Heat Transfer and Fluid Flow Characteristics of Two-phase Jet Impingement at Low Nozzle-to-plate Spacing


Book Description

This study expands upon the current knowledge of the relationship between the heat transfer and fluid flow characteristics of air-assisted water impingement jets. Fluid flow and heat transfer characteristics of air-assisted water jet impingement were experimentally investigated under a fixed water flow rate condition with varying relative height (H/d). The test fluids were water and air. The effects of nozzle-to-plate spacing at volumetric qualities [beta]=0.3, 0.5, 0.7, and 0.8 where [beta] is the ratio of the volume of air to the total volume of the two-phase mixture on the hydraulic jump diameter, stagnation pressure, and stagnation Nusselt number were considered. The results showed that stagnation Nusselt number, hydraulic jump diameter, and stagnation pressure increased as the relative height decreased and the volumetric quality increased with the maximum values occurring at H/d of 0.02 and a volumetric quality of 0.8. This research is most applicable in the use of cooling of industrial applications such as cooling of electronics and processing of materials.




Comparison of Heat Transfer and Fluid Flow Characteristics Between Submerged and Free Surface Jet Impingement for Two-phase Flow


Book Description

Impinging jets have been studied in great depth due to their high rates of heat transfer and wide range of application. Some applications of impinging jets include electronic equipment cooling, metal annealing, furnace heating, and many others. The goal of this research was to understand the effects of the nozzle-to-plate spacing and volumetric quality on the Nusselt number of two-phase, free surface impinging jets and submerged impinging jets. The Nusselt number of two-phase, free surface and submerged impinging jets were obtained at several nozzle-to-plate spacings and the trends of the stagnation pressure and Nusselt number were compared. The Nusselt number of the submerged jet was also compared to that of the free surface jets with the same conditions. The two working fluids of the jet were water and air. The nozzle-to-plate spacing ranged from H/d = 0.03 - 8.5 and the experiment was done at five volumetric qualities. The Nusselt number and stagnation pressure decreased exponentially in both free surface and submerged jets for all volumetric qualities in Region I, the jet deflection region. In Region II, the transition region, the Nusselt number and stagnation pressure of the free surface jet remained constant with some fluctuation. The Nusselt number and stagnation pressure of the submerged jet continued to decrease linearly. In Region III, the free jet region, the Nusselt number and stagnation pressure increased linearly in the free surface jet and decreased linearly in the submerged jet. Comparing the values of the free surface and submerged jet, the submerged jet had a higher Nusselt number for low nozzle-to-plate spacings, and a lower Nusselt number for higher nozzle-to-plate spacings.




Survey of Literature on Flow Characteristics of a Single Turbulent Jet Impinging on a Flat Plate


Book Description

Flow characteristics of single jets impinging on flat surfaces have been studied by many investigators. The results of some of the numerous studies are summarized herein. Suggested methods for determining velocities and pressures on which to base heat-transfer correlations for use in impingement cooling design are presented.




Advances in Heat Transfer


Book Description

Advances in Heat Transfer, Volume 50, provides in-depth review articles from a broader scope than in traditional journals or texts, with this comprehensive release covering chapters on Heat Transfer in Rotating Channels, Advances in Liquid Metal Science and Technology in Chip Cooling and Thermal Management, Heat Transfer in Rotating Cooling Channel, Anomalous Heat Transfer: Examples, Fundamentals, and Fractional Calculus Models, and much more. - Fills the information gap between regularly scheduled journals and university-level textbooks by providing in-depth review articles over a broader scope than in traditional journals or texts - Essential reading for all mechanical, chemical and industrial engineers working in the field of heat transfer, or in graduate schools or industry




An Experimental Study of Volumetric Quality on Fluid Flow and Heat Transfer Characteristics for Two Phase Impinging Jets


Book Description

This study further expands the current knowledge of the relationship between heat transfer and fluid mechanics. Fluid flow and heat transfer characteristics of air-assisted water jet impingement was experimentally investigated under a fixed water flow rate condition. Water and air were the test fluids. The effects of volumetric quality (ß = 0 – 0.9) on the Nusselt number, hydraulic jump diameter, and pressure were considered. The results showed that stagnation Nusselt number, hydraulic jump diameter, and stagnation pressure increased with volumetric quality to a maximum value at 0.8 of the volumetric quality, and then decreased. The stagnation Nusselt number and hydraulic jump diameter of the air assisted water jet impingement are governed by the stagnation pressure. Based on the experimental results, a new correlation for the normalized stagnation Nusselt number and hydraulic jump are developed as a function of the normalized stagnation pressure alone. This research can be applied to further enhance the cooling of industrial applications, such as, cooling of electronics and processing of materials.













Three-Dimensional Attached Viscous Flow


Book Description

Viscous flow is treated usually in the frame of boundary-layer theory and as two-dimensional flow. Books on boundary layers give at most the describing equations for three-dimensional boundary layers, and solutions often only for some special cases. This book provides basic principles and theoretical foundations regarding three-dimensional attached viscous flow. Emphasis is put on general three-dimensional attached viscous flows and not on three-dimensional boundary layers. This wider scope is necessary in view of the theoretical and practical problems to be mastered in practice. The topics are weak, strong, and global interaction, the locality principle, properties of three-dimensional viscous flow, thermal surface effects, characteristic properties, wall compatibility conditions, connections between inviscid and viscous flow, flow topology, quasi-one- and two-dimensional flows, laminar-turbulent transition and turbulence. Though the primary flight speed range is that of civil air transport vehicles, flows past other flying vehicles up to hypersonic speeds are also considered. Emphasis is put on general three-dimensional attached viscous flows and not on three-dimensional boundary layers, as this wider scope is necessary in view of the theoretical and practical problems that have to be overcome in practice. The specific topics covered include weak, strong, and global interaction; the locality principle; properties of three-dimensional viscous flows; thermal surface effects; characteristic properties; wall compatibility conditions; connections between inviscid and viscous flows; flow topology; quasi-one- and two-dimensional flows; laminar-turbulent transition; and turbulence. Detailed discussions of examples illustrate these topics and the relevant phenomena encountered in three-dimensional viscous flows. The full governing equations, reference-temperature relations for qualitative considerations and estimations of flow properties, and coordinates for fuselages and wings are also provided. Sample problems with solutions allow readers to test their understanding.