Experimental Investigations And Numerical Simulations On The Discharge Capacity And The Hydraulic Characteristics Of Oblique Practical Weir

Oblique practical weirs are often the designer's choice for mid-scale and small-scale water conservancy projects that are limited by natural riverbed boundary conditions,but their discharge capacity is still a technical issue.This paper is based on the flood control project of the Caocun of the Yanchang petroleum Plant in Shaanxi Province,study on practical oblique weir with different oblique angle and different discharge.Physical model test method,theoretical analysis and numerical simulation method are adopted.The results show that:1.Combining with practical engineering,the importance is put forward and the research status is summarized of oblique practical weir.On the basis of traditional oblique weir,the layout of downstream channel is improved,and two functions affecting the overflow capacity of practical oblique weir are put forward.2.There are failure conditions in traditional oblique weirs.But the model test results shows that the water head of the oblique practical weir in this study are lower than that of the orthogonal weir under the condition of equal channel width.Obviously,the overflow capacity of practical oblique weir are increased.3.The upstream flow velocity head of the oblique practical weir are larger than that of the orthogonal weir under the condition of equal channel width.However,when the oblique practical weir operates at low water head,the changing trend of flow velocity is opposite to that at high water head.It shows that low water head is a special and advantageous operation condition for oblique weir.4.The upstream flow field characteristics of oblique weir are analyzed in detail.And according to the results of numerical simulation,there will be no circulation zone similar to the side weir in upstream,the mainstreams are deflected.The magnitude of deflect is affected by the flow rate.5.Through the theoretical analysis method,relevant factors affecting discharge coefficient of oblique practical weir are found out.And combining with model test data,the formula for calculating discharge coefficient of practical oblique weir is fitted.The formula is simple in form,high in accuracy and convenient for engineers to use.6.The results of model test and numerical simulation are compared to prove that the numerical simulation method for oblique weir with FLOW-3D software is feasible.The accuracy of the formula for calculating the discharge coefficient of the practical oblique weir is verified again.And the analysis of the two effects on the overflow capacity of oblique practical weirs has been proved to be reasonable.