Prioritizing Design Parameters for Stepped Chutes and Shear Stress Distribution

Water

Saeed Akbari¹  Khosro Morovati²  Fuqiang Tian²  Christopher Homer³  Hosein Ghaedi³ 

[1] Center of Research in Enhanced Oil Recovery (COREOR), Petroleum Engineering Department, Universiti Petronas, Seri Iskandar, Toronoh 32610, Malaysia;Department of Hydraulic Engineering, Tsinghua University, Beijing 100084, China;School of Environment Engineering, Tsinghua University, Beijing 100084, China;

关键词: ANOVA;    numerical simulation;    stepped chutes;    prioritization;    shear stress;   

DOI  :  10.3390/w13091155

来源: DOAJ

【 摘 要 】

Stepped chutes offer high efficiency in decreasing flow velocity due to roughness; however, negative impacts may still be experienced by the receiving water body into downstream. These effects might be mitigated if geometric and hydraulic parameters governing the structure are well addressed. Herein, five influential parameters were developed, i.e., longitudinal slope S (S = tan θ), discharge (Q), pool height above steps (h_p), chute width (W), and chute height (H), employing a three dimensional (3D) numerical model. Through 600 simulations, two regression models were developed for predicting depth-averaged velocity at the last step V_d (m/s) and critical length L_c (cm) at the downstream where the maximum velocity occurs, using response surface methodology (RSM) based on the mixed-level full factorial design. The prediction data obtained by developed regression models were agreeable with actual data with coefficient determination (R²) of about 0.95, highlighting the accuracy and ability of the models for the prediction of V_d and L_c. Additionally, the analysis of variance (ANOVA) was used to prioritize the impact of the studied parameters on V_d and L_c. Results highlighted that among geometric parameters, W and $S$ had a significant influence on V_d and L_c; however, the impact of W was more pronounced. Using a regression model for L_c, a cross section was obtained, and the shear stress distribution of the downstream was compared with that of the last step and sidewalls. The shear stress patterns showed that the maximum value shifted from the side walls to the downstream between the lower and higher slopes. Further, the longitudinal distribution of shear stress at the downstream revealed that geometric and hydraulic characteristics played a negligible role in the changing pattern of shear stress. The results of this study reveal the dynamic behavior of the given structure where different geometric options are available for structure design.

【 授权许可】

Unknown