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چكيده انگليسي :

Swirling Flow Characteristics at Vertical Shaft Spillways Using Marguerite Shape Inlet Amin Teimouri Aghcheh amin teimouri@cv iut ac ir Date of Submission May 26 2015 Department of Civil Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiSupervisors Dr Abdorreza Kabiri Samani akabiri@cc iut ac ir AbstractVertical shaft spillways especially the most common form namely morning glory spillways have been widelyused in a number of dam projects since the late 19 th century around the world Although a number of studiesoriented to the shape of the inlet of shaft spillways including bell mouth inlet there are lack of research studiesregarding to the inlet shape of these hydraulic structures A brief review of researches in this field shows thatmost of the former studies have focused on the bell mouth inlet to enhance the flow field thereby increasingthe capacity using complementary structural elements such as anti vortex plates trashracks etc Thus thedesign of morning glory spillways with bell mouth shaped inlet has been experienced by design engineers Improving the hydraulic performance of different types of spillways was a major objective of several studies resulting in different forms of spillway crests such as piano key weirs and daisy shaped inlets Daisy marguerite shaped inlets which are the subject of the present study have been applied in some dam projects Applying this type of inlet with a specified form of intake structure results in increasing the crest length of thespillway for a given vertical shaft spillway and effectively prevents the swirling flow and air core vortices Present study follows the former studies on daisy marguerite shaped spillways which have been conductedin the department of Civil Engineering Isfahan University of Technology Former studies have been focusedon the flow hydraulic characteristics through this type of spillways by a radial inflow and the crest controlflow regime However due to the lack of sufficient information about the hydraulic characteristics of flowaround the marguerite shaped spillways in the case of swirling flow the present study was performed Inrespect to the asymmetry location of the vertical shaft spillways in the dam reservoirs usually radial flowaround the spillway is not a realized case instead tangential flow behavior should be taken into account toanalyze the hydraulic performance of these spillways Experimental study was conducted in a hydraulic model of vertical shaft spillway equipped with themarguerite shaped inlets The flow discharges were ranged among crest control orifice flow control andcompletely filled pipe flow on models of marguerite spillways with different geometries including the length height and umber of blades Accordingly the effects of spillways geometries on swirling flow changing theflow regimes the discharge coefficient and etc have been quantified Tests were performed in a circularcylinder of 2 meter in diameter and 1 m high To create swirling flow condition the flow was enteredtangentially through a vertical inlet installed on the reservoir s wall Three dimensional flow velocities weremeasured by an ADV installed over the reservoir with Frequency of 200Hz The water free surface profile wasmeasured using piezometers installed under the reservoir floor Results indicated that by increasing the length and height of the blades of a marguerite spillway the swirlingflow tangential velocity decreases whereas the flow discharge increases Also increasing the length heightand number of blades results in the delay of air core vortex formation even in some geometries eliminates theair core vortex Dimensionless parameters were used to quantify the results and finally a correlation wasderived for flow discharge coefficient of the marguerite spillways using statistical analysis Keywords vertical shaft spillway morning glory marguerite spillway air core vortex hydraulicmodel flow regime swirling flow discharge coefficient

تيموري آغچه، امين

بررسي ويژگي هاي جريان گردابي در سرريزهاي مدور قائم با ورودي گلبرگي شكل

ورودي نيلوفري , سرريز گلبرگي , گرداب داراي هسته هوا , مدل هيدروليكي , رژيم جريان , جريان چرخشي , ضريب دبي