Heat transfer from a pulsed laminar impinging jet request pdf. The combined device consisted of triangular tabs and a synthetic jet array that provided periodic disturbance to the jets shear layer. The fluid flow and heat transfer characteristics of an impinging jet with a combined activepassive device were investigated. Heat transfer enhancement in the oscillating turbulent. They have all the advantages and most of the disadvantages of conventional valved pulsejets, but without the reed valves that need frequent replacement a valveless pulsejet can operate for its entire useful life with practically. Enhancing heat transfer in internal combustion engine by. Pdf studies on pulse jet impingement heat transfer. The object of the project is to improve heat transfer predictions in combustion egines. Heat transfer from impinging jets is difficult to calculate with traditional methods k. Optimizing the benefits of pulse combustion impingement. Jet impingement has been used extensively in such processes, and the subject has been studied in depth over several decades e. Experimental data for the rate of heat transfer from impinging turbulent jets with nozzle exit. The analysis was studied under steady state and then compared with jets of different frequencies.
Heat transfer characteristic of an impingement cooling. A new method for convective heat transfer enhancement is described. Combustion is ubiquitous in traditional energy conversion systems such as automotive engines, stationary and aircraft gas turbines, rocket and space propulsion, electrical power generation, industrial furnaces, and home and institutional space heating. Heat transfer characteristics within an array of impinging. Heat transfer characteristics within an array of impinging jets effects of crossflow temperature relative to jet temperature l. The axisymmetric system of rans equations that take into account the twophase nature of the flow is resolved based on the euler approach. Pulse combustion devices offer several potential advantages over conventional burners, including enhanced efficiency, reduced size, automatic rejection of exhaust gases and consistency of operation over long time periods. Experimental and numerical investigation of heat and mass transfer due to pulse combustor jet impingement a dissertation presented to the academic faculty by michael j. Most studies have involved jets of the same temperature as the ambient fluid. The effect of injection parameters, such as injection distance, jettojet spacing and number of jets, on jet array impingement heat transfer is clarified. Heat transfer coefficient distribution at the surface is computed from the measured heat flux and temperature data using a reference method and a slope method.
Heat and mass transfer conference january 46, 2006 paper no. However, although there is a substantial number of mechanisms proposed, modeling works related to their enhanced thermal conductivity, systematic mechanisms, or models that are suitable for nanofluids are still lacked. Heat transfer in a pulse combustion water heater by. Forced convection heat transfer enhancement using a self. Many industrial processes involve mass or heat transfer to or from a material being manufactured or processed. Convective heat transfer in impinging gas jet arrangements j. Mar 24, 2016 the numerical modeling of heat transfer in a bubbly impinging jet is carried out. The actual heat transfer enhancement factors for this spacing were less than those for the smaller spacing, with a peak enhancement factor of approximately 60% for the highest flow rate case. Iit guwahati, india heat transfer by impingement of circular freesurface liquid jets john h.
This is due to the fact, that the impinged jet provides higher rate of heat and mass transfer. This site provides information pertinent to the benchmark problem entitled confined and submerged liquid jet impingement, set for the ichmt symposium cht01 advances in computational heat transfer to be held in palm cove, cairns, queensland, australia, 2025 may, 2001. The combustor is helmholtz type which has single combustor chamber and single tailpipe. Sibulkin derived a semianalytical relation for the laminar heat transfer of an impinging. Computation of heat transfer from an impinging flame jet to a. The current heat transfer enhancement levels achieved suggest that it may be possible to implement the present selfoscillating impinging jet concept in future gas turbine cooling systems, on rotating disks, glass temperingquenching, electronic equipment cooling, aircraft deicing.
Convective heat transfer in impinging gas jet arrangements. Electronic cooling using synthetic jet impingement journal of. Please use the links below to find more references relevant to this work, properties for. On the numerical modelling of impinging jets heat transfer. The combustion is modeled using a 12species probability density function method for the. Combustion science and technology 1993, 94 16, 147165.
Pulsed air jet impingement heat transfer sciencedirect. The pulse jet shows the higher heat transfer rate than steady jet at different frequencies. At high l0h, the stagnation heat transfer becomes independent of stroke length and can be approximated by nu0 1. His research topics include compact heat exchangers, enhancement of heat transfer, gas turbine heat transfer, combustion related heat transfer including thermal radiation, cfdmethods for laminar and turbulent fluid flow and heat transfer, liquid crystal thermography, condensation and evaporation, nanofluids, transport phenomena in fuel cells. The influence of different geometries of the nozzles of an impingement cooling. Heat transfer characteristic of an impingement cooling system. The average heat transfer coefficient increases for the frequency range of. Measures of performance include the specific impulse j sp thrusttoworking substance flow rate ratio, r or the specific thrust r sp thrusttoair flow rate ratio in airjet engines, r a. The combustion process in pulse detonation engine is the most important phenomenon as it produces reliable and repeatable detonation waves.
Accurate prediction of heat tranfer will contribute to accurate computation of combustion and emissions co2, nox etc project we will use cfd and perform fluid flow of fuelair jets to study heat transfer and mixing in the impinging zone. Introduction impinging of liquid jet on a surface to remove heat from this surface is an effective method for high heat flux heat transfer. The jet stream can be continuous or discontinuous, gaseous or liquid, or in the form of ions, electrons, photons, etc. The influence of the nozzle diameter on impinging jet flow patterns see fig. With this data, newtons law of cooling was to determine the local coefficient of heat transfer. Effect of variable duty cycle flow pulsations on heat. Over 80% of the worlds energy production and use is based on the combustion of fossil fuels. The major parameters characterizing jet engines are a thermo and gas dynamic performance. Su arizona state university tempe, arizona prepared for lewis research center under grant nsg3075 ni\s\ national aeronautics and space administration scientific and technical. Heat transfer by impingement of circular freesurface. On the transient numerical modelling of impinging jets heat transfer abstract this work compares a number of cfd transient models of an impinging jet. Prediction of turbulent heat transfer in impinging jet. Forced convection heat transfer enhancement using a selfoscillating impinging planar jet impinging jets are widely used in the local enhancement of heat removed from internal passages of gas turbine blades. At low l0h, the stagnation heat transfer increases with l0.
Pulsating jet impingement heat transfer enhancement. Turbulent impinging jet heat transfer enhancement due to intermittent pulsation. This paper focuses on analyzing the behavior of an impinging ame jet, including buoyancy e ects, turbulence in uence, and convective and radiative heat transfer processes. Dual pulsating or steady slot jet cooling of a constant heat flux. Effect of the size of air bubbles on enhancement of heat. The collaborative research center sfb 1029 is focused on the overall efficiency enhancement of gas turbines. Secondary peak in the nusselt number distribution of impinging jet. The specific case considered is an impinging jet with zd 6 and re 23000. We used three different heat transfer enhancement processes. Such applications as drying of paper, cooling of photovoltaic cells, deicing of aircraft wings. The use of jet impingement as a high performance technique for local. The heat flux and position data were used to determine local. Jetimpingement heat transfer in gas turbine systems. Heat transfer by impingement of circular freesurface liquid jets.
Pulse combustionimpinging jet heattransfer enhancement, combust. Effect of nozzle spacing on heat transfer and fluid flow. The operating cycles of pde consist of fuelair mixture, combustion, blowdown, and purging. Impact of the tio2 nanosolution concentration on heat transfer. Jul 24, 2014 an effect of crossflow velocity on flow and heat transfer characteristics of impinging jet in the case of low jet toplate distance at h 2d was experimentally and numerically investigated.
Due to the high heat transfer rate it can produce, impinging jet is one of the most. We discussed the flow and heat transfer characteristics of notchedorifice jets in the previous section and demonstrated that placing notches on the edge of the orifice nozzle can reduce the flow resistance and increase the turbulent intensity. Abstract to study the enhancement and degradation mechanism of impinging twophase heat transfer, airwater twophase jet was applied on the cooling of copper surface of 30 mm in diameter. Silverwater nanofluids used in this paper, has been prepared by a one step method adopting an ultrasoundassisted membrane reaction.
Heat transfer under a pulsed slot turbulent impinging jet at large temperature differences by peng xu a, arun s. The heat transfer coefficient h has a nearly bell shaped radial distribution at the plate surface for hd. Convective heat transfer from a pulsating radial jet. Wall pressure measurement and oil flow visualization on the target surface are performed to understand the flow pattern of impinging jet and wall jet. On the other hand, impinging jet cooling, which is the focus of the present. Numerical study of laminar pulsed impinging jet on the metallic foam blocks. In the experiments, the air jet from orifice impingement on the wall of wind tunnel while a crossflow was simultaneously induced normal to the jet flow. Typically, a pulse combustor may operate at frequencies that vary from 20 to 200 hz. Effects of jet formation frequency and reynolds number at different nozzletosurface distances h. Impingement jet cooling in gas turbines developments in. Method and system for calculating mass and energy balance.
Computation of heat transfer from an impinging flame jet. Free jet turbulent structure and impingement heat transfer, j. Heat transfer by impingement of circular freesurface liquid jets john h. Turbulent impinging jet heat transfer enhancement due to. Heat transfer characterization in jet flames impinging on. An experimental investigation has been performed to study the effect of flow intermittency on convective heat transfer to a planar water jet impinging on a constant heat flux surface. Numerical modeling of impinging jet flows and heat transfer is employed widely for prediction, sensitivity analysis, and device design. A valveless pulsejet or pulse jet is the simplest known jet propulsion device. In this project temperature and heat flux data were recorded with the heat flux transducer and the pulse combustor tail pipe exit jet temperature was recorded using a thermocouple. Heat transfer enhancement of impinging jet by notched.
Arrays of stationary jets are usually impinged on surfaces. Review on recent advances in pulse detonation engines. This thesis presents findings from an experimental and numerical investigation into merits of pulse coolant flow as an improvement to impingement cooling. Some works show improvements in heat transfer by the factor of 2. Amy and sharareh 22 conducted an experimental study on the influence of a protruding pedestal on a single circular impinging air jet on heat transfer rate with different reynolds numbers, jet exit diameters and jet exittosurface distances. Heat transfer enhancement in the oscillating turbulent flow. Department of energy, office of industrial technologies, advanced industrial concepts division. The turbulence of the liquid phase is described by the reynolds stress transport model with taking into account the effect of bubbles on modification of the turbulence. Impinging turbulent round jet with heat transfer, a.
Steady impinging jets feature high local heattransfer coefficients. The results indicate that the silver nanoparticles can be uniformly distributed in the base. Largeeddy simulation of impinging jet heat transfer bin zhao. Largeeddy simulation of heat transfer in circular impinging jet bin zhao. Experimental heat transfer, fluid mechanics and thermodynamics. In order to obtain more uniformity in the heat transfer distribution, an array. Valveless pulsejets are low in cost, light weight, powerful and easy to operate. Maximizing applications and minimizing theory, it covers modes of heat transfer, computer modeling, heat transfer from flame impingement, from burners, low temperature.
T1 jet impingement heat transfer in gas turbine systems. The technique involves the use of a pulse combustor to generate a transient jet that impinges on a flat plate. Impinging jet heat transfer largeeddy simulation of. Woodruff school of mechanical engineering georgia institute of technology. Numerical simulation results, quantifying the effects of impingement zone geometry on pulse. Lienhard v department of mechanical engineering massachusetts institute of technology cambridge ma 0294307 usa email. Electronic cooling using synthetic jet impingement journal. The pulsed impinging jet performs better in the wall jet region at hw 3 and 5, while, heat transfer enhancement can be found in both of stagnation and wall jet regions at hw 8. Experimental study on the alteration of cooling effectivity through. These include reynolds numbers, re, from 0 to 30000, nozzle to impingement. Heat transfer characteristic of an impingement cooling system with different nozzle geometry k marzec1 and a kucabapietal2 1 rzeszow university of technology, mtu aero engines, rzeszow, poland 2 rzeszow university of technology, rzeszow, poland email. Examples of industrial applications of impingement heat transfer are annealing of metals, tempering.
Experimental investigations on heat transfer of submerged jet in plate and pinfin heat sinks were carried out with different concentrations of silver nanofluids. Heat transfer from an inert jet to a plate has been studied extensively in the past 2023. Convective heat transfer to an impinging air jet is known to yield high local and area averaged heat transfer coecients. Cfd simulation, heat transfer enhancement, impingement heat transfer, pulsating jet, pulse combustion, vortex structure. Effect of crossflow velocity on flow and heat transfer. Jet impingement, forced convective heat transfer, heat transfer enhancement, nanofluids, nanoparticles, aluminawater nanofluid. Electronic cooling using synthetic jet impingement. Heat transfer experimental internal cooling dynamic impingement cooling crossflow pulsed blowing. Convective heat transfer enhancement due to intermittency. Heat transfer enhancement by using nanofluid jet impingement. A series of simulations were conducted at re12k and 30k for frequencies up to 20hz and amplitude ratios up to 70% of mean mass flow and standoff and nozzle spacing equal to three diameters.
This project was conducted in order to acquire an understanding of the heat transfer characteristics and pressure oscillations occurring in pulse combustion devices. Heat transfer in a pulse combustion water heater by hsin. Heat transfer enhancement nearly by a factor of 2 due to pulsed impinging jets was. Effect of injection parameters on jet array impingement. Nanofluids exhibit novel properties including significant heat transfer properties that make them potentially useful in internal combustion engine cooling. The detonation wave initiation in detonation tube in. Finite element, finite difference, and finite volume computational fluid dynamics cfd models of impinging jets have succeeded in making rough predictions of heat transfer coefficients and velocity fields. Convective heat transfer enhancement due to intermittency in. Mujumdar b, hee joo poh c, and boming yu d a in sti tute of sur face phys ics, col lege of sci ence, china jiliang uni ver sity, hangzhou, p. Psimas in partial fulfillment of the requirements for the degree doctor of philosophy in the george w.
The current research is concerned with the measurement of heat transfer to an impinging air jet over a wide range of test parameters. Tio2 nanoparticles, nano coating, impingement jet, heat transfer. A jet engine is an aircraft engine used to provide p ropulsion for a vehicle by ejecting a substance flow, i. Heat transfer enhancement in the oscillating turbulent flow of a pulse combustor tail pipe john e. Heat transfer and fluid flow characteristics of impinging.
Enhancements in convective heat transfer of a factor of up to 2. The efficiency and mechanisms of cooling a constant heat flux surface by impinging synthetic jets were investigated experimentally and compared to cooling with continuous jets. Enhanced heat transfer was achieved by periodically restarting an impinging flow and thereby forcing renewal of the hydrodynamic and thermal boundary layers. Effects of various flow and geometric parameters on the flow, heat mass transfer in the impingement and wall jet zones of singlemultiple, roundslot jets impinging normallyobliquely on a stationarymoving surface which may be permeable or impermeable are discussed. Heat transfer performance of submerged impinging jet using. Heat transfer enhancement of impinging jet from pulse jet. A pulse combustion powered apparatus for heating and pressurizing fluids, comprising in combination a pulse combustion heat engine, compressor means, and primary heat exchange means for transferring heat rejected by the heat engine to a primary fluid to be heated, said heat engine including chamber means for pulse combustion of a fuel to provide combustion gases. An extensive discussion of swirl flows is documented in the book by.
Introduction the impinging jet can be described as a phenomena in which the fluid exiting from a nozzle or orifice. Heat transfer from a flat surface to an oblique impinging jet was studied by goldstein and franchett 1988 and foss 1979. Kotake and hijikuta, numerical simulations of heat transfer and fluid flow on personal computer, elsevier science publishers, 1993, tj 260. The aims of this study are to investigate flow characteristics in pulse jet combustor and heat transfer characteristics of impinging jet from pulse jet combustor. The inner diameter d of tailpipe was 47 mm and tailpipe length was about 16d. The average heat transfer coefficient increases for the frequency range of 5hz to 50 hz. Combustion and heat transfer usc viterbi department of. Pulse detonation engines pdes are new exciting propulsion technologies for future propulsion applications. Analysis of the heat transfer of an impinging laminar. At h w 3, an obvious drop of the timeaveraged local nusselt number distribution can be found in the wall jet region, which can be ascribed to the reflected. Prediction of turbulent heat transfer in impinging jet geometries.
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