Superquadratic Fluidic Restrictors And Their Applications
Free (open access)
507 - 519
In a little-known type of flow restrictors the resistance to flow is due to centrifugal force acting on the fluid rotating in a shallow cylindrical chamber into which it enters tangentially. The advantage over other restrictor types is high achievable pressure drop in relation to quite large flowpath cross-sections. The super-quadraticity – which is steeper than the quadratic rise of the pressure drop with increasing flow rate – is an interesting and yet almost unknown property of these restrictors. This paper presents examples of the effect and its applications. Keywords: flow restrictors, vortex devices, rotating flow, fluidics. 1 Introduction In view of the general requirements of efficiency it may seem contradictory to common sense to develop and use hydraulic and pneumatic devices having no other purpose than to dissipate the energy of fluid that passes through them. Yet such devices, hydraulic or pneumatic restrictors (general term: fluidic restrictors) are not only useful but actually very important. Their typical application is limiting the discharge of fluid accumulated in a pressure vessel after its sudden opening. Another use is suppression of fluid flow pulsation. Related case is damping mechanical motion converted by a piston transducer into the fluid flow. Yet another use is \“gagging” of the inlets into several parallel flowpaths to secure uniform flow distribution into them. There are also numerous applications in sensors: a well-known example is the evaluation of flow rate by measuring the pressure drop across a restrictor. Presented in Fig. 1 are three different operating principles used for these tasks, named according to the ideal value of the exponent n of their characteristic – the dependence of pressure drop P on volume flow rate P V n (1)
flow restrictors, vortex devices, rotating flow, fluidics.