The purpose of this paper is to design and develop an advanced co-flow fluidic nozzle, based on the Coanda effect concept, for multi-directional thrust vectoring of small jet engines. Recent progress on finding an optimal geometry with a fixed momentum ratio to achieve maximum thrust deflection angle is discussed here. The efficiency of the system is found to be a weakly nonlinear function of the secondary to primary flow momentum as well as three geometric parameters. A useful empirical formulation is derived for thrust vectoring angle, based on a series of tests carried out on different nozzles. An accurate computational fluid dynamics model is also developed and evaluated against the experimental data. Moreover, quasi-Newton optimisation algorithm is employed to find an optimal geometry with a constant relative jet momentum and a constant secondary slot size. In this technique, the optimal wall geometric parameters are calculated in the direction of the steepest gradient with the help of the numerical simulation model in every iteration step. Additionally, an optimised fluidic nozzle is constructed to experimentally verify the numerical results and the empirical equation.

This paper presents the application of a relatively newtechnique of fluidic thrust-vectoring (FTV), namedCo-flow, for a small gas-turbines. The performanceis obtained via experiment and computational fluiddynamics (CFD). The effects of a few selectedparameters including the engine throttle setting,the secondary air mass-flow rate and the secondaryslot height upon thrust-vectoring performance areprovided. Thrust vectoring performance ischaracterised by the ability of the system todeflect the engine thrust with respect to thedelivered secondary air mass-flow rate. Theexperimental study was conducted under staticconditions in an outdoor environment at CranfieldUniversity workshop that was especially designed forthis purpose. As part of this investigation, thesystem was modelled by CFD techniques, usingPointwise’s Gridgen software and thethree-dimensional flow solver, Fluent. Also,Cranfield’s gas-turbine performance code(TurboMatch) was utilised to estimate boundaryconditions for the CFD analysis with respect to theintegrated nozzle. The presented technique iseasy-to-use approach and offers better result forthrust-vectoring problems than previously publishedworks. Experimental results do show the overallviability of the blowing slot mechanism as a meansof vectoring the engine thrust, with the currentconfiguration. Computational predictions are shownto be consistent with the experimental observationsand make the CFD model a reliable tool forpredicting Co-flow fluidic thrust-vectoringperformance of similar systems.