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Review

Some Key Issues in Hypersonic Propulsion

1
Mechanical Engineering Department, University of Connecticut, Storrs, CT 06268, USA
2
School of Aerospace Engineering, University of Rome La Sapienza, 00138 Rome, Italy
*
Authors to whom correspondence should be addressed.
Academic Editors: Attilio Converti and Luis Hernández-Callejo
Energies 2021, 14(12), 3690; https://doi.org/10.3390/en14123690
Received: 7 May 2021 / Revised: 1 June 2021 / Accepted: 10 June 2021 / Published: 21 June 2021
(This article belongs to the Special Issue Combustion and Propulsion Systems)
This paper summarizes and discusses some critical aspects of flying hypersonically. The first is the L/D (lift over drag) ratio determining thrust and that in turn depends on the slenderness Küchemann’s τ parameter. This second parameter is found to depend on the relative importance of wave versus friction drag. Ultimately, all engineering drag is argued to depend on vorticity formed at the expense of the vehicle kinetic energy, thus requiring work by thrust. Different mixing strategies are discussed and shown to depend also on mechanisms forming vorticity when the regime is compressible. Supersonic combustion is briefly analyzed and found, at sufficiently high combustor Mach, to take place locally at constant volume, unlike conventional Brayton cycles. View Full-Text
Keywords: scramjet engine; hypersonic propulsion scramjet engine; hypersonic propulsion
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MDPI and ACS Style

Bruno, C.; Ingenito, A. Some Key Issues in Hypersonic Propulsion. Energies 2021, 14, 3690. https://doi.org/10.3390/en14123690

AMA Style

Bruno C, Ingenito A. Some Key Issues in Hypersonic Propulsion. Energies. 2021; 14(12):3690. https://doi.org/10.3390/en14123690

Chicago/Turabian Style

Bruno, Claudio, and Antonella Ingenito. 2021. "Some Key Issues in Hypersonic Propulsion" Energies 14, no. 12: 3690. https://doi.org/10.3390/en14123690

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