Author
L. W. Florschuetz
Bio: L. W. Florschuetz is an academic researcher from Arizona State University. The author has contributed to research in topics: Heat transfer & Orifice plate. The author has an hindex of 13, co-authored 15 publications receiving 1147 citations.
Papers
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TL;DR: In this article, two-dimensional arrays of circular jets of air impinging on a heat transfer surface parallel to the jet orifice plate are considered, and the air is constrained to exit in a single direction along the channel formed by the surface and the jet plate.
Abstract: Two-dimensional arrays of circular jets of air impinging on a heat transfer surface parallel to the jet orifice plate are considered. The air, after impingement, is constrained to exit in a single direction along the channel formed by the surface and the jet plate. The downstream jets are subjected to a crossflow originating from the upstream jets. Experimental and theoretical results obtained for streamwise distributions of jet and crossflow velocities are presented and compared. Measured Nusselt numbers resolved to one streamwise hole spacing are correlated with individual spanwise row jet Reynolds numbers and crossflow-to-jet velocity ratios. Correlations are presented for both inline and staggered hole patterns including effects of geometric parameters: streamwise hole spacing, spanwise hole spacing, and channel height, normalized by hole diameter. The physical mechanisms influencing heat transfer coefficients as a function of flow distribution and geometric parameters are also discussed.
314 citations
175 citations
TL;DR: In this article, the authors measured the heat transfer characteristics of two-dimensional arrays of jets impinging on a surface parallel to the jet orifice plate, where the impinging flow was constrained to exit in a single direction along the channel formed by the jet plate and the heat-transfer surface.
Abstract: Heat transfer characteristics were measured for two dimensional arrays of jets impinging on a surface parallel to the jet orifice plate. The impinging flow was constrained to exit in a single direction along the channel formed by the jet plate and the heat transfer surface. Both mean Nusselt numbers and streamwise Nusselt number profiles are presented as a function of Reynolds number and geometric parameters. These are the streamwise and transverse hole spacings ranging from 5 to 10 and 4 to 8 jet orifice diameters, respectively; the channel height ranging from 1 to 6 diameters; and the hole pattern which includes both inline and staggered arrays. The results show that significant periodic variations occur in the streamwise Nusselt number profiles, persisting downstream for at least ten rows of jet holes. Channel height can have a significant effect on the chordwise profiles, smoothed across the periodic variations. For the smaller channel heights, Nusselt numbers first decrease and then increase downstream. Where significant differences exist, inline hole patterns provide better heat transfer than staggered ones. These and other effects of the geometric parameters are presented and discussed.
148 citations
TL;DR: In this paper, the authors measured heat transfer characteristics for inline and staggered arrays of circular jets impinging on a surface parallel to the jet orifice plate, where the impinging flow was constrained to exit in a single direction along the channel formed by the jet plate and the heat transfer surface.
Abstract: Heat transfer characteristics were measured for inline and staggered arrays of circular jets impinging on a surface parallel to the jet orifice plate. The impinging flow was constrained to exit in a single direction along the channel formed by the jet plate and the heat transfer surface. In this configuration the air discharged from upstream transverse rows of jet holes imposes a crossflow of increasing magnitude on the succeeding downstream jet rows. Streamwise heat transfer coefficient profiles were determined for a streamwise resolution of one-third the streamwise hole spacing, utilizing a specially constructed test surface.
147 citations
TL;DR: In this paper, two-dimensional arrays of circular air jets impinging on a heat transfer surface parallel to the jet orifice plate are considered, where the jet flow after impingement is constrained to exit in a single direction along the channel formed by the jet and heat transfer surfaces.
Abstract: Two-dimensional arrays of circular air jets impinging on a heat transfer surface parallel to the jet orifice plate are considered The jet flow, after impingement, is constrained to exit in a single direction along the channel formed by the jet orifice plate and the heat transfer surface In addition to the crossflow which originates from the jets following impingement, an initial crossflow is present which approaches the array through an upstream extension of the channel The temperature of the initial crossflow air may differ from the jet air temperature The configurations considered are intended to model the impingement cooled midchord region of gas turbine airfoils in cases where an initial crossflow is also present Nusselt numbers and dimensionless adiabatic wall temperatures resolved to one streamwise jet hole spacing were experimentally determined for ratios of the initial crossflow rate to the total jet flow rate ranging from zero to unity These are presented and discussed relative to the flow and geometric parameters
109 citations
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TL;DR: In this paper, heat transfer characteristics of single and multiple isothermal turbulent air and flame jets impinging on surfaces are reviewed, and the effect of crossflow on impingement heat transfer is included.
935 citations
TL;DR: In this article, a review of recent impinging jet research publications identified a series of engineering research tasks that are important for improving the design and resulting performance of impinging jets: (1) clearly resolve the physical mechanisms by which multiple peaks occur in the transfer coefficient profiles, and clarify which mechanism(s) dominate in various geometries and Reynolds number regimes.
Abstract: Publisher Summary This chapter presents a discussion on jet impingement heat transfer. The chapter describes the applications and physics of the flow and heat transfer phenomena, available empirical correlations and values they predict, and numerical simulation techniques and results of impinging jet devices for heat transfer. The relative strengths and drawbacks of the Reynolds stress model, algebraic stress models, shear stress transport, and v 2 f turbulence models for impinging jet flow and heat transfer are compared in the chapter. The chapter provides select model equations as well as quantitative assessments of model errors and judgments of model suitability. The review of recent impinging jet research publications identified a series of engineering research tasks that are important for improving the design and resulting performance of impinging jets: (1) clearly resolve the physical mechanisms by which multiple peaks occur in the transfer coefficient profiles, and clarify which mechanism(s) dominate in various geometries and Reynolds number regimes, (2) develop a turbulence model, and associated wall treatment if necessary, that reliably and efficiently provides time-averaged transfer coefficients, (3) develop alternate nozzle and installation geometries that provide higher efficiency, meaning improved Nu profiles at either a set flow or set blower power, and (4) further explore the effects of jet interference in jet array geometries, both experimentally and numerically. This includes improved design of exit pathways for spent flow in array installations.
693 citations
TL;DR: In this paper, the authors present an overview of various cooling methods that can be employed for photovoltaic cells, including linear concentrators, single-cell arrangements, and densely packed photovolastic cells.
678 citations
TL;DR: In this article, the authors summarized the available analytical and experimental work in the area with the objective of correlating the research findings and suggested that there is considerable need for further research in liquid jet array applications, both in submerged and free-surface jet configurations.
Abstract: Publisher Summary Impinging liquid jets have been demonstrated to be an effective means of providing high heat or mass transfer rates in industrial transport processes. This chapter summarizes the available analytical and experimental work in the area with the objective of correlating the research findings. Significant progress has been made in understanding the fundamentals of heat, mass, and momentum transport in these systems. This chapter suggests that, there is considerable need for further research in liquid jet array applications, both in submerged and free-surface jet configurations. Cross-flow effects in these systems, which have been quite well characterized for submerged jets, have received only superficial treatment for free-surface jets. The physical phenomena are highly complex, requiring careful experimental investigation.
415 citations
TL;DR: In this paper, the relative strengths and drawbacks of the κ-e, κ −ω, Reynolds stress model, algebraic stress models, shear stress transport, and ν 2f turbulence models for impinging jet flow and heat transfer are compared.
Abstract: Uses of impinging jet devices for heat transfer are described, with a focus on cooling applications within turbine systems. Numerical simulation techniques and results are described, and the relative strengths and drawbacks of the κ-e, κ-ω, Reynolds stress model, algebraic stress models, shear stress transport, and ν2f turbulence models for impinging jet flow and heat transfer are compared.
260 citations