Research on transitional flow characteristics of labyrinthchannel emitter

A physical model for flow characteristics analysis of labyrinth-channel emitter is reconstructed by Reverse Engineering from an injection molded part, and both laminar flow and turbulence models are adopted to simulate the flow state under the condition of low Reynolds numbers. According to the distribution of separation and reattachment points, the onset of transition from laminar to turbulent flow in labyrinth channels occurs at a range of Re=250-300. Furthermore, a visualization system of the flow field inside the labyrinth channels is also established and two kinds of tracers are used in the experiments. The experiment of tracing particles verifies the calculated flow field distribution, and another experiment using dyeing liquor showed the critical Reynolds number characterizing the transition, which is reasonably consistent with numerical simulation results. The critical Reynolds number obtained shows the fact that the flow inside this emitter is turbulent under the pressures of 40~150 kPa.