Comprehensive evaluation indicator of simulation accuracy for two-ways mixed flow emitter
GUO Lin1,2, BAI Dan1*, WANG Xinduan1, WANG Cheng1, ZHOU Wen3, CHENG Peng3
1. Institute of Water Resources and Hydroelectric Engineering, Xi′an University of Technology, Xi′an, Shaanxi 710048, China; 2. Xi′an Chanba Ecological District, Xi′an, Shaanxi 710024, China; 3. School of Water Conservancy, North China University of Water Resources and Electric Power, Zhengzhou, Henan 450011, China
Abstract：In order to evaluate the calculation accuracy and applicability of the numerical simulation method for two-ways mixed flow emitter, 3 kinds of emitter prototypes were designed. Based on the testing of flow rate and fluid velocity by experiment and Particle Image Velocimetry(PIV)technology, the values of flow rate and fluid velocity were obtained under different pressures. The macroscopic flow rate evaluation indicator and microscopic fluid velocity evaluation indicator were proposed. From the angles of macroscopic and microscopic respectively, the precision about 15 kinds of numerical simulation combination schemes in numerical simulation software was contrasted and analyzed. And the comprehensive evaluation indicator model of different evaluation items was established, the weight coefficients of two evaluation indicators could be calculated by using variation coefficient method from a point of view of objective weighing. The analysis results showed that numerical simulation accuracy of the enhanced wall function was higher and better. Firstly, on the basis of macroscopic evaluation indicator, the numerical simulation value of the enhanced wall function and RNG k-ε physical model could more accurately reflect the real flow rate of emitter, and the value of macroscopic evaluation indicator was 1.592%, which is minimal with the flow rate deviation ratio. Secondly, on the basis of the microscopic evaluation indicator, the fluid velocity deviation ratio using the enhanced wall function and SST k-ω physical model was minimal, and the value of microscopic evaluation indicator was 2.095%. Thirdly, the weight coefficients of macroscopic evaluation indicator and microscopic evaluation indicator were 0.6 and 0.4, respectively. Evaluating two indicators comprehensively, the value of comprehensive evaluation indicator of enhanced wall function and SST k-ω physical model was minimal, which was 2.031%. Further verifying the precision of the comprehensive evaluation indicator model, the comprehensive evaluation indicator between the measure value and numerical simulation value was 1.307%, which proved the accuracy and reliability of the comprehensive evaluation method about numerical si-mulation for two-ways mixed flow emitter. Using macroscopic evaluation indicator and microscopic evaluation indicator, and establishing comprehensive evaluation indicator method can provide an idea for analyzing the numerical simulation accuracy for two-ways mixed flow emitter.
