PREDICTION FOR DISCHARGES OF

LABYRINTH-CHANNEL EMITTERS BASED ON COMPUTATIONAL FLUID DYNAMICS

ZHANG Jun  ZHAO Wanhua  CU Qiangyi  TANG Yiping  LU Bingheng

(State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710049 )

Abstract: A physical model for discharges prediction of emitters is reconstructed by reversing the structures of emitter molded parts, and both laminar flow model and turbulence model are adopted to calculate the discharges of labyrinth- channel emitters under the pressure values of 40~150 kPa. Experiments are also performed to test the relationship between emitter discharges and pressure heads. The experimental results verify the feasibility of predicting discharges based on computational fluid dynamics (CFD), and it is also found that turbulence model provides better prediction accuracy than laminar flow model does. In addition, the analyses of the flow field distribution in labyrinth channel show that the transitional Reynolds number is much lower than 2 300 due to the continuous sharp bends. At the Reynolds number 250～300, the flow transition occurs, which leads to the fact that the flow inside this emitter is turbulent under the pressures of 40～150 kPa.

Key words: Emitter Computational fluid dynamics Labyrinth-channel Reynolds stress model

CLC No: TTK124 S277.9

国家高技术研究发展计划(863计划, 2002AA2Z4081, 2005AA2Z4040)和国家自然科学基金(50275119)资助项目. Received 20060524, received in revised form 20061127