مطالعه تجربي جريان روي دوسازه سه بعدي پشت سر هم تحت زاويه با استفاده از تونل باد و تونل دود

چكيده انگليسي :

108 Experimental Investigation on the Flow over Two Tandem Three Dimensional Square Prisms at Incidence Using Wind Tunnel Smoke Tunnel Mohammad Jafarzadeh m jafarzadeh@me iut ac ir Date of Submission 08 10 2015 Department of Mechanical Engineering Isfahan University of Technology Iran Degree M Sc Language Farsi Supervisor Ahmad Sohankar asohankar@cc iut ac ir AbstractThe flow over bluff bodies in tandem side by side or staggered arrangements represents animportance and complex configuration that is of interest for many engineering applications suchas tall buildings adjacent skyscrapers groups of chimney stacks tubes bundles in heatexchangers overhead power line bundles bridge piers stays masts chemical reaction towers off shore platforms and electronic systems especially in computer equipment For theseconfigurations the flow interference has an essential role for several changes in the characteristicsof the flow Thus the dynamic interaction between the structure and the fluid is one of the mostfascinating problems in engineering mechanics Various studies including both numerical andexperimental investigations have been conducted for the ow over two dimensional squarecylinders in different arrangements where the effects of floor wall and roof free flow of thecylinders are not included In reality most of cylindrical structures such as buildings have finiteheight with a wall in one end and free flow in another end This case is a type of threedimensional bodies When an object is in the wake of another flow properties and aerodynamicforces are affected by geometry distance between two structures and their placement toward theflow In this research the flow around two tandem square cylinders with limited height same astwo tandem buildings is studied experimentally by using wind tunnel and smoke tunnel Experiments were performed in Isfahan University of Technology labs The aspect ratio of themodels side height is 7 The distance between the models is varied between 1D to 5D where Dis cylinder side and the incidence angle is varied between zero to 45 degree The pressurecoefficients Cp on the models faces are measured via 53 sensors which are placed on theirs faces In this test the Cp is measured in different gap distances and angles of attack The flowpatterns around two cylinders are investigated by smoke visualization for different gap spacingand angles of attack Measuring velocity field and turbulence quantities around two tandemsquare cylinders are carried out using hot wire anemometry for various gap distances Results ofthis study show that the three dimensional of the geometry and variations of the gap distance andangle of attack have important effects on the flow patterns and pressure and velocity quantities Three major regimes are distinguished according to the gap spacing between cylinders that is thesingle slender body regime the reattach regime and co shedding or binary vortex regime Also itwas found that the results for three dimensional cylinders differ from those are reported for twodimensional cylinders Some similarity is observed between results of the two dimensionalcylinders and those for the middle plane of three dimensional cylinder where the effects of thefloor and roof of the models on the results of this plane are small This study shows that the meanresults are relatively independent to Reynolds numbers considered in this work Also byincreasing the distance between two cylinders the interaction is reduced and therefore the resultsof the upstream cylinder is almost the same as the single cylinder Keywords Experimental study two tandem three dimensional square cylinders wind tunnel smoke tunnel attack angle turbulent flow

جعفرزاده، محمد

مطالعه تجربي جريان روي دوسازه سه بعدي پشت سر هم تحت زاويه با استفاده از تونل باد و تونل دود

دو سيلندر سه بعدي پشت سر هم , زاويه حمله , جريان آشفته