Non-uniform Heat Transfer Research Articles

Study on the uneven flow distribution and non-uniform heat transfer in microchannels

The power module is one of the main heating sources with non-uniform heat flux in high-power electrical servo systems used for flight vehicles. Faults in the power module are usually caused by a high or a non-uniform temperature. Given the environment of heat dissipation during flight, a regenerative cooling method is typically used, and the cooling system is designed as a microchannel heat sink with supercritical fuel. This is an effective means of solving thermal problems in the flight vehicles. However, because of the high heating power and non-uniform heat distribution of the power module, it is necessary to optimize its heat sink to restrict the high temperature rise and suppress the non-uniform distribution of temperature. In light of these considerations, a 3D numerical model of the microchannel heat sink of a power module with non-uniform heat flux was established in this study to examine the heat transfer and the thermal performance of the cooling channels. Based on the validation of the mesh and numerical method, the simulations of the flow distributions of the channels were performed to assess the thermal performance of the heat sink. It included investigating the effects of the inlet location of the manifold and its injection angle on the flow distribution in the channels, and the influences of the flow distribution and the operational parameters on the thermal performance of the heat sink. The results revealed that the Z30 configuration provided the best location and injection angle of the inlet to match the non-uniform heat flux of the power module. In this case, the values of Stanton number and buoyancy parameter of channel 4 yielded the minimum values of all channels owing to its higher flow rate and gradual rise in temperature. The deviation in the rate of mass flow Φ changed slightly corresponding to the various operational parameters, only the total heat flux would bring a bigger fluctuation. The tiny difference in temperatures among the observation areas on the substrate verified the positive influence of the flow distribution in matching the non-uniform heat flux.

Some recent progress in reactor core thermal-hydraulics modelling

In the last more than ten years the research groups of the present authors have been working on some of the key phenomena or parameters widely used in sub-channel thermal-hydraulics (SCTH) codes, e.g. (a) transversal exchange between sub-channels, (b) circumferential non-uniform heat transfer in fuel assemblies with tight or semi-tight lattice (pitch-to-diameter ratio smaller than 1.25), (c) PDO heat transfer and rewetting and (d) CFD analysis of two-phase flow and heat transfer, incl. critical heat flux. Among others, three transversal exchange phenomena were studied, i.e. turbulent mixing coefficients, void drift and wire wrap induced sweeping flow. New models for various turbulent mixings, void drift and wire wrap induced cross flow were developed based on analytical analysis and CFD simulations. Importance of the non-uniform heat transfer behavior inside single sub-channel was identified in fuel assemblies with tight or semi-tight lattice. Correlations for predicting the non-uniform heat transfer coefficient were proposed, which were implemented into SCTH codes, to accurately determine the local hot spot on the fuel pin surface. A large experimental data base containing more than 60,000 data points of PDO heat transfer and rewetting was established. Based on the data base a new empirical correlation of PDO heat transfer was proposed. In addition, dynamic behavior of droplets (droplet size and velocity) and the thermal non-equilibrium were experimentally measured, which can be used for the validation and improvement of mechanistic models of PDO heat transfer and rewetting, also proposed by the research groups of the present authors. For the CFD prediction of CHF, a new and robust method for wall boiling heat transfer was developed to calculate the near wall void fraction and its connection to CHF.

Numerical study on heat transfer characteris tics of supercritical water in straight and helical tubes

The subcritical steam generators in high-temperature gas-cooled reactor pebble-bed modules can be replaced by supercritical steam generators to improve thermal efficiency. The axial and circumferential nonuniform flow and heat transfer characteristics of supercritical water in straight and helical tubes with varying inclinations (0–90°) are simulated to investigate the combined effects of tube structure, flow direction, thermophysical properties, property variations, buoyancy, and centrifugal forces. With heat fluxes of 233–930 kW/m2 and inlet mass fluxes of 225 or 1260 kg/(m2 s) under a working pressure of 24.5 MPa, the friction coefficients, turbulent kinetic energy, secondary flow, temperature, and heat transfer coefficients are studied in the cross section of variable structure tubes. The wall temperature and heat transfer coefficients of four regions are compared in straight and helical tubes; the maximum heat transfer coefficient appeared before the pseudo-critical point. The heat transfer coefficients are the greatest at the bottom of the straight tubes, where fluidity was high, and at the outer of the helical tubes, where the fluid velocity was high under centrifugal force. The secondary flow in the helical tubes causes a nonuniformity in the wall temperature, causing the circumferential maximum wall temperature to move.

Heat and mass transfer model for pork carcass precooling: Comprehensive evaluation and optimization

In this study, we construct a three-dimensional heat- and mass-transfer model to determine the moisture loss and spatio-temporal distribution of pork carcass temperature during precooling. We consider how convection, evaporation, and radiation affect the heat- and mass-transfer process and compare and analyze how precooling conditions affect the precooling rate, uniformity, and moisture loss of pork carcasses. The results reveal nonuniform precooling between different parts of single carcasses, mainly because of the nonuniform heat transfer on the pork carcass surface. However, for the overall precooling space, no significant difference appears in the rate of temperature decrease between individual carcasses. In addition, the ambient humidity most strongly affects carcass moisture loss, and the precooling temperature most strongly affects temperature uniformity and precooling rate. Finally, by comprehensively evaluating the effects of different precooling conditions on carcass precooling performance, the optimal precooling conditions are determined, namely, the air velocity, precooling temperature, ambient humidity, and initial carcass temperature of 10 m/s, 0 °C, 95 %, and 37 °C, respectively. This study thus provides an important theoretical basis and a useful reference for the determination of optimal precooling conditions and the comprehensive evaluation and optimization of pork carcass precooling.

Spatio-temporal progression and influencing mechanism of local wetting in membrane distillation

Membrane wetting is the bottleneck of membrane distillation (MD) in real applications. However, rare information is attainable on the spatial inhomogeneity and temporal instability of local wetting behavior along the membrane. In current study, the influences of operating conditions (i.e., feed temperature, velocity, and concentration) and membrane hydrophobicity on the spatio-temporal progression of local wetting along the membrane were evaluated using a non-invasive and online monitoring technique – ultrasonic time-domain reflectometry (UTDR). UTDR measurements could successfully distinguish local wetting dynamics and were validated by the off-line characterization of the wetting layer thickness via a scanning electron microscopy with energy-dispersive x-ray spectroscopy. Observations showed that the local wetting depth decreases along the feed flow direction. This wetting heterogeneity would be impaired with increasing surfactant concentration, feed temperature, and crossflow velocity. However, enhancing membrane hydrophobicity obviously reduced the rate of local wetting but hardly affected its nonuniform distribution. The wetting heterogeneous propagation at different locations is dominated by the nonuniform mass and heat transfer characteristics along the membrane based on the computational fluid dynamics (CFD) simulation. Localized wetting prevention near the module inlet is therefore critical to ensure stable MD operation.

A Water and Heat Coupling Model for GW-SW Interaction Considering Nonuniform Heat Transfer Effects of Soil.

An accurate groundwater-surface water (GW-SW) and heat coupling model (WHCM) aids in exploration of water migration and heat transport laws in the sedimentary layers of riverbeds and riparian zones, which is critical for understanding the transport patterns of contaminants in sediments. In this paper, a novel WHCM for GW-SW interaction is proposed by incorporating an effective soil thermal conductive model (ESTCM) into the advection-dispersion equation to address the shortcomings of current simulations that fail to account for the nonuniform heat transfer of soil. The model is developed in COMSOL, and the numerical implementation method is illustrated in detail. Furthermore, six recommended ESTCMs are examined in the WHCM to validate and compare the model simulation effects based on field test observations in the Walker River, USA. The results demonstrate that the proposed model performs better than the model that does not account for the nonuniform heat transfer effects of the soil in simulating GW-SW water and heat exchange. Meanwhile, the proposed model's simulation effects based on the Y2019 model perform the best. The orthogonal test revealed that the hydraulic conductivity ks and porosity n are the two most sensitive parameters influencing the model output results of groundwater seepage velocity and temperature, respectively. The efforts of this work can offer technical assistance and a guide for enhancing the simulation effect of river GW-SW water and heat exchange.

Research Progress on Convective Heat Transfer Characteristics of Supercritical Fluids in Curved Tube

Because of their compact structure, ease of processing and higher heat transfer coefficient, curved-tube heat exchangers are widely applied in various industry applications, such as nuclear power systems, solar-powered engineering, aircraft engine cooling systems and refrigeration and cryogenic systems. Accurate knowledge about the heat transfer characteristics of the supercritical fluids in the tube is critical to the design and optimization of a curved-tube heat exchanger. The available literature indicates that the flow of supercritical fluids flowing in curved tubes affected by the dual effects of the buoyancy force and centrifugal force is more complex compared to straight tubes. Therefore, to obtain insight into their unique characteristics and further research progress, this paper presents a comprehensive review of available experimental and numerical research works on fluids at supercritical pressure flowing in curved tubes. Overall, the secondary flow caused by the curvature enhances the heat transfer and delays the heat transfer deterioration, but it also causes a non-uniform heat transfer distribution along the circumferential direction, and the strengthening performance of the curved tube is damaged. Compared with the more mature theories regarding straight tubes, the flow structure, the coupling mechanism of buoyancy and centrifugal force, and the general heat transfer correlation of supercritical fluids in a curved tube still urgently need to be further studied. Most importantly, studies on the suppression of heat transfer oscillations and heat transfer inhomogeneities specific to curved tubes are scarce. Considering the current status and shortcomings of existing studies, some study topics for supercritical fluids in a curved tube are proposed.

Numerical analysis of the subcooled boiling phenomena in a wire-wrapped annulus

The wire-wrapped tight lattice fuel assembly is one of the options for small modular reactors. To investigate the performance of this assembly, the subcooled boiling characteristics in a wire-wrapped annular have been analyzed in the present work. The Eulerian two-fluid model coupled with the RPI wall boiling model was employed in the simulation. The mathematical models are validated by the subcooled boiling experimental data of the circular channel first, and then the simulation for wire-wrapped annular is carried out. The distributions of fluid temperature, wall temperature, vapor volume fraction, and heat flux partitions under a typical pressurized water reactor condition are gained. In the simulation conditions of the current wire-wrapped annular, the results indicate the non-uniform circumferential heat transfer can be ignored in subcooled boiling conditions, and the maximum vapor volume fraction occurred near the wire surface region. In addition, the increase of wire pitch increases the swirl intensity, at the same time, it also will increase the maximum vapor volume fraction near the rod surface region, which may cause DNB to occur earlier. Therefore, the wire pitch should be chosen carefully when the wire-wrapped assembly is applied to the pressurized water reactors. This work can provide a reference for the design of wire-wrapped tight lattice assembly applied in small modular reactors.

Optimising integrated heat spreaders with distributed heat transfer coefficients: A case study for CPU cooling

Increasing power densities of modern CPUs has led to regions of high temperature on the semiconductor die which can lead to performance and reliability problems. In this case study, the effect of imposing a non-uniform heat transfer coefficient profile across the convective surface the CPU's integrated heat spreader was investigated as a potential enhanced cooling concept. A finite element model of a copper heat spreader of 40 × 40 mm2 area and 2.5 mm thickness with a centred 13 × 13 mm2 heat source at 100 W/cm2 heat flux was considered to approximate typical modern high-powered CPUs. Both uniform and Gaussian distributions of the heat transfer coefficient were then considered. For the latter, both single and multi-objective Genetic Algorithm optimisation were carried out for three source temperature objectives; average temperature, maximum temperature and maximum temperature difference. The analysis showed that the multi-objective optimisation strategy produced the best overall heat transfer coefficient distribution, with almost 5 K reduction in both the maximum temperature and temperature gradient across the heat source compared with a uniform heat transfer coefficient distribution.

DNS analysis of flow and heat transfer of SCO2 in a square subchannel–Effect of gap width

The heat transfer and flow characteristics of supercritical carbon dioxide (SCO2) in a tight lattice are problematic in the thermal-hydraulic design of reactor fuel assemblies. Herein, direct numerical simulation (DNS) was performed to investigate the heat transfer and flow behavior of SCO2 in a vertically upward square subchannel. Emphasis was placed on clarifying the effect of the pitch-to-diameter (p/d) ratio, defined as the subchannel pitch over the rod diameter, on the time-averaged heat transfer and instantaneous velocity/temperature fluctuation. It was found that the wall temperature exhibits a “V-shaped” profile along the rod circumference, which is caused by the combined effects of buoyancy and an uneven flow area. The wall temperature is lower for subchannels with smaller p/d ratios; meanwhile, the circumferential non-uniform heat transfer becomes stronger, which also requires to be considered. The time-averaged streamwise velocity and fluid temperature have similar distributions on the subchannel cross-section, that is, high velocity and temperature occur near the rod gap, while regions with low velocity and temperature are identified in the subchannel interior. With an increase in the p/d ratio, both the temperature and velocity gradients are enlarged. Large-scale flow pulsations were identified in the subchannels. The instantaneous velocity fluctuation is weakened with increasing gap width; however, the fluctuation in the wall temperature exhibits an opposite trend. The effects of the p/d ratio on the dominant frequency of velocity/temperature fluctuation are not universal. Among the three selected cases, a subchannel with a small p/d ratio had a higher dominant frequency of instantaneous fluctuations. The turbulence structure was studied using a quadrant and anisotropy analysis. It was found that the outward and inward interactions included the main turbulence structures in the subchannel interior. In addition, with an increase in the p/d ratio, the transformation from disk-like turbulence to rod-like turbulence can be identified.

Wall‐resolved large eddy simulation of turbulent flows in helically ribbed steam cracker reactors

AbstractHelically ribbed coils are commonly applied in steam cracking furnaces. To fully understand the impact of these ribbed wall modifications on the local heat transfer and associated pressure drop throughout the reactor, detailed experimental, and numerical studies have been performed. Experimental data based on stereo‐particle image velocimetry (S‐PIV) and liquid crystal thermography have been used to validate the numerical results from wall‐resolved large eddy simulations using OpenFOAM. The validation shows an excellent agreement in terms of mean and fluctuating velocities, pressure drop, and heat transfer behavior in a discontinuously ribbed tube. Compared with the pressure drop in a continuously ribbed tube, an approximately 40% lower pressure drop is obtained with a discontinuously ribbed tube, at the cost of a slightly decreased heat transfer enhancement. This makes the discontinuously ribbed tube design particularly interesting for steam cracking applications. The results also show that the nonuniform heat transfer at the wall is inherently linked to the flow reattachment and recirculation zones caused by the rib. Finally, the validated numerical model was used to study comparable designs and propose novel helical rib designs. Based on the results of the study, enlarging the trailing edge of the conventional ribbed geometry will improve the thermal enhancement performance, and is therefore found most promising for steam cracking reactor design.

Flow and heat transfer performance of the channel with different shaped ribs cooled by mist/steam two-phase flow

The flow and heat transfer performance of mist/steam coolant in a straight channel with 45°/60°/75°V-shaped ribs, 45°/60°/75°/90°paralleled ribs and a smooth channel under different working conditions are studied. Based on vortex analysis, for mist/steam coolant, the regions where the Mainstream Secondary Flow Vortexes and the Longitudinal Secondary Flow Vortexes exist simultaneously can achieve better cooling performance. Among all mentioned rib structures, the 45°V-shaped ribbed passage achieves the best cooling enhancement, its sidewall average Nu number ratio is 33.8%–74.0% higher than the 90°paralleled ribbed channel. Although the heat transfer non-uniformity of the channel with 45°V-shaped ribs is not the lowest, it has lower heat transfer non-uniformity than the highest 45°paralleled ribbed channel. For mist/steam coolant, increasing inlet Re number, the sidewalls average Nu number ratio gradually decreases, but their heat transfer non-uniformity increases. As wall heat flux increases, the secondary flow vortexes in the channel does not change but both average Nu number ratio and the heat transfer non-uniformity clearly decreases. Raising mist/steam will not change the secondary flow vortexes structure. Instead, it will obviously increase the average Nu number ratio and heat transfer unevenness. Enlarging the mist diameter decreases the heat transfer performance of the sidewall, but also makes the sidewall heat transfer become less even.

Effect of initial solidification characteristics on longitudinal crack formation in thin slab caster

ABSTRACT Longitudinal surface crack has been one of the serious problems of thin slab casting (TSC). The present study was undertaken to comprehend the characteristics of longitudinal facial crack (LFC) and minimise the same in hot rolled low carbon steel sheets produced through thin slab casting and rolling (TSCR). Macro-structural characteristics of solidified shell has been investigated and correlated with plant observations. The centre and edges of funnel region showed maximum propensity of LFCs. TSC solidification is initiated with fine columnar dendrites which gradually coarsened towards the slab centre. This has been attributed to the characteristics of liquid steel flow instability in the upper mould region. Meniscus flow instability may lead to non-uniform heat transfer besides mould flux entrapment in the solidifying shell. Examination revealed that the mould hot faces ware covered with brass containing voids and cracks. Brass formation was found to be the most prominent around the meniscus of the wide hot face, which gradually faded out towards the mould exit. Tramp elements (zinc and lead) in liquid steel were found to be responsible for harmful brass formation during casting. The present findings were implemented in plant operation to minimise its concentration.

Numerical modeling of conjugate heat and mass transfer with water vaporization in solid materials inside a convective hot air tunnel

A two-dimensional conjugate model describes heat and mass transfer with liquid to vapor phase change of water in solid materials inside a hot air tunnel. Computational modeling allows to assess the evolution of convective fluid mechanics and heat convection in laminar airflow and coupled heat-mass transfer diffusion inside a rectangular solid. A transient finite volume method conjugate model characterizes the fluid mechanics and heat transfer in airflow, and the local convective heat (h(L)) and mass(hm(L)) transfer coefficients. The results indicate that h(L) was found to vary spatially on each surface of the solid between 5.71 and 101.62 W/m2K, while hm(L) varied from 5.05×10−6 to 1.38×10−6 m/s. Heat and mass transfer by unsteady diffusion inside the solid were accounted for by a second transient diffusion model. Experimental findings of apple slice dehydration kinetic reported in the literature allowed to validate the coupled heat and mass transfer model, with deviation lower than 2% for the water mass losses. Finally, the proposed model applied on a thin-layer of murta berry puree inside a hot air tunnel predicted transient non-uniform heat and mass transfer processes, with a difference of 13.5 K between the coldest and front areas.

Heat Transfer in Rotating, Trailing Edge, Converging Channels With Full- and Partial-Height Strip-Fins

Abstract A wide variety of pin-fins have been used to enhance heat transfer in internal cooling channels. However, due to their large blockage in the flow direction, they result in an undesirable high pressure drop. This experimental study aims to reduce pressure drop while increasing the heat transfer surface area by utilizing strip-fins in converging internal cooling channels. The channel is designed with a trapezoidal cross section, converges in both transverse and longitudinal directions, and is also skewed β=120deg with respect to the direction of rotation to model a trailing edge cooling channel. Only the leading and trailing surfaces of the channel are instrumented, and each surface is divided into 18 isolated copper plates to measure the regionally averaged heat transfer coefficient. Utilizing pressure taps at the inlet and outlet of the channel, the pressure drop is obtained. Three staggered arrays of strip-fins are investigated: one full-height configuration and two partial fin height arrangements (Sz = 2 mm and 1 mm). In all cases, the strip-fins are 2 mm wide (W) and 10 mm long (Lf) in the flow direction. The fins are spaced such that Sy/Lf = 1 in the streamwise direction. However, due to the convergence, the spanwise spacing, Sx/W, was varied from 8 to 6.2 along the channel. The rotation number of the channel varied up to 0.21 by ranging the inlet Reynolds number from 10,000 to 40,000 and rotation speed from 0 to 300 rpm. It is found that the full-height strip-fin channel results in a more nonuniform spanwise heat transfer distribution than the partial-height strip-fin channel. Both trailing and leading surface heat transfer coefficients are enhanced under rotation conditions. The 2 mm height partial strip-fin channel provided the best thermal performance, and it is comparable to the performance of the converging channels with partial-length circular pins. The strip-fin channel can be a design option when the pressure drop penalty is a major concern.

Modeling of the Nonuniform Microstructure and Microsegregation Formation of the Shell in Round Billet Continuous Casting

To explore the influence of nonuniform heat transfer on the grain structure and microsegregation of carbon in shells inside the mold, a multiscale model considering heat conduction and dendritic growth is constructed for the round billet continuous casting. Adopting measured heat flux as the boundary conditions, heat conduction in the mold is solved by the finite difference scheme, and dendritic growth is modeled by the cellular automaton model. The temperature distribution of the round billet under measured heat flux is calculated, and the grain structure and the microsegregation of carbon in four selected regions are simulated. Herein, it is shown in the results that the different local heat fluxes lead to dissimilar variations in the surface temperature and grain structure of the shell. A close relationship exists between the carbon microsegregation and local heat flux; the carbon microsegregation decreases with heat flux. The high heat flux accelerates columnar dendritic growth and fines the columnar dendritic array so that the secondary arms are less developed and the microsegregation is improved.

Influence of process layouts of multi-roll solid-liquid cast-rolling bonding process on circumferential performance uniformity during fabricating metal cladding materials

The twin-roll casting (TRC) process is typically used to fabricate laminated metal cladding strips with rectangular cross-sections, and it has the advantages of short flow, low energy consumption, green environmental protection, etc. Recently, a twin-roll solid-liquid cast-rolling bonding (TRSLCRB) process was proposed based on the TRC process to fabricate metal cladding materials with round cross-sections. However, the nonuniformity of heat transfer and mass transfer along the circumferential direction finally influences the performance uniformity. Therefore, a multi-roll solid-liquid cast-rolling bonding (MRSLCRB) process was proposed integrating cast-rolling bonding technology and multi-roll groove rolling technology. The steady-state thermal resistance network was established, and the influences of nominal roll radius, groove radius, and molten pool height on the heat transfer and mass transfer were studied systematically. 3-D steady-state thermal-fluid coupled simulation models of twin-roll, three-roll, and four-roll layouts were established. The results indicate that increasing casting roll number can improve the nominal cast-rolling velocity, service life of the casting roll, temperature uniformity, strain uniformity, and strain rate uniformity through regulating the heat transfer and mass transfer. Considering the manufacturing feasibility, the MRSLCRB equipment based on the three-roll layout was designed. Cu/steel cladding bars with uniform circumferential performance were fabricated, and the forming mechanism was revealed. The multi-field coupled analysis method provides a way to control heat and mass transfer uniformity, and the successful attempts of various typical metal cladding materials inspire exploring new forming processes.

Numerical methodology based on fluid-structure interaction to predict the residual stress distribution in glass tempering considering non-uniform cooling

In this paper a novel numerical methodology for calculating non-uniform residual stress distributions during the glass tempering process is presented. Tempering techniques lead to non-uniform heat transfer rates causing residual stress inhomogeneities, which consequently have a direct impact on the structural behaviour of components. Nevertheless, most works in the literature do not consider the influence of local flow phenomena during thermal calculations, resulting in non-representative residual stress distributions. In this context, a novel generalised methodology based on a fluid–structure interaction one-way approach to sequentially couple the thermal and mechanical fields is presented. In this way, the unsteady and non-uniform heat transfer rate is coupled with the Narayanaswamy model to predict the non-homogeneous residual stress pattern. The obtained numerical results for the analysed impinging jet array case are in good agreement both quantitatively and qualitatively, exhibiting an average error below 10% with respect to previous experimental investigations. Finally, efforts are made to reduce the computational time. Therefore, the proposed methodology proves to be an efficient tool for understanding the underlying mechanisms and predicting the residual stress distributions during glass tempering.

Non-uniform heat transfer behavior of wet foam fluid in a narrow fracture channel

The heat transfer characteristic of wet foam fluid in some channels has not been fully understood due to its special evolution characteristic. In this study, we explore distribution laws for the temperature and the heat transfer coefficient of the VES-CO2 foam fluid on the heating surface of a narrow fracture channel. The results show that the heat transfer coefficient of foam fluid on the heating surface is affected by multiple factors, such as the foam quality, foam structure, inclined channel and so on. We find that the temperature on the middle part of the heating surface is higher. Especially, due to the drainage of the flowing wet foam, there are different heat transfer characteristics in the middle and at the side of the heating surface. The heat transfer coefficient displays fluctuation behavior at the side of the heating surface. In the inclined channel, the heat transfer coefficient increases with the inclination angle for the positive inclination, and for the lateral inclination, the average cross-sectional heat transfer coefficient decreases with increasing inclination angle. In the low-permeability oil and gas development, this research has important significance for understanding the heat transfer phenomenon of wet foam fluid in formation fracture. It is also expected that this study could provide a reference for related application of wet foam fluid in some special channels.

Effect of frequency ratio of inclined rotating control on the flow characteristics of impinging jet using DNS

Since the heat transfer performance of the impinging jets decreases rapidly away from the stagnant region, it is necessary to eliminate the non-uniform heat transfer distribution and to increase the heat transfer area. It has been shown that the combination of inclined and rotating control of the jet and axial excitation produces a bifurcation structure of the jet characteristic of blooming jets, resulting in high mixing performance. In addition, the DNS of this blooming jet when it is impinged on a wall reveals that the Nu number distribution and the heat transfer distribution change significantly depending on the impinging distance. Therefore, this study investigates the flow characteristics and heat transfer performance when the frequency ratio is varied in addition to the impingement distance.