بررسي تاثير ورودي كليد پيانويي بر هيدروليك جريان در سريزهاي مدور قائم

چكيده انگليسي :

Effect of Piano Key Inlet on Hydraulics of Flow through Shaft Spillways Roya Shemshi r shemshykhuzani@cv iut ac ir January 19 2013 Civil Engineering Department Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor Abdorreza Kabiri Samani Email address akabiri@cc iut ac ir Abstract Intake vortices are the result of angular momentum conservation at the flow constriction where angular velocity increases with a decrease in the cross sectional area The common solution for avoiding air entrainment and swirl is to provide sufficient submergence to the intake If the required approach flow conditions can not be met to avoid swirl and air entrainment other approaches for preventing vortices at water intakes are considered There are several means for decreasing of swirling flow power where the most cost effective option is often determined by a physical model study Among the most economical and common measures of reducing the effect of air entrainment and swirl strength is the optimized shape of inlet for instance by installing a circular Piano Key inlet over the pipe intake If Piano Key inlet is used then its optimum geometry should be studied experimentally Since there is not any realized guidance for the use of circular Piano Key inlets on pipe intakes hence a comprehensive set of model experiments have been carried out using Piano Key inlets with different dimensions with respect to the vertical pipe intakes and two different pipe diameters of D 10 and 12 7 cm in cylinderical tank with two meter diameter and 1 meter hight In this study a comprehensive experimental investigation was performed to better understand the effects of Piano Key inlet geometry on discharge coefficient and threshold submergence in orifice flow The effects of the Piano Key inlet s geometric parameters including inlet length height and angle on shaft flow discharge coefficient and threshold submergence were investigated Also velocity profiles were taken by Acoustic Doppler Velocimeter ADV which moves in radius direction of the tank Results showed that by employing a Piano Key inlet over the vertical pipe intake the threshold submergence of orifice flow reduces significantly Determining the range of threshold submergence of orifice flow for all physical Piano key inlet is one of the propose of this study Fianally according to the results the effect of Piano Key inlet geometry on discharge coefficient of orifice flow were evaluated in the form of realized relationships which would be of practical interest for design engineers In addition an equation was proposed to determine the discharge coefficient of orifice flow of shaft spillway with Piano Key inlet Equations were developed by using the Statistical Package for the Social Sciences SPSS To check the correlations the normalized root mean square error NRMSE the weighted quadratic deviation WQD and the coefficient of determination R2 were considered Contrary to R2 both NRMSE and WQD must be small to have a good relation among parameters and the data Keywords Discharge coefficient Shaft spillways Threshold submergence of orifice flow Swirling flow Piano Key weir Experimental model

شمشي، رويا

بررسي تاثير ورودي كليد پيانويي بر هيدروليك جريان در سريزهاي مدور قائم

ضريب دبي , آستانه ي جريان روزنه اي , جريان گردابي , سرريز كليد پيانويي و مدل آزمايشگاهي