Terrence W. Simon

Bio: Terrence W. Simon is an academic researcher from University of Minnesota. The author has contributed to research in topics: Heat transfer & Turbulence. The author has an hindex of 37, co-authored 305 publications receiving 5025 citations. Previous affiliations of Terrence W. Simon include Motorola & DuPont.

Separation Control using Plasma Actuators: 2-D and Edge Effects in Steady Flow in Low Pressure Turbines

Abstract: A Dielectric Barrier Discharge plasma actuator is o perated in quiescent air and in flow over a Low Pressure Turbine (LPT) airfoil at a Reynolds number of 50,000 (based on exit velocity and suction surface length) and inlet free -stream turbulence intensity of 2.5%. Measurements of velocity and total pressure are taken with constant and intermittent operation of the actuator to study the effects of e xcitation frequency and amplitude on flow velocity, and the effects of the intermittent signa l parameters on separation control. LPT measurements are also taken with opposite and aligned actuator orientations, and downstream of the span-wise plasma discharge edge. The objectives of this paper are: a) to investigate the authority of the plasma actuator fo r control of bypass transition and separation of low Reynolds number flows in LPT airfoil geometries, b) to comment on the relationship between separation control and frequency of disturbance, and c) to examine the role of three-dimensional vortical disturbances on separation control. Control is demonstrated with the actuator imparting momentum opposite to the flow direction, showing that it is possible to use disturbances alo ne to destabilize the flow and effect transition. No frequencies of strong influence are found over the range tested, indicating that a broad band of effective frequencies exists. Edge effects are found to considerably enhance separation control.

Conjugate Heat Transfer Predictions on Combined Impingement and Film Cooling of a Blade Leading Edge Model

Abstract: In this paper, numerical simulation is performed to predict combined impingement and film cooling on a model of the turbine blade leading edge by the heat flow coupling method. The first-stage roto...

Effects of Channel Aspect Ratio on Convective Heat Transfer in an Electronics Cooling Heat Sink Having Agitation and Fan-Induced Throughflow

Abstract: Fan-driven throughflow is frequently used for convective cooling of electronics. Channels with walls behaving like fins are common. In the present study, the flow inside the channels is agitated by means of translationally oscillating plates called agitators. Effectiveness of agitation by oscillating blades is found to be dependent on the channel width, a parameter studied herein. Heat sinks having narrower channels have a greater number of channels in total for the fixed size of heat sink and therefore greater heat transfer area than heat sinks with wider channels. Thus, with the same channel height, as the aspect ratio increases, channel width decreases, and it is found that opportunities for agitation are reduced and the generated turbulence is more strongly damped, thus reducing heat transfer coefficients. A study was carried out to find direction toward an optimal number of channels for a given heat sink using the agitation strategy. As part of the study, fluid damping and power consumption to drive the agitator assembly were addressed. The study was done numerically using ANSYS FLUENT on a representative single channel of the heat sink and the results were extended to the full size, multiple-channel heat sink system. Recommendations for moving toward an optimum geometry, based on thermal performance and agitator power are made.© 2013 ASME

Effects of dissolved gases on subcooled flow boiling from small heated regions with and without streamwise concave curvature

Abstract: Coolants such as fluorocarbon liquids usually contain high levels of dissolved gases. When heated, these gases are liberated from the liquid; if the liquid is boiling, these gases may influence the supply of liquid to the boiling surface. In this study, the effects of dissolved air in perfluorinated hydrocarbon, FC-72, on flow boiling heat transfer characteristics were experimentally investigated over a range of heat flux from the onset of nucleate boiling (ONB) to the critical heat flux (CHF). The experiments were conducted in both straight and curved channels. The boiling surface was a 3 mm/spl times/3 mm patch located on the channel wall. In the curved flow, it was located at the 90/spl deg/ position of a U-bend on the concave wall. Gas content was varied from 1.16/spl times/10/sup -5/ to 2.55/spl times/10/sup -3/ mole/mole, velocity ranged from 0.8 to 6.9 m/s, and pressure was controlled to either 1.41 or 1.92 atm. Subcooling, based on total pressure, was maintained at 27.5/spl deg/C. The data show that reduction of incipience superheat at ONB due to dissolved gases under these forced-convection conditions is much less than with pool boiling or low-velocity flow boiling. Boiling curves for gassy and degassed cases differ at low heat flux levels but merge at higher heat fluxes. The merging may indicate that the near-wall liquid layer is being degassed at higher heat fluxes. Though the high-heat-flux portions of the boiling curves were apparently unaffected by the content of dissolved gas in the approaching liquid stream, the critical heat flux was decreased by as much as 10%. Explanations of this behavior are presented in terms of the two mechanisms for the liquid supply to the macrolayer. >

Boundary Layer Theory

Abstract: The boundary layer equations for plane, incompressible, and steady flow are $$\matrix{ {u{{\partial u} \over {\partial x}} + v{{\partial u} \over {\partial y}} = - {1 \over \varrho }{{\partial p} \over {\partial x}} + v{{{\partial ^2}u} \over {\partial {y^2}}},} \cr {0 = {{\partial p} \over {\partial y}},} \cr {{{\partial u} \over {\partial x}} + {{\partial v} \over {\partial y}} = 0.} \cr }$$

Numerical Heat Transfer And Fluid Flow

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Assessment of high-heat-flux thermal management schemes

Abstract: This paper explores the recent research developments in high-heat-flux thermal management. Cooling schemes such as pool boiling, detachable heat sinks, channel flow boiling, microchannel and mini-channel heat sinks, jet-impingement, and sprays, are discussed and compared relative to heat dissipation potential, reliability, and packaging concerns. It is demonstrated that, while different cooling options can be tailored to the specific needs of individual applications, system considerations always play a paramount role in determining the most suitable cooling scheme. It is also shown that extensive fundamental electronic cooling knowledge has been amassed over the past two decades. Yet there is now a growing need for hardware innovations rather than perturbations to those fundamental studies. An example of these innovations is the cooling of military avionics, where research findings from the electronic cooling literature have made possible the development of a new generation of cooling hardware which promise order of magnitude increases in heat dissipation compared to today's cutting edge avionics cooling schemes.