Preliminary Analysis and Design Enhancements of a Dual-Throat FTV Nozzle Concept

Fluidic thrust vectoring (FTV) can potentially provide the same advantages in aircraft control as traditional thrust vectoring which uses vanes and gimbals, but with reduced weight and radar signature. This paper provides a brief description of the various FTV techniques and a closer look at a novel dual-throat design. Previous works regarding this design do not offer detailed analytical methods to describe the flow within the nozzle. This work examines the validity of using oblique shock theory to obtain a preliminary prediction of the flow behavior. CFD analysis and experiments using hydraulic analogy are performed to verify the analytical solutions. The analysis led to an improved design for the wall contours of the dual-throat nozzle, which is also examined using CFD and hydraulic analogy. CFD results for the proposed design produce a thrust vectoring angle of 24.5 ° with a mass flow rate of 5.47 kg/s. The previously published design produces a thrust vectoring angle of only 13.5 ° with a larger mass flow rate of 6.01 kg/s. The experimental results obtained via hydraulic analogy on a free surface water table are not accurately calibrated enough to quantitatively verify the analytical and computational results, but they do visually demonstrate the major features of the compressible flow phenomena occurring within the nozzle and exhaust. Nomenclature C = Speed of propagation of long gravity waves F = Froude number g = Acceleration due to gravity h = Height of shallow downstream fluid flow ho = Height of upstream fluid reservoir M = Mach number Mn = Mach number normal to oblique shock