Jet Nozzle Case Study

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2. LITERATURE SURVEY 2.1. Experimental Study of a Nozzle using Fluidic Counter-Flow for Thrust Vectoring. Jeffrey D.Flamm, NASA Langley Research Center, Hampton, Virginia Illustrates the benefits of fluidic thrust vectoring concepts to the modern fighter aircraft. Aircraft combat effectiveness is increased with the addition of Thrust vectoring capability to the aircraft’s propulsion system. In close air to air combat, Thrust Vectoring allows the aircraft to operate in the post stall flight regime. This provides a tactical advantage by increasing aircraft agility and maneuverability. A further advantage is gained in long range combat by reducing signature and increasing range. The ability to land and take off from short unimproved runways is…show more content…
This phenomenon known as Coanda effect, is the operating principle of the fluidic thrust vectoring system discussed here. Two secondary jet nozzles are placed above and below the main jet nozzle. Deflections of the secondary jets caused by curved surfaces mounted alongside them trigger a deflection of the main jet. Thus, pitch control can be achieved by controlling the velocity of the secondary jets. Another critical design driver is the shape of the main jet outflow velocity profile. The effectiveness of an FTV system can be significantly impaired by a peaky profile i.e., if the speed of the flow is high in the center but falls away sharply towards the side wall. This can be avoided by careful shaping of the nozzle and thus a second objective can be formulated: the outflow distortion factor must be…show more content…
The nozzle was designed with a recessed cavity to enhance the throat shifting method of fluidic thrust vectoring. The structured grid, computational fluid dynamics code PAB3D was used to guide the design and analyze over 60 configurations. Nozzle design variables included cavity convergence angle, cavity length, fluidic injection angle, upstream minimum height, aft deck angle, and aft deck shape. All simulations were computed with a static freestream Mach number of 0.05, a nozzle pressure ratio of 3.858, and a fluidic injection flow rate equal to 6 percent of the primary flow rate. Results indicate that the recessed cavity enhances the throat shifting method of fluidic thrust vectoring and allows for greater thrust vector angles without compromising thrust

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