{"title":"A Computational Study of Very High Turbulent Flow and Heat Transfer Characteristics in Circular Duct with Hemispherical Inline Baffles","authors":"Dipak Sen, Rajdeep Ghosh","country":null,"institution":"","volume":102,"journal":"International Journal of Mechanical and Mechatronics Engineering","pagesStart":1046,"pagesEnd":1052,"ISSN":"1307-6892","URL":"https:\/\/publications.waset.org\/pdf\/10001772","abstract":"This paper presents a computational study of steady\r\nstate three dimensional very high turbulent flow and heat transfer\r\ncharacteristics in a constant temperature-surfaced circular duct fitted\r\nwith 900 hemispherical inline baffles. The computations are based on\r\nrealizable k-\u025b model with standard wall function considering the\r\nfinite volume method, and the SIMPLE algorithm has been\r\nimplemented. Computational Study are carried out for Reynolds\r\nnumber, Re ranging from 80000 to 120000, Prandtl Number, Pr of\r\n0.73, Pitch Ratios, PR of 1,2,3,4,5 based on the hydraulic diameter of\r\nthe channel, hydrodynamic entry length, thermal entry length and the\r\ntest section. Ansys Fluent 15.0 software has been used to solve the\r\nflow field. Study reveals that circular pipe having baffles has a higher\r\nNusselt number and friction factor compared to the smooth circular\r\npipe without baffles. Maximum Nusselt number and friction factor\r\nare obtained for the PR=5 and PR=1 respectively. Nusselt number\r\nincreases while pitch ratio increases in the range of study; however,\r\nfriction factor also decreases up to PR 3 and after which it becomes\r\nalmost constant up to PR 5. Thermal enhancement factor increases\r\nwith increasing pitch ratio but with slightly decreasing Reynolds\r\nnumber in the range of study and becomes almost constant at higher\r\nReynolds number. The computational results reveal that optimum\r\nthermal enhancement factor of 900 inline hemispherical baffle is\r\nabout 1.23 for pitch ratio 5 at Reynolds number 120000.It also shows\r\nthat the optimum pitch ratio for which the baffles can be installed in\r\nsuch very high turbulent flows should be 5. Results show that pitch\r\nratio and Reynolds number play an important role on both fluid flow\r\nand heat transfer characteristics.","references":null,"publisher":"World Academy of Science, Engineering and Technology","index":"Open Science Index 102, 2015"}