In this study we succeeded in the decrease of the noise of the centrifugal fan which is used for a indoor unit of air-conditioners by designing a new blade. The flow structure of the centrifugal fan was analyzed by the numerical calculation. The huge separation flow in case of existing blade is formed near hub side. Otherwise the separation from the suction surface of the new blade is suppressed and the loss of total pressure is decreased because of the increase of the chord-wise velocity. It is considered that there are strongly correlation between the noise and the loss of total pressure.

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In recent years, with the rise of interest in environmental problems, noise reduction in motors has become a strigent requirement There are three kinds of motor acoustic noise: ventilation noise, electromagnetic noise and machine noise. It is assumed that ventilation noise in high speed machines consists mostly of fan noise. Fan noise, depends on the number of rotations and the number of fan blades and by the turbulence sound produced by the disturbed flow of cooling air. Many studies have been done on reduction of fan blade and turbulence noise by flow analysis based on fan blade number and shape. However, there have been no papers describing the space resonance frequency of the fan space, which is a propagation channel of the fan noise. Thus, in this paper, the space resonance frequency and resonance mode of the fan channel analyzed by Helmholts theory and experiments. The effect of rotational sound and resonance mode on noise is also described.

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The final purpose of this study is to clarify the relation between the static pressure fluctuation between fan blades and the sound noise emitted to the outside of the fan. For this purpose, first of all, a new micro probe for the measurement of the static pressure fluctuation has been developed. The measurement of the static pressure fluctuation between the blades has been performed, and the intensity of sound source was quantified from the second derivative of phase averaged static pressure fluctuation signal (Ribner 1962). It is shown that the intensity of sound source becomes largest when the blade approaches to the nose. The difference between the cooling mode and the heating mode are also investigated. It is found that the sound source for cooling mode shows the larger value than that for heating as a whole.

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As for propeller fan, the internal flow structure and the noise characteristic are known to be different according to operation point. However, the relation between them is not so clear. In this paper, measurement of the downstream of propeller fan by hot-wire probe and the pressure fluctuation of the casing wall was carried out, and the following results were obtained. The higher the flow ratio is, the closer the tip vortex reaches the downstream to the blade that discharges it. As for magnitude of velocity fluctuation, pressure fluctuation of the casing wall and noise level, the tendency to the flow ratio is different respectively.

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In the previous study, it was clarified in the right-angle branch with single side branch that the velocity periodically oscillates in the side branch, and the Strouhal number is independent of cross-sectional area ratio, the flow division ratio of main branch to side branch, and the Reynolds number. In the present study, the flow structure in the right angle branch with double side branch has been experimentally studied in laminar steady flow using laser Doppler anemometer and particle image velocimetry. Consequently, the velocity periodically also oscillates in both side branches, and the Strouhal number is independent of the Reynolds number although the Strouhal number in the downstream side branch is a little larger than that in the upstream side branch. It has been clarified that the flow oscillation in the right-angle branch is a characteristic phenomenon caused from the geometry of right-angle branch and the factor inducing oscillation would be high shear rate.

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Free vibration tests of a sphere tethered in a vertical water tunnel were conducted up to critical Reynolds number (3×10^5). The reduced velocity in the tests was in the range of 2〜36. Dynamic behaviors of a sphere were taken by a digital video camera. The drag force on the sphere was also measured. The sphere vibrates above a critical flow velocity, and circular or elliptical trajectories in the plane perpendicular to the flow direction can be observed. The relative amplitude increases as the flow velocity increases, and the sphere finally hits on the side wall of the water tunnel around the critical Reynolds number, i.e., the maximum amplitude of the vibration is beyond 2 times the sphere diameter.

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In previous investigations, a series of wind tunnel tests was conducted on the vibration and scattering behavior of full-sized model of roof tiles, which were used widely for roofings of Japanese wooden dwellings. As a result, the mechanism of vibration and scattering of roof tiles could be understood. This paper describes a water leak test of roof tiles. The 100 roof tiles were set up on 10 lines and 10 rows on the pitched roof in the downstream of the flow from the wind tunnel. The experimental apparatus for the purpose of reproducing the wind and the rain was used. The situation of the water leak test was filmed by video camera. The water leak phenomena in the experiment by using the artificial rain fall apparatus are discussed in this paper.

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This paper deals with self-excited vibration of an overflow pipe due to fluid discharge. The vibration characteristics, instability mechanism and regions of the self-excited vibrations generated in the overflow pipe, which have an elbow at the tip of the pipe, are examined by theoretical analysis and experiments. In the theoretical analysis, a theoretical model of the self-excited vibration in vertical direction is developed, and instability regions and conditions are examined by the stability analysis. In the experiments, instability regions and boundaries, at which the self-excited vibration occurs, are examined by alternating the fall height (vertical pipe length), horizontal pipe length, and the flow rate. The theoretical results are in good agreement with experimental ones about the instability regions.

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A new type of damper called "flexible liquid damper" is being developed. This damper is composed of a flexible ball partially filled with liquid. The important feature of this damper is the surface of the ball moves with the motion of the attached structure followed by the motion of the fluid inside the ball. This fluid-motion gives much energy dissipating effect, which results to a big damping ratio. In this paper, the basic trend of the damper is introduced by shaking tests, both by a pricking and by a shaker test. To compare with the dynamic damper, an analytical explanation is tried, but it is not enough to express the damping value of this damper only with the mechanism of the dynamic damper. It is supposed to have another effect by the fluid motion.

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Regarding the air entrainment into a suction pipe which is vertically inserted into a suction sump across a free surface, critical submergence S_c are specified concerning six parameters, such as the Froude number Fr, the Reynolds number Re, the Weber number We, back clearance X, sump breadth B and bottom clearance Z. Here, all parameters are non-dimensionalized by suction-pipe outer diameter D and suction-pipe intake velocity V_i. Consequently, the authors confirmed that the surface-tension effect is negligible at We≥20, and that the viscous effect become enough small at Re≥3.2×10^4, while Fr effect is significant. Z/D effect also becomes small at Z/D≥2.5. Most of geometric effects can be explained on the basis of the Fr-S_c/D relation.

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This paper deals with an active feedback control of sloshing in a transport container by a moving plate. The sloshing is effectively suppressed by the energy dissipation caused by vortexes generated around the edge of the bulkhead. In this paper, an active control device using a moving plate driven by a DC motor is developed, and the suppression effect by the moving plate on residual sloshing excited by sudden stop of the transport container is examined experimentally. The control performance is clarified by changing the controller gain and phase shift. It is found that sloshing is more effectively suppressed with control in opposite phase shift.

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The present paper is concerned with a numerical simulation and an experimental evaluation of transition of flow around a two-dimensional airfoil. An LES (Large-eddy simulation) with classical Smagorinsky model is conducted with SMART-fem code to simulate the wind tunnel experiment for a wind-turbine airfoil, M-F073. The numerical results show that the flow is massively separated from the airfoil surface at Re=2×10^4, while it is almost attached at Re=2×10^5. The transition features turn out qualitatively consistent with the experimental results in terms of the lift coefficients and pressure distribution, though the transition Re of the computation is lower than that of the experiment, mainly due to lack of enough resolution.

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Noise generated aerodynamically increases drastically with increase in the rotational speed of turbomachinery. In fact, it increases with 5^<th> to 8^<th> power of the rotational speed. Prediction and reduction of turbomachinery noise is, therefore, of great engineering importance. In this paper, present status of the numerical prediction of turbomachinery noise is reviewed. Based on this review and outlook for the computational fluid dynamics in general, future trend of numerical prediction of turbomachinery noise will also be discussed.

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Wet-steam flows through 2-D and 3-D multiple-stage turbine cascades are numerically investigated. Fundamental equations contain conservation laws of water vapor, water liquid, the number density of nucleus, momentum equations, and the energy equation. The SST turbulence model is employed to predict the eddy viscosity. The classical condensation theory is used for modeling homogeneous and heterogeneous condensations. These equations are solved by the fourth-order compact MUSCL TVD scheme and LU-SGS scheme. A parallelized LU-SGS method based on the pipelining method is newly employed for the parallel-implicit time-integration. As numerical examples, 2-D and 3-D flows of wet steam through two-stage stator-rotor cascade channels in a steam turbine are computed.

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The tip clearance of rotor blades is one of the important factors to be more investigated, because the rotating stall inception originates at a tip leakage flow region in most of axial flow compressors. However, the effect of the tip clearance on unsteady flow field at near-stall condition has not been investigated in detail. In the present work, the unsteady flow phenomena in a low-speed axial flow compressor stage with the large and small tip clearances at near-stall condition have been investigated numerically by URANS (Unsteady Reynolds-averaged Navier-Stokes) simulations. The results show the clear difference caused by the effect of the tip clearance on the flow field at near-stall condition. Namely, the occurrence of separation at the blade suction surface induced instability for small tip clearance, while the occurrence of tip leakage vortex breakdown induced instability for large tip clearance.

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The purpose of this study is to better understand the unsteady behavior of tip leakage flow in rotating stall inception and to investigate the dominant mechanism of stall inception. A 3D URANS calculation was conducted to simulate the spike-type stall inception of a transonic axial compressor rotor (NASA Rotor 37). The simulation was run with a four-passage grid that could capture the rotating disturbance in the spike-type stall inception. The simulation demonstrates that the unsteadiness of tip leakage vortex, which has been caused by the vortex breakdown at near-stall condition, brings about the flow phenomenon similar to "spillage" and invokes the rotating disturbance in the stall inception.

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It is very unique and useful technique for Turbomachinery CFD unsteady analysis, which is called Non Linear Harmonic Method. It requires only one blade channel although this is unsteady analysis and it makes designer helps reducing CFD time consumption as keeping prediction accuracy. This paper describes the brief functionality for this technique and shows centrifugal and axial compressor applications.

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We predicted a cavitation erosion area in an open-type mixed-flow pump that was subject to tip vortex cavitation by using a numerical simulation code based on the `bubble flow model'. The erosion area on the impeller blade was predicted by estimating the cavitation intensity that was defined with the detailed bubble pressure and the bubble nuclei distribution. For comparison, we determined experimentally the erosion area in the same pump using a paint method. The predicted and the actual erosion areas located near the blade tip in the middle of the blade between the leading edge and the trailing edge. In the previous work, the code was used to predict the erosion area on the impeller blade of a closed-type centrifugal pump. The results from the previous work and this current work show that our code successfully predicts erosion areas in closed-type and open-type pumps.

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An optimization design of pump inducer by using three dimensional inverse design method, computational fluid dynamics (CFD) coupled with optimization technique was performed. Design of experiments technique and response surface methods were used to analyze design parameters such as loading distributions, meridional shape and number of blades to find out optimum values for suction performance. The analyzed suction performance of the inducers designed by optimum loading distributions showed better than that of original inverse designed inducer.

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In our previous study, a design tool based on computational fluid dynamics (CFD) and numerical optimization was developed. Commercial CFD software (STAR-CD) and a simulated annealing algorithm were used to maximize fan efficiency in the design tool. Fan efficiency of the optimized fan using the design tool was increased remarkably by experimentation. In this study, blade shapes and total pressure distribution of the initial and optimized fans are compared to investigate design scheme for high efficiency fan. This investigation shows that spanwise total pressure distribution of the optimized fan is uniform compared to that of the initial one. Therefore, uniform distribution of total pressure is an important factor in designing a high efficiency fan. A further finding is that convex spanwise distribution of the setting angle is the key factors in increasing fan efficiency and that convex spanwise distribution of solidity and the sweep angle are secondary factors.

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Optimization of blade loading of mixed-flow impeller was PRACTICABLY done by using the inverse design method. We obtained a couple of the results that contains the optimized impeller, the design charts and the flow mechanisms those improve performances such as efficiency and cavitation.

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A sensitivity analysis of mixed-flow impeller's design parameters was performed in the first stage of optimization design of mixed-flow pumps that have a performance trade-off. High efficiency, non-stall, and low shut-off power were set as objective functions. This study was done by combining the three-dimensional inverse design method and CFD, some design parameters of impeller were founded to have trade-off problem for performance.

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For modern aeroengines, it has become one of the important design issues to reduce weight as well as any kind of cost, while maintaining their high thermal efficiency. In this paper, we aim to trim weight of HP turbine blade while keeping enough space for cooling structure. We have searched for the optimum blade shapes that are much lighter than the original blade with similar aerodynamic performance by using Lattice Boltzmann Method as method for analyzing and Multi Objective Genetic Algorithm as optimization technique.

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To reduce aerodynamic sound, investigation of the sound generation mechanism in flow field is very important. The detailed investigation of the sound source requires velocity measurements with high temporal and spatial resolution and the development of sound source exploration. In this study, sound source in the turbulent mixing layer have been investigated by the time-resolved stereoscopic particle image velocimetry (TRSPIV). Powell's sound source and Reynolds stress component of the Lighthill sound source have been evaluated from the experimental results and compared with those of direct numerical simulation.

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To investigate the hierarchical structure of turbulent wall shear flows, direct numerical simulation of turbulent channel flow has been conducted for Re_τ=1270. The central axes of coherent fine scale eddies (CFSEs) are identified, and spatial distributions of the axes of the CFSEs and characteristics of the flow field are visualized by using a new method. The low-speed regions in the logarithmic law region are composed of many CFSEs or the cluster of the CFSEs with relatively strong swirling motions. The scale growth of clusters of CFSEs with a distance from the wall is deeply related with the scale growth of the low-speed regions in the logarithmic law region. The cluster of the CFSEs is closely related to turbulence production in the logarithmic regions

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We propose a new numerical method extended from the usual incompressible scheme, taking into account the density variation to realize the turbulent heat transfer prediction accurately. For the assessment of the applicability of this method for the flow field where the compressibility is not negligible even in the case of low Mach number, the direct numerical simulations(DNS) of turbulent flow in a horizontal channel of different wall temperatures are carried out. Then the results for the turbulent flow under some conditions of unstable stratification are compared. The temperature profile was shifted in comparison with the result by Boussinesq approximation. Also, it was affected by the viscosity and thermal conductivity when temperature effect on them was considered.

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Granulation is generally performed in stirred vessel to spray binder into row material and to stir particles. However, the conventional granulating system has some problems. First, there are 2 peaks in the particle diameter distribution that may degrade the quality of products. Second, it takes too long time to determine the operating conditions for desired particle diameter distributions. Therefore, it is required for us to highly control granulation process in stirred vessel with computer simulations. In the present study, we perform numerical experiments of granulation process in stirred vessel to clarify the reason why 2 peaks in the particle diameter distribution appear.

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In heat exchanger, the thermal contact resistance is desirable to be as small as possible. But the method for measuring thermal contact resistance accurately is not established. Photoacousitc method is the one of non-contact and non-destructive method which can measure the thermal properties of various materials. We investigate the thermal contact resistance between Cu and Al by analyzing a phase lag of the photoacoustic signal to incident light, using flat and curved surface samples as used in practical heat exchanger.

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Laser-induced breakdown and the ignition were occurred by focusing a 532nm pulse from Q-switched Nd: YAG laser. Methane-air premixture at 1 atm was ignited in a constant volume chamber. In this study, we investigated how the temporal and spatial profile of laser pulse and characteristics of collecting lens have an effect on the breakdown thresholds and the minimum laser pulse energies (MPE) needed for ignition. This measurement result showed that excitation energy of flash lamp changes not only the laser energy but also the temporal and spatial profile of laser pulse. As excitation energy of flash lamp decreases, the laser pulse duration become longer and the spatial profile is getting closer to Gaussian distribution. As a result, MPE depend largely on the temporal and spatial profile of laser pulse. Specifically, as excitation energy of flash lamp decreased, MPE decreased.

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Since Cellular Automata (CA) have been proposed by von Neumann in the late 1940s, CA have been applied in a variety of scientific researches on complex system, including traffic models and biological fields. It is an idealization of a physical system in which space and time are all discrete. In this study, we have simulated evacuation dynamics in fire by Real-coded Cellular Automata (RCA), which we proposed as a new approach for pedestrian flow. To consider the fire spread in discrete space in calculation code, percolation model has been used.

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A two-dimensional numerical simulation is applied for spray flames formed in a laminar counterflow, and soot formation behavior is studied in detail. N-decane (C_<10>H_<22>) is used as a liquid fuel. A one-step global reaction is employed for the combustion reaction model. A kinetically based soot model with flamelet model is employed to predict soot formation. Radiation is taken into account using the discrete ordinate method. The results show that the soot is formed mainly in the spray diffusion flame region. The soot formation behavior is well demonstrated by the present soot formation model.

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In this study, we measured soot and NO_x in a cyclone-jet combustor. A laser induced incandescence (LII) technique was applied to obtain instantaneous soot concentration. As for NO_x emission, premixed and non-premixed combustion were examined with changing equivalence ratio. Results show that, when the air volume rate is increased, EINO_x in non-premixed combustion is reduced to the level of premixed combustion. The soot is not detected when the equivalence ratio is less than 2.

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In the present study, flow and flame characteristics of a jet array, which consists of three jets arranged in a row, were evaluated. Methane and air were supplied from the center and two side jets, respectively, each of which was pulsated periodically with the same flow rate. Schlieren photographs were taken by a high-speed digital video camera in combustion cases. Velocity distributions in non-combustion cases were obtained using a laser-Doppler velocimetry. More significant effect of the periodic flow rate change on the flow patterns was observed in the combustion cases than in the non-combustion cases.

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In this study, we used a small scale downdraft gasifier of char. The result shows that calorific value of produced gas per unit time is increased as air ratio is increased from 0.35 to 0.45. Calorific value of produced gas per unit time is far larger by above 40% when the air is supplied into the char bed than gaseous layer. In case the air is supplied into char bed. calorific value of produced gas per unit time is increased as temperature of air and the mass of water vapor supply is increased.

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In order for global environment problems to delay advance of solution or aggravation, consideration about suitable use of resource energy was performed on the basis of recognition that the correspondence to an energy problem is the most important. In particular, data focused on the construction material with which it is mostly equipped fully, and quantified about the value as resources. Consequently, the difference in the energy capacity factor in steel structure and a tree structure was able to be clarified. Moreover, the wood currently used for a building was regarded as recycled resources, and the distribution in all prefectures was shown.

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The vehicle powered by the solar energy is expected to be clean and to make energy savings. In this report, the solar thermal collecting system, which collects the solar energy from the sunlight as power source of the vehicle and uses Evacuated Double Glass Tubular Collectors with selection-absorption film, was tested to evaluate the characteristics of the collecting the solar energy. The test results present that the solar thermal collecting system needs to improve the construction and the efficiency and clarify the route of heat rejection from the tubes.

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In order to reduce energy consumption of air conditioning system, lowering setting temperatures and under dress in offices are recommended today in Japan. Although, feeling of comfort in this recommendation is not satisfactory indeed. In this paper, direct blowing inside clothes of human body is proposed to reduce the sense of heat in the condition of unsatisfied thermal environmental. Measurement of sensible heat flux and surface temperature of clothed thermal mannequin with blowing inside of cloths were conducted. Further more blowing rate inside cloths and thermal sensation were measured for human body. Reduction of sense of heat by direct blowing inside clothes of human body was confirmed and it is obtained that proposed system is effective to thin body rather than to fat body.

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The author's previous study proposed a new evaporation supply method for liquid precursors in a chemical vapor deposition (CVD) process called flashing spray CVD (FS-CVD). In this method, the liquid precursors are supplied directly to a vacuum chamber through an injector, just like fuel for an automotive engine. This unsteady and intermittent spray with flash boiling requires no vaporizer. Further, the authors developed a way to relatively reform the saturated vapor pressure of the precursor by mixing with a lower vapor pressure organic solvent for the effective use of this method. It is easier to obtain the active flashing spray due to the higher vapor pressure of mixed material. In this paper, to improve the vaporization of Tetraethylorthosilicate (TEOS) as the precursor, n-pentane is mixed as the higher vapor pressure material. The vapor formation of flashing spray for various mixing fractions of n-pentane was observed by the image analysis of LIF and Mie scattering. The result shows that it is possible to form suitable flashing spray of two-component solution by incorporating organic solvent on effective mixing fractions.

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In this study, we investigated the way to evaluate the amount of the adhesion fuel on the inclination wall when spray wall impingement occurred by considering the normal and the tangential impingement droplet velocity. As a result of comparing with experiment result, it was shown that the way we proposed could calculate the adhesion fuel behavior which the conventional way could not calculate.

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In this study, numerical simulation has been conducted for the spray injected from a slit nozzle injector for a direct gasoline engine. The droplets in the spray were investigated by the combination of Large Eddy Simulation (LES) and Lagrangian Discrete Droplet Model (DDM). Droplets are atomized through the primary breakup induced by the instability of the liquid surface and secondary breakup induced by relative velocity between droplet and surrounding gas. This paper applies three secondary breakup models to an injector spray flow and evaluates their results compared with experimental data.

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Effects of diesel fuel split-injection on fuel-air ratio and gas velocity distributions inside a combustion chamber are studied numerically using a modified code of KIVA. This study is intended to find optimum liquid fuel split-injection configuration. It is found that, among all schemes evaluated, the configuration where 75% of fuel mass is injected on the first injection and the remaining is injected 1.0ms after the end of the first injection is preferred as the optimum configuration that can contribute to particulate emission reduction. It is also found that dwell durations do not have a strong correlation with the flammable area formed due to the fuel injections and longer dwells delay the effect of the second injection on gas velocity profile and postpone the utilization of effective time for taking advantage from second injection.

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In this study, unburned hydrocarbon (HC) emissions of a Premixed Compression Ignition (PCI) engine were investigated by experiment and numerical simulation, and the reason of HC exhaust was clarified. According to the results of experiment; it was shown that a considerable amount of HC emission was exhausted during the advanced injection timing, and as the injection timing was delayed, HC emission increased with the injection timing temporarily, and then it decreased remarkably at the late injection timing, The reason of the HC emission characteristics was analyzed by simulation of mixture formation using a GTT code.

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The detailed behavior of gaseous and spray lifted flames are studied by two-dimensional direct numerical simulations (DNS), and the characteristics are investigated in terms of two key variables for flamelet modeling. The results show that both the gaseous and spray lifted flames are partially premixed flames, in which premixed and diffusion flames co-exist and the premixed flame stablizing the flames precedes to the diffusion flame. The premixed and diffusion flames in the partially premixed flame can be predicted by the flame index. Although the flamelets in the diffusion flame of the gaseous lifted flame are modeled by flamelet model, thoses on the spray lifted flame are not. To account for the flamelet characteristics of the spray lifted flame, the flamelet/progress-variable approach needs to be introduced.

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Effect of the droplet size distribution of fuel spray on the soot formation process in spray flames is investigated. The vibratory orifice atomizer is used to control the droplet size distribution of fuel spray. Two-dimensional soot volume fraction, primary soot particle size and relationship between spatial distribution of fuel droplets and soot formation area are observed by optical measurements. The results show that flame structures of spray flame and soot formation process are affected critically by the mean droplet size of fuel spray. The mean soot formation area is increased by increase of the mean droplet size of fuel spray. The primary soot particles become large at around the edge of soot formation area. This trend occurs from coagulation and surface growth of soot particles. The group of some droplets and its vapor forms the soot formation area, and the large droplet of liquid fuel deforms shape of the soot formation area.

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Combustion experiments of fuel droplet array were performed to investigate growth mechanism of group combustion of fuel droplets. The purpose of this research is to examine the effect of gas-phase equivalence ratio on the flame spread. Ten fuel droplets were simultaneously generated with very thin glass tubes and suspended in a straight line at the crossing points of X-shaped suspenders which were fixed at equal intervals. Fuel vapor-air mixture was filled in a combustion chamber. Behavior of flame spread along a fuel droplet array was observed and flame spread speed was measured for various droplet intervals and gas phase equivalence ratio. It was found that the flame spread speed increases with the increase in the gas-phase equivalence ratio. Flame spread speed increases up to droplet interval of 1.8mm and then decreases. In the case of 0.7 in the gas-phase equivalence ratio and 1.8mm in the droplet interval, a gas-phase propagating flame, which preceded a spreading flame along droplet array, appeared at the final stage of flame spread.

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The effect of injection rate modulation on the spatial dispersion of fuel droplets and inner structure of fuel spray were investigated by using an electronically controllable fuel injection system. The major experimental parameter was the modulation frequency and changed from 0Hz to 15kHz. From the experiments, it was confirmed that the shape of spray with injection rate modulation becomes wider at some frequencies, i.e., 5kHz, 7.5kHz and 13kHz in our experiments, and the reason of this phenomena was discussed briefly.

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Addressed in the present study is the required accuracy in assuming equivalent thermal conductivities of printed circuit boards (PCBs) in the thermal analysis of electronic equipment. Out of various PCB morphologies two are considered as representatives in the extreme ends of PCB size and thermal conditions; one is a JEDEC test board having a large convection-cooled area, and the other is a small board in contact with a large solid thermal mass. The major focus of the present paper is on the case of a JEDEC test board carrying a ball grid array package. In exploring modeling strategies the analyses were performed on three models having different geometric resolution levels. Comparison of the results on the three models proves that the accuracy of temperature prediction is in general insensitive to the equivalent thermal conductivity values due to the dominant role of surface heat transfer on the temperature level of PCB.

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