From collisionless to continuum: Dilute jet and impingement flows

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Conference Proceeding

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Department of Mechanical Engineering-Engineering Mechanics


Rarefication effects on jet impingement loads are studied by comparing recent new formulas at the collisionless flow limit and numerical simulations. The jet exit width is finite, and can be either planar or round. In the simulations, jets have different degrees of rarefication, with a Knudsen (Kn) number ranging from 0 to infinity; i.e., the jet flows can be continuum, collisional, or collisionless. The comparison results indicate that (1) the new surface load formulas are accurate at the collisionless flow limit; (2) in general, the formulas offer upper limits for the highest load; (3) however, it is improper to assert that local loads always decrease. The new formulas can help fast estimations on impingement loads. This may be helpful for applications in space engineering by significantly reducing the amount of simulations and experiment cost. Those expressions explicitly include non-dimensional parameters, and their contribution and influence on the loads can be studied with a swift parameter study.

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© 2019 AIP. Publisher’s version of record:

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AIP Conference Proceedings