Aerodynamic Study of a Venting Device for Air Intake of a Ramjet Engine Lukas Noll, Christoph Bauer Bayern-Chemie GmbH PB Box 1131, 84544 Aschau am Inn, Germany e-mail: lukas.noll@mbda-systems.de, web page: https://bayern-chemie.com/de/ ABSTRACT This paper presents the results and outlook of a concept study conducted by Bayern Chemie GmbH for a venting system for a ramjet air intakes. Unlike all rocket systems with a ramjet phase currently in service, this concept closes the air intake during the boost phase not at the inlet ramp, but in the subsonic diffuser before the ramjet combustion chamber. In addition to simplifying the mechanical complexity of the closure system, this also has the potential of reducing the additional lift caused by a closed inlet. This additional lift affects both the flight mechanics of the missile and the stress it is subjected to due to additional moment loads [1,2]. Initial CFD simulations using (U)RANS of the air intake with venting system showed that noticeable pressure fluctuations can occur in the subsonic diffuser. These vary greatly depending on the configuration of the venting system and the design of the subsonic diffuser. Since these superimposed pressure fluctuations within the air intake during the boost phase place a significant additional loads on the inlet system, a wind tunnel campaign was carried out in the Trisonic Test Section of the DLR in Cologne to validate the CFD simulations. The wind tunnel test campaign confirmed the initial findings from the CFD simulations and showed which configuration of the ventilation system (number, size, and positioning of the gaps) has an influence on the frequency and intensity of the pressure fluctuations. To comprehensively understand the influence of different design parameters on the pressure fluctuations and to mitigate their effect, detailed sensitivity studies using high-fidelity CFD simulations are planned for future. REFERENCES [1] Goldsmith, E., Seddon, M., Intake Aerodynamics, 2nd Edition, Blackwell Science Ltd, 1999. [2] Fleemann, E., Missile Design and System Engineering, 1st Edition, Transatlantic Publishers, 2012.