Vortex Flow Control - Passive Stormwater Regulators

About

What is a Vortex Flow Control A vortex flow control device is commonly positioned downstream of an attenuation tank to limit the outgoing flow. The vortex flow regulator initiates a passive vortex in the body of the vortex device. This leads to a notable reduction in discharge rates compared to an equivalent diameter orifice i.e a vortex with the same inlet diameter as an orifice would pass a reduced discharge. Alternatively, the same discharge rate could be passed with a bigger inlet using a vortex device. Benefits of Vortex Flow Control The benefit of a bigger inlet is reduced blockage risk. Another benefit of using a vortex device is presented in the Head-discharge (Q-h) relationship. Vortex development consists of a number of phases. Initially, there is open channel flow until the outlet opening reaches top level, this is briefly followed by orifice control; from this point there is a turbulent transition mode where a vortex initiates; followed finally with fully established vortex flow. The unique nature of this curve means that the average flow of a vortex device is higher in the range of head being considered than an orifice. The upstream storage can therefore be lower using a vortex device. Vortex devices can be attached to a headwall on the outlet of the SuDS basin or more typically they are installed inside a chamber downstream of an attenuation tank/crate system. In order to quote for a vortex device we require: allowable discharge rate head (mm) outlet pipework diameter. The video below shows the principle of vortex flow generation and the resulting reduction in flow when compared to a simple orifice with the same diameter inlet .