Abstract
Paper discusses aerodynamics and potential engineering applications of an unusual and in literature practically unknown fluid flow configuration, with two wall-jets attached to a cylindrical surface so that they collide head-on and by mutual conjunction generate a single jet directed away from the wall. Applications are envisaged in pneumatic sensors, particularly those operating at low Reynolds numbers. Performed experimental investigation, combined with numerical flowfield computations, revealed several interesting aspects. The most interesting among them is the discovery of symmetry-breaking existence of three different stable flow regimes. This opens a possibility for fluidic tristable amplifiers and systems operating with ternary logic.
Highlights
The key problem of fluidics — the technique of handling fluids without action of mechanical components — is how to set up a useful flowfield that responds by a substantial change of their character to a weak control flow input
A typical example of such sensitive flow is the jet used in diverter type fluidic amplifiers
Of high importance to fluidic amplifiers are wall-jets - generated by fluid flow issuing from a nozzle and on one side bounded by a wall
Summary
The key problem of fluidics — the technique of handling fluids without action of mechanical components — is how to set up a useful flowfield that responds by a substantial change of their character to a weak control flow input. There are intriguing flowfield configurations having a certain relation to both colliding jets and wall jets, yet so far at the periphery of interest. They are so sensitive to the ratio of their momenta that it may be difficult to set them up into the balanced state with the stagnation point of collision in the middle distance between two geometrically identical opposed nozzles. The solution is to supply both nozzles from the same fluid source This is easy to arrange in the case of colliding wall-jets curved by Coanda-effect attachment to the same cylindrical surface, as presented in Fig. 1.This flow configuration is set up by placing a cylindrical body between the lips of a very wide nozzle exit, leaving a slit on both sides. The experimental approach was supplemented by numerical flowfield computations where such disturbances by probes are absent
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