Heat Transfer Laboratory

Faculty: Dr. Richard J. Goldstein

Rajat Mittal

Title: Experimental Verification of Heat and Mass Transfer Analogy in Turbulent Separated Flows over a Backward Facing Step

Abstract

• Heat transfer and fluid flow in separated flows are frequently encountered in various engineering applications. Some examples include microelectronic circuit boards, combustors, heat exchangers, axial and centrifugal compressor blades and gas turbine blades. Important parameters which affect these flows include: variation of thermal and fluid properties, turbulence intensity and thermal boundary conditions. Previous studies have been conducted to isolate these parameters to have a greater understanding of the impact of individual effects. In spite of these simplifications, the heat transfer measurements are prone to error due to wall conduction and radiation effects.

• A solution to the above can be the transformation of the heat transfer problem into an analogous mass transfer situation using the naphthalene sublimation technique.

• The success of the aforementioned solution hinges on the existence and determination of an analogy factor that can transform the transport coefficients from the mass transfer to the heat transfer domain. The analogy factor, which can either be a simple constant or a complicated function of flow parameters, has been verified for laminar and turbulent flows.

• However, the analogy is yet to be verified for separated flows. Subsequently, the goal of the present study is to experimentally prove the existence of an analogy and obtain an analogy factor for separated flows.

• Owing to its geometrical simplicity and ability to capture the basic features of separated flows: separation, reattachment, recirculation and development of free-shear layers, the flow over a backward facing step (BFS) is chosen to investigate the heat and mass transfer analogy in separated flows.