Characterization & Control of Impinging Jets at Realistic Flow Conditions

Due to the conditions created by the takeoff and landing of various fixed wing and rotor aircraft, the operational environment on an aircraft carrier flight deck is very harsh, both for the personnel and the structural components of the deck itself. For example, the high temperature, high velocity jet exhaust from the F / A-18E/F during takeoff and landing produces very high noise levels that may compromise the performance and safety of the flight crew personnel operating in proximity to the aircraft. These high noise levels also propagate through the flight deck, thus making the environment hostile even for personnel below deck. Furthermore, when these high-temperature jets impinge upon the jet blast deflector they generate high thermal and acoustic loads, which result in increased maintenance and operational costs for this structural component. The problems associated with jet impingement will be exacerbated with the introduction of the F-35B, which is a vertical takeoff and landing (VTOL) aircraft. The near­vertical impingement of the lift jets results in a number of adverse ground effects, including: ground/surface erosion of the landing surface due to the high temperature, highly unsteady impinging jets; significantly higher noise levels (as compared to conventional take-off aircraft); lift loss due to enhanced ambient flow entrainment associated with the lifting jets; and hot gas ingestion, where the outwash from the impinging jets is drawn into the engine inlet(s). These properties pose an additional risk to the crew operating near such aircraft, and also affect the integrity of the carrier flight deck. In order to understand and address the challenges posed by this operational environment, an interdisciplinary, integrated approach is needed involving key technologies in, but not limited to, the areas of aeroacoustics, materials, and structural vibrations and acoustics. Furthermore, it is critical that this problem is studied under the realistic conditions of the carrier flight deck operational environment.