An experimental flow field and heat transfer investigation of submerged double-sided reattachment and two dimensional impingement Slot Jets /
Reattachment nozzles have great potential for heating, cooling, or drying applications in process industries due to their favorable transport characteristics. This research investigates sub-sonic, turbulent, submerged impingement jet flow field and associated heat transfer from two nozzles: a 0⁰ exi...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
2001.
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| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=726104671&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Reattachment nozzles have great potential for heating, cooling, or drying applications in process industries due to their favorable transport characteristics. This research investigates sub-sonic, turbulent, submerged impingement jet flow field and associated heat transfer from two nozzles: a 0⁰ exit angle Slot Jet Reattachment (SJR) nozzle and a Slot Jet (SJ) nozzle. Both these nozzles are comprised of a rectangular region of aspect ratio 20:1 with circular ends. The 0⁰ SJR nozzle has an additional bottom plate that causes the flow to exit the nozzle parallel to an adjacent flat impingement surface. It is essentially a double-sided reattachment jet with unconfined circular ends. Detailed heat transfer, impingement surface pressure and flow field measurements are presented for both nozzles. The documented quantities include mean velocities, rms Reynolds normal and shear stresses in the plane of measurement, two-dimensional contour maps of local heat transfer distribution, and mean and rms surface pressures. Four case studies are presented in detail- two for each nozzle at different nozzle-to-surface spacings. Contours of local heat transfer for the SJR nozzle exhibit three- dimensionality within the recirculation and reattachment regions, which increases with nozzle-to-surface spacing. Flow field measurements at close spacing indicate that high heat transfer in the reattachment region could be caused by high near-wall streamwise and shear Reynolds stresses, coupled with an intermittent flow impingement on the surface due to high normal Reynolds stress. At farther nozzle-to-surface spacing, the streamwise Reynolds stress is the primary turbulent quantity affecting heat transfer. In both cases, the jet curtain is unsteady due to high normal Reynolds stress in the lower side of the jet. A non-dimensional scheme for generalized representation of heat transfer data for separated/reattaching jet flows is developed and demonstrated. It is based on a length scale that approximates the jet path, along with a factor that accounts for the finite aspect ratio of the SJR nozzle. A new qualitative technique for air flow visualization using infrared thermography is developed. The air flow is seeded with trace quantity of sulfur hexafluoride gas for detection by an infrared camera. |
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| Item Description: | Vita. "Major Subject: Mechanical Engineering". |
| Physical Description: | xxviii, 274 leaves : illustrations ; 28 cm. + 1 CD ROM. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 264-272). |