Experimental Identification of the Detachment Point on the ACHEON Thrust-Vectoring Nozzle 2015-01-2464

Thrust vectoring is an interesting propulsion solution in aeronautic applications due to its fast response, improving aircraft's performance for take-off, landing and flight, and enabling Short/Vertical Take-Off and Landing (S/VTOL). In this context, an attempt to design a radically new concept of thrust vectoring nozzle is in current development. This novel nozzle, called ACHEON, bases the jet deviation control on the interaction of two primary jets of different velocities, where the one with higher velocity entrains the one with lower velocity. Two cylindrical walls are positioned after the two air jets mixing. If the inlet conditions are not symmetric, the Coanda effect on the walls forces the resulting air jet to divert from the symmetry axis.

This paper shows the experimental pressure distribution along the Coanda wall for different inlet. Besides the generation of experimental data to be utilized for future CFD simulations validation, the obtained results provides important insights on the nozzle controllability. A first significant conclusion is that, for a certain Reynolds number, the air jet detaches at 3 discrete positions instead of offering a continuous range of positions: symmetric jet, diverted to one wall at one position, and diverted to the opposite wall at the analogous position. This position depends on the Reynolds number. A second conclusion is that for scenarios when only one primary jet is active, the air jet is attached to the opposite wall.