4903

4606

كارشناسي ارشد

آب

اصفهان: دانشگاه صنعتي اصفهان، دانشكده عمران

1388

ده،115ص: مصور،جدول، نمودار

ص.ع. به: فارسي و انگليسي

عبدالرضا كبيري ساماني

محمد كريم بيرامي

16/10/88

محمود برقعي، محمد رضا چمني

1396/09/22

كتابنامه

مهندسي عمران

ID4606

به فارسي و انگليسي: قابل رويت در نسخه ديجيتال

Effective Hydraulic Parameters on Discharge for Oblique Weirs Ahmad Ansari Ahmad815@cv iut ac ir April 25 2009 Department of Civil Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Abdoreza kabiri samani a kabiri@cc iut ac irAbstract Weirs are among the most popular and simple hydraulic structures They can be used for various purposes especially as flow measuring devices in canals irrigation systems and environmental projects and can beencountered in real life in various types and shapes If the weir plate is placed verticaly to the bottom of thechannel and angled to the channel walls is named an oblique weir One easy and practical way to reducethe head for higher discharge with the limiting channel width and less energy loss would be oblique weir For restricted channel width the weir is placed obliquely to the flow hence the effective weir length isincreased beyond the channel width and results to decrease of water head or increase of the efficiency ofthe weir Also unlike full width weir an oblique weir automatically aerated by diverting the flow throughpassing over the weir hence no aeration is needed to assure a free flow There is a wide knowledge onperpendicular weirs but few studies have been done on weirs placed obliquely to the flow direction obliqueweirs In this study a comprehensive set of experiments is performed on weirs placed obliquely in an openchannel Since the previouse reaserchs have limitations on the angel of obliquness from 0 to 64 degrees and small ratios of H P H is the upstream water head and P is the weir height relative to upstream channelbed elevation hence the main objectives of this study is to investigat different wier obliqueness differentH P behavior and hydraulic characteristic of flow and examining methods for increasing the dischargecapacity and effective length of oblique weirs Experiments were conducted on oblique weirs with differentangles from 0 to 80 or L B 1 012 to L B 5 75 for both free and submerged flow The effective crestlength and threshold submergence the first effective downstream water head above the weir crest to theupstream water head are the other objectives of this study Also different combinations of weir angle guide vanes and upstream inclined plates were examinedand the effects of each combination on increasing the discharge over the weir compared with the results ofnormal weir were determined Results show that the flow always tends to keep its direction to nearlyperpendicular to the weir crest when it reaches and passes the weir By increasing the oblique angle theeffective length of the weir increases significantly whereas the discharge coefficient Cd slightly decreases Finally practical relations and design recommendations are presented on the discharge coefficient ofoblique weirs the effective length of oblique weir threashold submergence and the use of guide vanes andinclined plates It is seen that applying a group of 2 vane plates in upstream face of the weir under the watersurface can increase the water dischrge upto 20 and by using the inclined plate the flow discharge canincrease upto 25 Similar analysis has been done on the effect of both devices on increasing the effectivelength of the weir It is shown that guide vanes and inclined plate can increase the effective length upto15 and 20 respectively Key Words Oblique Weir Experimental Model Discharge Coefficient ThreasholdSubmergence Effective Length Guide Vanes Inclined Plate

عبدالرضا كبيري ساماني

محمد كريم بيرامي

محمود برقعي، محمد رضا چمني