Three-dimensional Computational Fluid Dynamics Simulations Research Articles

Temperature distribution analysis and mechanical property prediction of wire loops in the Stelmor air-cooling system

During the Stelmor air-cooling process, the temperature distribution has a significant impact on the wire loops' final mechanical properties. The temperature distribution during air-cooling process is accurately solved by establishing three-dimensional model and Computational Fluid Dynamics (CFD) simulation. It is also found that the heat transfer coefficient on the cross section of the wire loop is very different, with a difference of 70–100 Wm−2K−1. The average value of the surface heat transfer coefficient of the wire loops section is used to replace the surface heat transfer coefficient of the wire loops, which improves the temperature distribution calculation accuracy, which is not considered by previous scholars. The finite difference method is used to calculate the mathematical model of the temperature distribution during the Stelmor air-cooling process. It is found that the maximum temperature difference of the wire during the cooling process is 90–110 K. The prediction model of mechanical property of wire after air-cooling was established, and distribution of mechanical property of the wire loops was obtained, and the reason for the uneven distribution of mechanical property of the wire loops was found.

Full-scale numerical simulations of standing-wave thermoacoustic engines with circular-pore and pin-array stacks

Thermoacoustic engines (TAEs) can convert thermal energy into acoustic energy with no moving parts. Previous numerical studies normally focused on the TAEs with a parallel-plate stack due to their simple structures and used two-dimensional (2-D) computational fluid dynamics (CFD) models to save computational costs. In this study, we conduct full-scale three-dimensional (3-D) CFD simulations on the standing-wave TAEs with more complicated circular-pore and pin-array stacks. Firstly, the dynamic behavior of the standing-wave TAEs in the start-up process is investigated. It is found that the optimal ratios of hydraulic radius rh to thermal penetration depth δk for the TAEs with circular-pore and pin-array stacks are 2 and 3.2, respectively. Secondly, the acoustic, hydrodynamic, and thermodynamic characteristics of the standing-wave TAEs in the steady-state process are explored. We find that when operating at optimal rh/δk, the TAE with a pin-array stack generates much larger acoustic power than that with a circular-pore stack. Examination of the vortex shedding at the stack ends indicates that the pin arrays exhibit less flow resistance than circular pores. At optimal rh/δk, the time-averaged transversal heat flux at the pin array ends is calculated to be around 1.2 × 105 W/m2, which is larger than 7.5 × 104 W/m2 of circular pores, corresponding to a better thermodynamic performance. The 3-D numerical investigations in this work give deeper insights into the performances of TAEs with circular-pore and pin-array stacks which were investigated in experiments, providing useful guidance for the future design and development of more sophisticated thermoacoustic devices for low-grade heat recovery.

CFD simulation and experimental study of CO2 absorption in a rotating packed bed

The rotating packed bed (RPB), a process intensification equipment, has been widely studied and applied to chemical engineering processes such as gas absorption, nanomaterial preparation, and polymer devolatilization. In this study, we presented a typical RPB model to study the intensification mechanism of high gravity on gas-liquid mass transfer. Based on this, three-dimensional computational fluid dynamics (CFD) simulations and experiments of CO2 physical absorption were conducted to investigate the gas-liquid mass transfer characteristics in the RPB. The predicted and experimental values of CO2 saturation rates of the liquid phase showed good agreement, and the errors were within ± 15 % under various operating conditions. Moreover, detailed flow field and mass transfer information that are difficult to measure experimentally, such as the distribution of CO2 mass fraction in the liquid, liquid holdup, turbulent kinetic energy dissipation rate, and gas-liquid interfacial area, were analyzed by CFD simulation results. These results provide a solid foundation for the further development and application of RPB.

Numerical Simulation of the Interaction between a Planar Shock Wave and a Cylindrical Bubble

Three-dimensional (3D) computational fluid dynamics (CFD) simulations have been carried out to investigate the complex interaction of a planar shock wave (Ma = 1.22) with a cylindrical bubble. The unsteady Reynolds-averaged Navier–Stokes (URANS) approach with a level set coupled with volume of fluid (LSVOF) method has been applied in the present study. The predicted velocities of refracted wave, transmitted wave, upstream interface, downstream interface, jet, and vortex filaments are in very good agreement with the experimental data. The predicted non-dimensional bubble and vortex velocities also have great concordance with the experimental data compared with a simple model of shock-induced Rayleigh–Taylor instability (i.e., Richtmyer–Meshkov instability) and other theoretical models. The simulated changes in the bubble shape and size (length and width) against time agree very well with the experimental results. Comprehensive flow analysis has shown the shock–bubble interaction (SBI) process clearly from the onset of bubble compression up to the formation of vortex filaments, especially elucidating the mechanism on the air–jet formation and its development. It is demonstrated for the first time that turbulence is generated at the early phase of the shock cylindrical bubble interaction process, with the maximum turbulence intensity reaching about 20% around the vortex filament regions at the later phase of the interaction process.

Enhancing Axial Flow Fan Performance in Air-Cooled Condensers: Tip Vortex Manipulators and Comparative Analysis of Numerical Simulation and Experimental Testing

Abstract Direct dry-cooled power plants typically operate numerous large-diameter axial flow fans in air-cooled condensers (ACCs) to facilitate the condensation of steam in the plant's thermodynamic cycle. Enhanced fan efficiency may, at scale, lead to significant parasitic power reductions and subsequent increases in plant power output. The performance of these fans may be increased by adding blade-tip modifications, which act to control blade-tip leakage flow. Previous studies have shown that manipulating the tip leakage vortex (TLV) increases the blade-to-air momentum transfer and stabilizes the air flow structures as it traverses the fan blade. This paper takes a step toward the development of improved tip vortex manipulators for an ACC fan. Three-dimensional computational fluid dynamics (CFD) simulations, and experimental testing of the modified and unmodified fan within an ISO test facility are performed. The results are then utilized to assess the accuracy of the simulation model, visualize the manipulated flow structures at the blade tip, and ultimately quantify the effect of the endplate designs on fan performance. Excellent correlation between numerical and test results for the unmodified fan is observed, and the benefit of blade-tip modification on fan performance is again confirmed experimentally. The simulation model, however, fails to predict improvements in fan performance under modification, and simulated tip leakage flows are investigated for clarification. It is hypothesized that deflection of tip endplates under operation account for differences between simulation and experiment, and that fluid–structure interaction analyses could potentially resolve discrepancies.

Unveil carbon dioxide recycling potential throughout distributor-type membrane reactor

With the cost of green hydrogen production decreasing year by year, methanation, a carbon dioxide hydrogenation reaction, is becoming a more critical technology for the realization of a carbon-neutral society. Here, we show the procedure of membrane preparation for a distributor-type membrane reactor that simultaneously captures and recycles CO2 together with experimental tests of the proposed reactor design. To decrease the temperature gradient in the reactor and to improve methane recovery from the inlet gas mixture, a three-dimensional computational fluid dynamics simulation of the reactor was conducted. The numerical results suggest that the distributed feed design results in a uniform distribution of carbon dioxide, preventing localized reactions at the reactor inlet. In addition, it reduces the temperature rise in the reactor by up to about 300 K compared to the case where the carbon dioxide and hydrogen gas mixture is fed from a single inlet. The effect of the feed CO2 concentration on reactivity is also discussed. Simulation results show that the membrane reactor with inlet concentration of about 15 %, such as those emitted from industrial boilers, is capable of recovering methane at concentrations about 1.5 times higher in comparison to 100 % CO2 concentration at the inlet in a classical reactor.

The Impact of High-Rise Building Shapes on Wind Flow Characteristics and Energy Potential

In recent years, wind energy has become a potential source of low carbon energy. The shape of a building is a significant factor in aerodynamics, providing an opportunity for wind power control and wind energy proliferation. This research project aims to study the design of high-rise buildings and investigate how wind affects energy absorption by developing an aerodynamic optimization procedure (AOP) and using Computational Fluid Dynamics (CFD) in COMSOL Multiphysics. This study aimed to optimize the building shape for wind energy exploitation. Optimizing the building shape in the early stages of design enables the control of wind-induced loads and responses and reduces the energy demand in high-rise buildings, where resource consumption is higher than that in low-height buildings. This study used a three-dimensional CFD simulation of wind loading on tall buildings to optimize the building shape. This research will provide valuable insights for architects, engineers, and building developers to design and optimize high-rise buildings for wind energy exploitation, reduce the carbon footprint, and improve the energy efficiency of buildings.

Nonlinear Acoustic Behavior Prediction and Analysis of Straight Through Perforated Tube Silencer With Flow

Straight through perforated tube silencers are widely used in intake and exhaust noise control, and their acoustic behaviors are influenced by the gas flow and high amplitude sound remarkably. To investigate the acoustic attenuation performance of straight through perforated tube silencers in the presence of flow and high amplitude sound, an approach based on the three-dimensional (3D) time-domain computational fluid dynamics (CFD) simulation is employed and validated by comparing predictions and measurements. Transmission loss of the straight through perforated tube silencer under pure tone and multi-tone sound excitations is predicted. Results show that, under the pure tone sound excitations, the acoustic attenuations are affected remarkably by the high amplitude sound, and the nonlinear effects turn to weaken as flow velocity increases. With the sound pressure level (SPL) decreasing along the axis of the silencer, the acoustic nonlinearity in the orifice weakens gradually. The shedding vortices are restricted to the region near perforations because of the transport of flow. When the multi-tone sound excitation is enforced on the inlet, transmission loss of the silencer is different from the pure tone excitation at the same SPL of every compositional frequency.

Influence of posture during gliding flight in the flying lizard Draco volans

The agamid lizards of the genus Draco are undoubtedly the most renown reptilian gliders, using their rib-supported patagial wings as lifting surfaces while airborne. Recent investigations into these reptiles highlighted the role of body posture during gliding, however, the aerodynamics of postural changes in Draco remain unclear. Here, we examine the aerodynamics and gliding performances of Draco volans using a numerical approach focusing on three postural changes: wing expansion, body camber, and limb positioning. To this aim, we conducted 70 three-dimensional steady-state computational fluid dynamics simulations of gliding flight and 240 two-dimensional glide trajectory calculations. Our results demonstrate that while airborne, D. volans generates a separated turbulent boundary layer over its wings characterized by a large recirculation cell that is kept attached to the wing surface by interaction with wing–tip vortices, increasing lift generation. This lift generating mechanism may be controlled by changing wing expansion and shape to modulate the generation of aerodynamic force. Furthermore, our trajectory simulations highlight the influence of body camber and orientation on glide range. This sheds light on how D. volans controls its gliding performance, and conforms to the observation that these animals plan their glide paths prior to take off. Lastly, D. volans is mostly neutral in pitch and highly maneuverable, similar to other vertebrate gliders. The numerical study presented here thus provides a better understanding of the lift generating mechanism and the influence of postural changes in flight in this emblematic animal and will facilitate the study of gliding flight in analogous gliding reptiles for which direct observations are unavailable.

Three-dimensional transient CFD simulation of lignite chemical looping gasification in a circulating fluidized bed

In this work, a full-loop 3D computational fluid dynamics (CFD) numerical simulation of the chemical looping gasification (CLG) process of lignite in a circulating fluidized bed (CFB) was performed using a two-fluid Eulerian-Eulerian model. The results showed that the CFD simulation effectively captured the axial and radial velocities of the particles. More radial flow occurred in the bottom part of the riser and inside the cyclone. The exothermic reaction became dominant within 7s, while the heat-absorbing reaction became dominant between 7 and 15s. The aggregation regions of syngas moved up with that of the high-temperature zone, and CO was the main contributor to the syngas. The particle size in the range of 175–225 μm was inversely proportional to the size of the average heat transfer coefficient (HTC) in the riser. Extremely small particle size saturated the bed, suppressing the HTC. The peak of the HTC was 387.7 W/(m2·K), which occurred in the upper-middle region of the riser and reached. The maximum HTC average value was 180.6 W/(m2·K). Finally, experimental data were used to verify the reliability of the model.

Numerical analysis of flow mechanism between sealing flow and mainstream exhausted from pulse detonation combustor

A conventional axial turbine drived by a pulse detonation combustor heavily challenges the turbine cooling and hot gas sealing. In order to fully understand the physical behavior of ingress and egress effect with the pulse inlet mainstream, a study is carried out to investigate the unsteady flow field and sealing efficiency inside the cavity using the method of unsteady, three-dimensional Computational Fluid Dynamic simulation. The pulse detonation inflow boundary condition simplified using simple exponential decay formulas are applied to the inlet of mainstream passage. The results reveal that the magnitude of sealing gas pressure does affect the pressure and sealing efficiency distribution inside cavity. The sealing efficiency inside the cavity goes through three sub-stages, respectively, "the decline stage", "the plateau stage" and "the recovery stage". when the sealing gas pressure increases, the sealing efficiency of these three sub-stages will increase, and the duration of "the plateau stage" and "the recovery stage" will decrease. As a result, the ability of turbine cavity that resist the ingress of pulse detonation inflow can be augmented with the sealing gas pressure increases.

Three-dimensional CFD simulation of geyser boiling in high-temperature sodium heat pipe

A deep understanding of the characteristics and mechanism of geyser boiling and capillary pumping is necessary to optimize a high-temperature sodium heat pipe. In this work, the Volume of Fluid (VOF) two-phase model and the capillary force model in the mesh wick were used to model the complex phase change and fluid flow in the heat pipe. Computational Fluid Dynamics (CFD) simulations successfully predicted the process of bubble nucleation, growth, aggregation, and detachment from the wall in the liquid pool of the evaporation section of the heat pipe in horizontal and tilted states, as well as the reflux phenomenon of capillary suction within the wick. The accuracy and stability of the capillary force model within the wick were verified. In addition, the causes of geyser boiling in heat pipes were analyzed by extracting the oscillation distribution of heat pipe wall temperature. The results show that adding the capillary force model within the wick structure can reasonably simulate the liquid backflow phenomenon at the condensation; Under the horizontal and inclined operating conditions of the heat pipe, the phenomenon of local dry-out will occur, resulting in a sharp increase in local temperature. The speed of bubble detachment and the timely reflux of liquid sodium (condensate) replenishment in the wick play a vital role in the geyser temperature oscillation of the tube wall. The numerical simulation method and the results of this study are anticipated to provide a good reference for the investigation of geyser boiling in high-temperature heat pipes.

Combustion mechanism study of ammonia/n-dodecane/n-heptane/EHN blended fuel

Due to the challenges of ammonia, such as high ignition energy and slow flame propagation speed, the utilization of ammonia in engines might necessitate the implementation of dual-fuel combustion modes along with the use of cetane improvers. To optimize the performance of ammonia-fueled engines, and achieve efficient and clean combustion, three-dimensional computational fluid dynamics (CFD) simulations are imperative. However, prior to conducting a three-dimensional CFD study, an accurate reaction mechanism for each component is essential. In this study, the blending mechanisms of ammonia, n-dodecane, and 2-ethylhexyl nitrate (EHN) were constructed using CHEMKIN software, including 243 species and 1293 reactions. The calculated results of ignition delay, laminar flame velocity, and the concentration of significant species agreed well with experiment results. The ignition delay, laminar flame velocity, adiabatic flame temperature, and the concentration of major products were analyzed in different blending ratios. The use of high cetane fuel shortens ignition delay and increases laminar flame speed. As the equivalence ratio of ammonia increases, the concentration of NO decreases while the concentration of H2 increases. The combustion process is also analyzed based on optical diagnostic results, and the impact of the ammonia/n-dodecane mixtures blended with EHN on the combustion process is investigated. The addition of EHN proved to shorten the ignition delay of the mixture. Furthermore, the introduction of EHN exhibits marginal influence on NOx generation, with the predominant augmentation of NOx emissions stemming from fuel-derived NOx resulting from the fuel's inherent nitrogen content. Due to the small amount of EHN added, the overall impact is relatively small.

Realistic fuel spray modeling for gasoline direct injection engine applications

Fuel spray modeling plays a critical role during modern gasoline direct injection (GDI) engine development due to fuel injection’s dominant impact on engine performance and emissions as well as the complex physical processes involved. In engineering three-dimensional (3D) computational fluid dynamics (CFD) simulations, the liquid-phase fuel atomization, evaporation, and mixing are usually modeled with the discrete droplet model (DDM) adopting a Lagrangian approach for multiphase CFD simulations. To this end, general practices heavily depend on the reduced order characterization of the injector nozzle flow. However, such simplified injector modeling may lead to insufficient representations of the complex spray dynamics. To tackle this problem, this study proposes a novel workflow to numerically evaluate GDI sub-cooled and flash-boiling sprays under engine-relevant conditions using a side-mounted GDI injector together with real gasoline fuel properties. The workflow introduces a one-way coupling (OWC) method leveraging high-fidelity nozzle flow simulations to provide realistic boundary conditions to the Lagrangian injector model. The proposed workflow was first verified in a constant volume chamber (CVC) environment and then implemented in a practical GDI engine setup to study spray morphology, fuel-air mixing, and wall-wetting propensity. In addition, detailed comparison was performed between the OWC method and the conventional rate of injection (ROI) routine. Quantitative analysis of spray characteristics was conducted to highlight possible source of discrepancies of the conventional ROI method.

The improvements of a diesel engine fueled with renewable and sustainable diesel/n-butanol/polyoxymethylene dimethyl ethers blended fuels at high altitudes

Atmospheric conditions at high altitudes deteriorate combustion in the cylinder of compression ignition (CI) engines, severely degrading engine performance and increasing soot emissions. The use of oxygenated fuels as an alternative fuel to diesel is an effective solution to improve performance and reduce emissions of highland CI engines. Before optimizing a highland CI engine, it is necessary to determine the law of influence of oxygenated fuels on the performance and emission characteristics of the engines. This paper focuses on the effect of diesel/n-butanol/polyformaldehyde dimethyl ether blends on the combustion, performance, and emission characteristics of a CI engine at different simulated altitudes (0 m, 2000 m, 3000 m, and 4000 m). First, a three-dimensional computational fluid dynamics (3D-CFD) simulation model was developed and validated by experimental results. Second, the 3D-CFD model coupled with a chemical kinetic mechanism including 164 species and 643 reactions was used to simulate the combustion process in the cylinder under different operating conditions. The results showed that the high-altitude environment increased the cylinder temperature, peak heat release rate, ignition delay, soot emissions, HC emissions, and brake specific fuel consumption, and reduced BTE, and NOx emissions of the CI engine compared with the plains. At the same altitude, the use of n-butanol and PODE3 provided oxygen for in-cylinder combustion, which somewhat promoted more complete combustion in the cylinder, reduced HC and soot emissions and increased BTE. Although the use of oxygenated fuels in highland CI engines elevated NOx emissions, the problem could be solved by methods such as LTC and SCR. Overall, n-butanol and PODE3 are promising alternative fuels for highland CI engines, mitigating to some extent the problems of higher soot and HC emissions and lower BTE associated with high-altitude environments.

An analytical linear two-dimensional actuator disc model and comparisons with computational fluid dynamics (CFD) simulations

Abstract. The continuous up-scaling of wind turbines enabled by more lightweight and flexible blades in combination with coning has challenged the assumptions of a plane disc in the commonly used blade element momentum (BEM)-type aerodynamic codes for the design and analysis of wind turbines. The objective with the present work is thus to take a step back relative to the integral 1-dimensional (1-D) momentum theory solution in the BEM model in order to study the actuator disc (AD) flow in more detail. We present an analytical, linear solution for a two-dimensional (2-D) AD flow with one equation for the axial velocity and one for the lateral velocity, respectively. Although it is a 2-D model, we show in the paper that there is a good correlation with axis-symmetric and three-dimensional (3-D) computational fluid dynamics (CFD) simulations on a circular disc. The 2-D model has thus the potential to form the basis for a simple and consistent rotor induction model. For a constant loading, the axial velocity distribution at the disc is uniform as in the case of the classical momentum theory for an AD. However, an important observation of the simulated flow field is that immediately downstream of the disc the axial velocity profiles change rapidly to a shape with increased induction towards the edges of the disc and less induction on the central part. This is typically what is seen at the disc in full non-linear CFD AD simulations, which is what we compare with in the paper. By a simple coordinate rotation the analytical solution is extended to a yawed disc with constant loading. Again, a comparison with CFD, now with a 3-D simulation on a circular disc in yaw, confirms a good performance of the analytical 2-D model for this more complicated flow. Finally, a further extension of the model to simulate a coned disc is obtained using a simple superposition of the solution of two yawed discs with opposite yaw angles and positioned so the two discs just touch each other. Now the validation of the model is performed with results from axis-symmetric CFD simulations of an AD with a coning of both 20 and −20∘. In particular, for the disc coned in the downwind direction there is a very good correlation between the simulated normal velocity to the disc, whereas some deviations are seen for the upwind coning. The promising correlation of the results for the 2-D model in comparison with 3-D simulations of a circular disc with CFD for complicated inflow like what occurs at yaw and coning indicates that the 2-D model could form the basis for a new, consistent rotor induction model. The model should be applied along diagonal lines on a rotor and coupled to an angular momentum model. This application is sketched in the outlook and is a subject for future research.

Validation of mesoscience-based structural model for simulating gas–solid flows in circulating-turbulent fluidized beds

The circulating-turbulent fluidized bed (CTFB) is an important fluidization regime that can maintain a high solid concentration and high reaction intensity as in turbulent fluidized bed, and suppress solids back-mixing as in circulating fluidized bed. Computational fluid dynamics (CFD) studies on it are however very sparse. In this study, extensive three-dimensional CFD simulations of CTFB are carried out using the mesoscience-based structural model (Liu et al., 2023), where the gas-rich dilute phase and the particle-rich dense phase are defined as the two interpenetrating continua, instead of treating the gas and particles as the two interpenetrating continua as in classical two-fluid models. It is shown that the model is able to faithfully predict the hydrodynamics of CTFB, in terms of axial and radial solid concentration profiles and radial solid velocity profiles. This study not only provides a systematical CFD study on the hydrodynamics of gas–solid flow in CTFB but also offers validations of the mesoscience-based structural model via simulating the hydrodynamics of new fluidization regime (CTFB).

CFD simulation and optimization of an industrial cement gas–solid air classifier

An air classifier is one of the main and effective devices in cement industry. In this study, a three-dimensional, steady and two-phase (solid-gas) computational fluid dynamics (CFD) simulation was performed to optimize the performance of this device in the Kerman Momtazan cement plant, Iran. After the validation of CFD results, the air flow field and air path lines between fixed blades were checked carefully and the non-uniformity in velocity distribution and the formation of vortex flows between the blades close to particle inlets were observed. The study tried to improve the device efficiency by changing the method of entering particles into the device, resulting in a reduction in air classifier electrical energy consumption (from 41 to 35 (kW h)/t) and an increase in production rate (from 203 to 214 t/h). Additionally, the study investigated the effects of other modifiable operating conditions like rotary cage rotation speed, pressure difference, and inlet air temperature on the particle size distribution and classifier efficiency. The results showed that increasing the cage rotation speed decreased the product rate and the product particles mean diameter while increasing pressure difference or increasing temperature increased the product rate and the product particles mean diameter. It was concluded that these modifiable operating conditions can significantly affect the performance of the air classifier in the cement industry.

Multi-Objective Optimization of Air-Cooled Perforated Micro-Pin Fin Heat Sink Via an Artificial Neural Network Surrogate Model Coupled With NSGA-II

Abstract This research aims to create an artificial neural network (ANN) regression model for predicting the performance parameters of the perforated micro-pin fin (MPF) heat sinks for various geometric parameters and inflow conditions. A three-dimensional computational fluid dynamics (CFD) simulation system is developed to generate dataset samples under different operational conditions, which are specified using Latin hypercube sampling (LHS). An ANN model is first obtained by optimizing the model hyper-parameters, which are then deployed to learn from the input feature space that consists of perforation diameter, perforation location, and inflow velocity. For accurate training of the ANN, the model is trained over a range of uniformly distributed data points in the input feature space. The developed multi-layer model predicted Nusselt number and friction factor with the mean absolute percentage error of 4.45% and 1.80%, respectively. Subsequently, the developed surrogate model is used in the optimization study to demonstrate the application of the surrogate model. A multi-objective non-dominated sorting genetic algorithm (NSGA-II) is used to perform the optimization of the perforation location, diameter, and inflow conditions. Negative of the Nusselt number and friction factor are chosen as objectives to minimize. A Pareto front is obtained from the optimization study that shows a set of optimal solutions. Thermal performance of the perforated MPF is increased between 11.5% and 39.77%. The optimizer selected a significantly smaller hole diameter at a higher location and a faster speed to maximize the Nusselt number and minimize the friction factor.

Heat Transfer Enhancement by Mitigating the Adverse Effects of Crossflow in a Multi-Jet Impingement Cooling System in Hexagonal Configuration by Coaxial Cylindrical Protrusion—Guide Vane Pairs

A novel compound multi-jet impingement system for enhanced cooling of a flat surface by augmenting its area with cylindrical protrusions (CPs) equipped with coaxial guide vanes (CGVs) and reducing deflection of jets by crossflow has been developed for high-heat removal applications. The cooling performance of coaxial circular jets impinging on the top faces of CPs placed in hexagonal configuration on a flat plate is evaluated by three-dimensional (3D) computational fluid dynamics (CFD) simulations. Jets impinging on the top faces of the protrusions are directed to their lateral faces and then to the base plate by the CGVs around the protrusions, resulting in up to 62.8% improvement in heat transfer rate with a minor increase in pressure drop. Effects of protrusion height and diameter on the pressure drop and cooling performance are studied for jet Reynolds (Re number range of 5000–20,000. Due to both shortened jet impingement lengths as the height of protrusions is increased and directing the expended fluid away from the impinging jets by CGVs, adverse effects of jet–crossflow interactions on cooling performance and fluid pumping power are significantly reduced. Performance evaluation criterion (PEC) of the novel compound multi-jet impingement cooling system (CMJICS) can be as high as 1.52.