Location Of Inception Point Research Articles

Location of inception point of alternating steps stepped spillways

This study explored the effects of flat-stepped spillways having alternating steps on the inception point location. Two wooden stepped spillways with a longitudinal slope of 26.6° were constructed in a rectangular flume and tested at various discharges, ranging from 0.003 to 0.05 m3/s. Each model had twenty-seven steps, and the channel's width, depth, and length were 0.605 meters, 1.35 meters, and 8 meters. The outcomes showed that the Alternating Model (MA), compared to the Regular Model (MR), has shortened the inception point distance (Li) from the downstream crest of the spillway by an average of 27% (e.g., the Li of the MR model was 59 cm, and the Li of the MA model was 43 cm). The MA model's skimming flow was discovered to begin at higher discharges, at yc/h 1.24 (as opposed to yc/h=0.98 for the MR model). Two equations were also developed to compute the inception point positions for flows over the MA and MR stepped spillways.

Numerical Study to Evaluate the Performance of Nonuniform Stepped Spillway Using ANSYS-CFX

The main features that attract hydraulic engineers for designing stepped spillways are their ability to lose a large portion of the flow energy and add or increase aeration to the flow naturally. Hence, smaller size stilling basin and no aeration device may require. This study aims to find the amount of energy dissipation rate and the location of inception point over non-uniform stepped spillway. The numerical 2D ANSYS-CFX code is applied to generate and run thirty-two models of different configurations using two different moderate slopes (1 V:2 H and 1 V:2.5 H) as most of the downstream slopes designed for moderate slope, and two different step heights (hs= 0.08 m and hs= 0.016 m) under skimming flow discharge for different (dc/hs) ranging from dc/hs= 1–2.2, in which dc is the critical flow deptho n the crest. The volume of fluid is implemented and the renormalized group of k-ɛ turbulence model is activated. The computational results demonstrated that the amount of energy dissipation increases with decreasing the flow discharge, chute slope, and step height. In addition, it is observed that the length of the inception point is directly proportional to the discharge and inversely proportional to both the chute slopes and step height. Moreover, for the design point of view, the results revealed that configuration B can be considered as the optimal one amongst the others examined herein.

Inception point of flow aeration on quarter-circular crested stepped spillway

The aim of this study was to investigate the location of inception point of flow aeration (LIPFA) on quarter-circular crested stepped spillway (QCSS). The QCSS is a typical stepped spillway the crest geometry of which consists of a quarter circle. To this purpose, a series of experiments were programmed. Dimensional analysis showed that the slope of the downstream stepped chute, step size and flow discharge are the effective parameters in the LIPFA. In this study, three values of 0.1 m, 0.15 m and 0.2 m were considered for the crest radius of QCSS. The heights of stepped spillways were as 0.05 m, 0.08 m and 0.10 m and lengths of steps were as 0.05 m, 0.10 m, and 0.15 m. Considering the step size, the four slopes for the downstream stepped chute were obtained at 0.33, 0.50, 1.0 and 1.60. The slopes of stepped chute changes from 0.33 to 1.6. The number of steps was 8, 10 and 16. Results showed that as flow rate increases, the distance of the LIPFA from the crest increases as well. By half the size of steps, the length of the non-aerated area increases by more than sixty percent. With an increase of one hundred percent slope, the length of the aerated area increases by more than 20%. In general, the reducing of the slope of the stepped spillway leads to decrease the length of the area of non-aerated, and also refining the size of steps leads to scrolling the location of inception point of aeration to the downstream.

The Effect of the Step Height on Energy Dissipation in Stepped Spillways Using Numerical Simulation

From 1970s, studies have been conducted on the hydraulic design of stepped spillways and many empirical formulas were developed. Despite the simple geometry of these spillways, their hydraulic behavior is complicated. As a result, for many cases, the physical models are studied to verify the design. Numerical simulation is considered as a tool to reduce the laboratory tests, in order to save time and money. Furthermore, the parameters which are not investigated or measured in physical models could be evaluated. In this paper, the results of numerical simulations are compared with the results of physical models and empirical formulas for the spillway of Renwick dam studied in a 1/8 scale model by Hunt and Kadavy (World Environmental and Water Resources Congress. ASCE, Great Rivers, pp. 3061–3071, 2009). Numerical simulation of flow is achieved by a mixture multi-phase flow model and a realizable k-\({\varepsilon}\) turbulence model proposed by Qian et al. (Sci China Ser E-Tech Sci 52(7), 1958–1965, 2009). Grid sensitivity is accomplished and the size of mesh is reduced in locations where a high gradient of certain parameters exists or a higher precision is required. The numerical simulation results conform to the physical model tests. The velocity profile, energy dissipation, and the location of inception point where air entrainment in the flow is guaranteed, are investigated and compared to the scale model results. Also, thanks to this satisfaction, we could obtain the parameters such as pressure field which are not measured in the physical model.