Showing papers by "Terrence W. Simon published in 2017"

Turbulent flow characteristics and heat transfer enhancement in a rectangular channel with elliptical cylinders and protrusions of various heights

Abstract: This numerical study investigates turbulent flow characteristics and heat transfer augmentation in a rectangular channel with elliptical cylinders and protrusions. The height of protrusions...

Progress in thermal transport modeling of carbonate-based reacting systems

Abstract: Purpose Carbonate-based heterogeneous reacting systems are investigated for the applications of thermochemical carbon dioxide capture and energy storage. This paper aims to review recent progress in numerical modeling of thermal transport phenomena in such systems. Design/methodology/approach Calcium oxide looping is selected as the model carbonate-based reacting system. Numerical models coupling heat and mass transfer to chemical kinetics are reviewed for solar-driven calcium oxide looping on the sorbent particle, particle bed, and reactor levels. Findings At the sorbent particle level, a transient numerical model of heat and mass transfer coupled to chemical kinetics has been developed for a single particle undergoing cyclic calcination and carbonation driven by time-periodic boundary conditions. Modeling results show cycle times impact the maximum sorbent utilization and solar-to-chemical energy efficiency. At the reactor level, a model of heat and mass transfer coupled to chemical kinetics of calcination of a packed-bed reactor concept has been developed to estimate the reactor’s performance. The model was used to finalize reactor geometry by evaluating pressure drops, temperature distributions, and heat transfer in the reactor. Originality/value Successful solar thermochemical reactor designs maximize solar-to-chemical energy conversion by matching chemical kinetics to reactor heat and mass transfer processes. Modeling furthers the understanding of thermal transport phenomena and chemical kinetics interactions and guides the design of solar chemical reactors.

A Solar Reactor Design for Research on Calcium Oxide-Based Carbon Dioxide Capture

Abstract: Leanne Reich has been supported by the U.S. National Science Foundation Graduate Research Fellowship (Grant No. 00006595)

Numerical simulation and analysis of hybrid physical-chemical vapor deposition to grow uniform perovskite MAPbI3

Abstract: Applications of metal halide perovskite have been rapidly developing in recent years. However, very little research focusing on basic growth kinetics of perovskite films can be found in the literature. This paper discusses a hybrid physical-chemical deposition process of planar perovskite films. A 2-D ANSYS Fluent simulation is presented to calculate the heat and mass transfer during the deposition process. An optimized mass flow configuration with a flow resistance imposed by a porous screen is shown to give a uniform distribution of the methylammonium iodide vapor precursor and an even surface deposition rate of perovskite films. Both steady and transient calculations indicate that increasing operating temperature or vessel pressure within certain limits can boost the surface deposition rate of perovskite. Limitations on working pressure are presented for preventing reverse flow into the chamber and associated deterioration of deposition uniformity of the perovskite films.

Computational fluid dynamics modeling patterns and force characteristics of flow over in-line four square cylinders

Abstract: The flow over four square cylinders in an in-line, square arrangement was numerically investigated by using the finite volume method with CFD techniques. The working fluid is an incompressible ideal gas. The length of the sides of the array, L, is equal. The analysis is carried out for a Reynolds number of 300, with center-to-center distance ratios, L/D, ranging from 1.5 to 8.0. To fully understand the flow mechanism, details in terms of lift and drag coefficients and Strouhal numbers of the unsteady wake frequencies are analyzed, and the vortex shedding patterns around the four square cylinders are described. It is concluded that L/D has important effects on the drag and lift coefficients, vortex shedding frequencies, and flow field characteristics.

Injection Angle Influence of Secondary Holes on the Enhancement of Film Cooling Effectiveness With Horn-Shaped or Cylindrical Primary Holes

Abstract: Secondary holes to a main film cooling hole are used to improve film cooling performance by creating anti-kidney vortices. The effects of injection angle of the secondary holes on both film cooling effectiveness and surrounding thermal and flow fields are investigated in this numerical study. Two kinds of primary hole shapes are adopted. One is a cylindrical hole, the other is a horn-shaped hole which is designed from a cylindrical hole by expanding the hole in the transverse direction to double the hole size at the exit. Two smaller cylindrical holes, the secondary holes, are located symmetrically about the centerline and downstream of the primary hole. Three compound injection angles (α = 30°, 45° and 60°, β = 30°) of the secondary holes are analyzed while the injection angle of the primary hole is kept at 45°. Cases with various blowing ratios are computed. It is shown from the simulation that cooling effectiveness of secondary holes with a horn-shaped primary hole is better than that with a cylindrical primary hole, especially at high blowing ratios. With a cylindrical primary hole, increasing inclination angle of the secondary holes provides better cooling effectiveness because the anti-kidney vortices created by shallow secondary holes cannot counteract the kidney vortex pairs adequately, enhancing mixing of main flow and coolant. For secondary holes with a horn-shaped primary hole, large secondary hole inclination angles provide better cooling performance at low blowing ratios; but, at high blowing ratios, secondary holes with small inclination angles are more effective, as the film coverage becomes wider in the downstream area.Copyright © 2017 by ASME

Enhanced Film Cooling Effectiveness by Integration of Horn-Shaped and Cylindrical Holes

Abstract: In search of improved cooling of gas turbine blades, the thermal performances of two different film cooling hole geometries (horn-shaped and cylindrical) are investigated in this numerical study. The horn-shaped hole is designed from a cylindrical hole by expanding the hole in the transverse direction to double the hole size at the exit. The two hole shapes are evaluated singly and in tandem. The tandem geometry assumes three configurations made by locating the cylindrical hole at three different positions relative to the horn-shaped hole such that their two axes remain parallel to one another. One has the cylindrical hole downstream from the center of the horn-shaped hole, a second has the cylindrical hole to the left of (as seen by the flow emerging from the horn-shaped hole) and at the same streamwise location as the horn-shaped hole (θ = 90°) and the third has an intermediate geometry between those two geometries (downstream and to the left of the horn-shaped hole - θ = 45°). It is shown from the simulation results that the cooling effectiveness values for the θ = 45° and 90° cases are much better than that for θ = 0° (the first case), and the configuration with θ = 45° exhibits the best cooling performance of the three tandem arrangements. These improvements are attributed to the interaction of vortices from the two different holes, which weakens the counter-rotating vortex pairs inherent to film cooling jet to freestream interaction, counteracts with the lift forces, enhances transverse tensile forces and, thus, enlarges the film coverage zone by widening the flow attachment region. Overall, this research reveals that integration of horn-shaped and cylindrical holes provides much better film cooling effectiveness than cases where two cylindrical film cooling holes are applied with the same tandem configuration.Copyright © 2017 by ASME