal diameter L/D.The optimal length of compression tube was obtained which satisfies the longest constant-pressure time requirement. |
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