Mysak P. Methods of hydraulic calculation of point-type stormwater inlets

Stormwater drainage systems are the critical component of urban engineer infrastructure. The level of wellbeing in developed areas, safety on transportation routes, and the ecological state of adjacent surface water bodies depend on the efficiency of their operation. Inlet devices of various types and designs are essential elements of stormwater drainage networks, they ensure the collection of all types of surface runoff (stormwater, meltwater, and street washing runoff) directly from adjacent surfaces. Therefore, an important task is to provide proper hydraulic characteristics of inlet structures, which allow for the effective collection of surface runoff, thus preventing urbanized areas from flooding. A methodology for conducting experimental studies of stormwater inlets and a methodology for mathematical processing of their hydraulic characteristics to obtain capacity at a head of 20 mm, values of transition heads and flow rates corresponding to transitions between the BCW mode, combined mode, and orifice mode, as well as discharge coefficients in different operating modes, has been developed Criteria for the presence of free and surcharged flow types through the 'inlet – outlet pipe' system have been substantiated. Criteria for determining the BCW mode, combined mode, and orifice mode for non-surcharged flows have been established. The experimental part of the study involved a full-scale verification of the corresponding theoretical results and refinement of the numerical values of discharge coefficients for point-type inlets in the BCW mode, as well as in combined mode, and orifice mode. Experimental discharge-head characteristics of the Basic 400 inlet with a 200 mm diameter outlet pipe were obtained, as well as of the wastewater gullies with horizontal outlets of 100 mm and 200 mm diameters and a plate-type hydraulic siphon for the grates of various types and sizes. The change in the flow pattern through the stormwater inlet with bar gratings was studied as the inflow discharge increased. The main flow patterns characteristic of the BCW mode, combined mode, and orifice mode are described. Based on the obtained theoretical and experimental results, an improved method for hydraulic calculation of point-type stormwater inlets has been developed, taking into account the flow type through the stormwater inlets and the flow mode through the grating for non-submerged flows. The algorithm for hydraulic calculation of point-type stormwater inlets includes the determination of transit heads and discharges, as well as the application of the flow-head characteristics structure and corresponding discharge coefficients for the BCW mode, combined mode, and orifice mode. Thus, the dissertation has addressed the important scientific and practical task of improving existing methodologies for hydraulic calculations of point-type stormwater inlets, taking into account variable hydraulic operating conditions. The obtained results of the study provide a better understanding of the hydraulic parameters of stormwater inlets, which have a significant impact on the reliability and effectiveness of stormwater drainage networks. This is especially important given the constant increase in urbanization and considering global climate changes.