Pin Fin Shapes Research Articles

Extensive computational fluid dynamics analysis of microchannel flow topology and friction factor in arrays of conical pin-fins

The design of integrated circuits presents an increasing challenge for engineers, who seek to identify effective methods for cooling the miniature electronic components that are becoming increasingly complex. One potential solution is the use of micro pin-fin heat sinks, which have the potential to be an effective thermal management technique. This study compares the potential thermo-hydraulic efficiency of micro heat exchangers with conical pin-fins, arranged in two alternative patterns. The flow topology was investigated using the critical points theory and Ω-criteria to gain a deeper understanding of vortical structures and flow separation. 75 variations of pin-fin arrays were simulated and analyzed. It is noteworthy that no pattern similar to bidirectional pin-fins has been studied previously. The input datasets for the simulations included pitch/height ratios ranging from 0.823 to 1.235, cone angles from 0° to 13.48°, and flow Reynolds numbers of 40–117. The numerical results show that Ω and kinetic energies can predict the onset of instabilities. The degree of conicity and the pattern affect the friction factor, typically reducing it. The conical shape and arrangement of pin-fins can also aid in stabilizing the flow. Furthermore, the dependence of the friction factor on pitch/height and Reynolds was quantified with the calculated mean relative error of 1.7%. Moreover, turbulence parameters and friction factors were used to evaluate the thermohydraulic properties, deliberately excluding heat transfer simulations. This approach allows a much wider range of geometric modifications to be investigated for the preliminary optimization of the thermal and hydraulic performance of microchannels.

A Review on Application of Pin-Fins in Enhancing Heat Transfer

The pin-fin is one of the main technologies in enhancing heat transfer. The accelerated flow and vortex structures are produced, which can disrupt the development of the flow boundary layer. The configuration of the pin-fin is obvious for heat transfer and flow characteristics, including its shape, size, and arrangement in the cooling channel. This work provides a detailed introduction to the application of pin-fins in enhancing heat transfer and reducing flow resistance, including the conventional shapes, improved shapes based on circular pin-fins and irregular shapes. At the same time, the influence of the diameter, height and density of pin-fins on heat transfer and flow performance is studied, and the influence mechanism is analyzed from the perspective of boundary layers. In addition, some applications that combine pin-fins with other cooling methods to further improve performance are analyzed. In terms of the optimization technology, the structure optimization for pin-fin shape and the layout optimization for pin-fin array are summarized. Therefore, this review provides a wide range of literature for the design of internal cooling channel pin-fins.

Effect of Shape and Placement of Twisted Pin Fins in a Rectangular Channel on Thermo-Hydraulic Performance

Effect of Shape and Placement of Twisted Pin Fins in a Rectangular Channel on Thermo-Hydraulic Performance

Optimising shapes of multiple pin fins in a microchannel using deep reinforcement learning and mesh deformation techniques

The utilisation of advanced pin fin designs in microchannels is useful for enhancing cooling efficiency. Advancements in machine learning and processing power have sparked interest in shape optimisation techniques. This research employs a novel framework that integrates Deep Artificial Neural Networks and Reinforcement Learning with a Computational Fluid Dynamics (CFD) solver to optimise multiple pin fin shapes within a microchannel. By incorporating Radial Basis Function interpolation and Proximal Policy Optimisation alongside FLUENT, acting as the CFD environment, the reinforcement learning agent adeptly explores the design space to enhance the thermohydraulic performance factor (TPF), aiming to maximise Nusselt number while minimising pressure loss. Unlike previous heat transfer optimisation studies, which typically required mesh regeneration at each step, the proposed framework could bypass the meshing step and alter the geometry directly by relying on the RBF interpolation technique to deform the mesh directly. Three distinct scenarios investigated in this study are uniform deformation of all pin fins, deformation of all pin fins arranged in two rows, and individual deformation of each pin fin. Extensive simulations, exceeding 90,000 different cases, demonstrate that although the optimisation process for the individual deformation of each pin fin requires more iterations compared to others, it surpasses them in terms of TPF improvement. Notably, significant improvements are achieved, such as a 49 % enhancement in Nusselt number and a 33 % reduction in pressure drop, culminating in an impressive 63 % increase in TPF compared to the initial geometry.

A novel pin finned structure-embedded microchannel heat sink: CFD-data driven MLP, MLR, and XGBR machine learning models for thermal and fluid flow prediction

Microscale mechanical systems benefit from microchannel heat sinks' heat transfer efficiency. This study uses six new pin fin shapes embedded in microchannel to improve heat dissipation. The study optimizes geometries based on overall thermal performance for Reynolds numbers ranging from 150 to 350. Validation using numerical and experimental data indicates variations under 10 %. Graphical representations show that the proposed pin fin configurations outperform the baseline case. From numerical investigation, the circular perforated fish fin increases Nusselt number by 25 %, whereas the elliptical fin lowers pressure loss by 66.95 %. Elliptical fins enhance thermal performance by 30 %, proving that novel designs and optimization tactics work. Six machine learning models are considered to predict Nu and pressure drop. Keras and sklearn were used for MLP, MLR, and XGBR was imported from XGBoost. Model performance was assessed using the R2 test, MRE, RMSE, and rRMSE. MLP (R2 test = 0.950, MRE (%) = 11, rRMSE = 2.3 %) and XGBR (R2 test = 0.909, MRE (%) = 2.2, rRMSE = 2.9 %) model a good estimation of Nu. XGBR (R2 test = 0.999, MRE (%) = 1.2, rRMSE = 1.6 %) also estimates pressure drop with good accuracy. KFold cross validation was employed to evaluate the mean CV score of the developed model.

Optimization of Pin Fins Using Computational Fluid Dynamics and Machine Learning

This paper presents a two-part study focusing on the optimization of pin-fin arrays for gas turbine blade cooling. The first part of the study examines the thermal performance of various pin-fin shapes and sizes using computational fluid dynamics. The study investigates circular, elliptical, hexagonal, and rectangular cross sections, with emphasis on the hydraulic diameter and Reynolds number. Two-dimensional simulations mimicked a confined, staggered array of uniform-sized pins under different inlet conditions. For a hydraulic diameter of 0.053 m and a Reynolds number of 5500, the rectangular pins showed the highest Nusselt number 8.98, 16.01, and 20.62% larger than circular, elliptical, and hexagonal pins, respectively, but also a pressure increase 68.30% higher on average. For a hydraulic diameter of 0.046 m and a Reynolds number of 1000–15,000, it was shown that all shapes have an exponential increase in pressure and a logarithmic decay in the Nusselt number. Standing out was the rectangular shape, which, at a maximum Reynolds number of 15,000, had a pressure increase of 108% larger than the next in line, the hexagonal pin. In the same range of inlet conditions, the Gee–Webb coefficient was the highest for the circular pin, which was selected as the main shape for the following segment. In the second part of the study, a machine learning framework based on a neural network architecture is presented. The neural network predicts the thermal performance of different pin-fin array configurations. At the end, this framework is used in an optimization process that explores the advantages of nonuniform arrays consisting of differently sized circular pins as opposed to the standard uniform structures of the first part. The model proves to be capable of accurately predicting the characteristic thermal performance coefficients across a wide range of input parameters. The nonuniform array managed a 23% reduction in pressure rise at a 0.2% exit temperature increase compared to a reference standard array of the same hydraulic diameter.

Experimental investigation of the thermal-hydraulic characteristics of liquid cooling heat sinks with novel pin fins

Pin-fin heat sinks (PFHSs) in single-phase liquid cooling systems possess significant potential for extracting higher levels of heat from avionics. However, there is a scarcity of investigations on PFHSs with innovative pin fin shapes. Here, petaloid I and II, pinwheel-like, and honeycombed shapes were designed, and their thermal-hydraulic characteristics were examined under inlet temperatures of 10 and 20 °C, flow rates of 400–2000 mL/min, and heat fluxes of 60–150 kW/m2. Among these PFHSs, the honeycombed shape exhibited the highest heat transfer coefficient, followed by the pinwheel-like shape; they also displayed the lowest wall temperature. However, their Nusselt numbers were lower than those of petaloid heat sink I. The Nusselt number of each heat sink exhibited a downward trend with the increasing inlet temperature and heat flux, while the friction factor remained largely unaffected. The performances were evaluated by a comprehensive factor, and the honeycombed PFHS ranked first. New correlations for the Nusselt number and friction factor of these PFHSs were developed. The mean absolute deviations were all less than 5%, with most predicted values falling within the ±5% range compared to experimental values. These novel heat sinks are crucial for enhancing the performance of airborne liquid cooling systems.

Enhancing solar panel cooling efficiency: a study on the influence of nanofluid inclusion and pin fin shape during melting and freezing of phase change materials

The present article presents a 3D simulation of a solar thermal panel containing phase change materials (PCMs). Two pipes are devised in the panel, and several pin fins (PFs) are applied to each pipe. Organic PCMs are encapsulated in a compartment around the PFs and pipes. The variable is PF shape, which includes four types, i.e., square, rectangular, triangular, and circular. Nanofluid (NFD) is used within the pipes. The study is carried out transiently and continued until the stabilization of outlets. Utilizing an FEM method based on a weak form, namely, Galerkin, to find a numerical solution for mathematical modeling. The artificial intelligent results indicate that using triangular, square, rectangular, and circular PFs provides the highest NFD temperature in the outlet, respectively. Circular PFs lead to a lower heat transfer coefficient (HC) compared to other PFs. The comparison between various PF shapes shows that the use of circular and triangular PFs results in the lowest and highest panel temperature, respectively. Moreover, the highest and lowest volume fraction of melting PCMs around the pipe is obtained through the use of triangular and circular PFs, respectively.

Design and Optimization of Heat Sinks for the Liquid Cooling of Electronics with Multiple Heat Sources: A Literature Review

This paper presents a detailed literature review on the thermal management issue faced by electronic devices, particularly concerning uneven heating and overheating problems. Special focus is given to the design and structural optimization of heat sinks for efficient single-phase liquid cooling. Firstly, the paper highlights the common presence and detrimental consequences of electronics overheating resulting from multiple heat sources, supported by various illustrative examples. Subsequently, the emphasis is placed on single-phase liquid cooling as one of the effective thermal management technologies for power electronics, as well as on the enhancement of heat transfer in micro/mini channel heat sinks. Various studies on the design and structural optimization of heat sinks are then analyzed and categorized into five main areas: (1) optimization of channel cross-section shape, (2) optimization of channel flow passage, (3) flow distribution optimization for parallel straight channel heat sinks, (4) optimization of pin-fin shape and arrangement, and (5) topology optimization of global flow configuration. After presenting a broad and complete overview of the state of the art, the paper concludes with a critical analysis of the methods and results from the literature and highlights the research perspectives and challenges in the field. It is shown that the issue of uneven and overheating caused by multiple heat sources, which is commonly observed in modern electronics, has received less attention in the literature compared to uniform or single-peak heating. While several design and structural optimization techniques have been implemented to enhance the cooling performance of heat sinks, topology optimization has experienced significant advancements in recent years and appears to be the most promising technology due to its highest degree of freedom to treat the uneven heating problem. This paper can serve as an essential reference contributing to the development of liquid-cooling heat sinks for efficient thermal management of electronics.

Study on flow and heat transfer characteristics in rectangular channels with lantern-shaped pin fin array: Part II—Global sensitivity analysis and optimization

Increasing gas turbine inlet temperatures are placing more stringent requirements on the efficiency of internal cooling. Pin fin arrays are a common tool for cooling electronic components or trailing edge cooling channels of gas turbine blades. A crucial concern for researchers is how to achieve a higher Nusselt number with constrained pressure loss to guarantee that the efficiency of the gas turbine will not be impacted by the power dissipation generated by the driving flow passing through the internal cooling loops. In Part I of this study, a lantern-shaped pin is proposed. To seek a more efficient design solution for the pin fin shape, the second part combines the surrogate model, Sobol’s method, and NSGA-II optimization method to perform the overall and spatial sensitivity analysis and optimization for the shape variables on the generatrix of different pin rows. The first-order and total-order sensitivity indices of different variables to Nu T and f are calculated using the surrogate model-based Sobol’s method. The variables that significantly affect the channel performance are identified. The overall and spatial sensitivity analysis results indicate that the variable X 3 i -1 contributes the most to Nu T and f, with total-order sensitivity indices of 70.59–64.26 and 58.16–59.09%, respectively. The overall optimization increases the Nu T and f by 6.95 and 9.91%, respectively, while the spatial optimization leads to an increase in the Nu T by 2.29% and a decrease in the f by 4.56%. Correspondingly, the two optimizations resulted in an increase in the TPI by 3.61 and 3.89%, respectively. The Pareto front solution obtained by the spatial optimization has a more concentrated distribution. Although the TPI obtained by the spatial optimization is only 0.21% higher than that of the overall optimization, it provides designers with a strategy considering the Nusselt number and pressure loss.

Numerical analysis of the magnetic field impact on hydrothermal characteristics of a microchannel heatsink with Fe3O4 ferrofluid and various pin-fin shapes

Enhancing the hydrothermal proficiency of thermal management devices by integrating active and passive heat transfer techniques is possible. Under magnetic field (MF), pin–fin heat sinks have rarely been studied in terms of frictional losses and coefficient of heat transfer (h). Here, with a nanoparticle concentration ratio of 2%, Fe3O4 ferrofluid flow inside a pin–fin heatsink was analyzed numerically considering various pin–fin shapes (rhumbas, squares, circles, and triangles) for absenteeism (WO) and attendance (W) of MF. In the results, the greatest and lowest gains for h were 13.12% and 8.8%, respectively, utilizing MF and Re = 200, for the circular and triangular heatsinks, which would be reduced to 5.36% and 2.41% by increasing Re to 500. In addition, h (and thermal resistance factor) in triangular configuration is 7.82–10.86% (and 4.98–8.68%) and 3.23–8.08% (1.94–6.22%) greater (and smaller) than that in the circular design under two scenarios of MF. Moreover, MF brings about a reduction of 1.86–0.60%, 1.61–0.46%, 1.71–0.54%, and 1.16–0.24% in Tm,CPU for the circular, square, rhumbas, and triangular configurations, respectively, within the Re range of 200–500. Although, when MF is present, pressure loss escalates by almost 6.39%, 4.97%, 3.60%, and 2.92% at Re numbers of 200, 300, 400, and 500 for each configuration, with the maximum pressure loss for triangular heatsink compared to the other arrangements. PEC factors at different Re numbers range from 1.51 to 1.87, suggesting an improved heatsink hydrothermal performance under MF impact compared to absenteeism of that. The highest/lowest PEC values at Re numbers 200 and 500 are associated with the rhumbas/triangular (1.871/1.782) and Triangular/square (1.547/1.496) configurations, respectively.

Using artificial intelligence and two-phase numerical simulation method for investigating the effect of the shape of pin fins on the entropy production of nanofluid flow in a heatsink at different flow rates

Numerical simulations of a heatsink (HTK) are performed in this article for cooling a heat source with multiple pin-fins (PFS). The HTK is placed in a channel with alumina/water nanofluid flow. The two-phase nanofluid is simulated using the finite element method (FEM). Artificial intelligence is also utilized for data analysis. The results of this study demonstrate that the enhancement of Re from 200 to 600 reduces the maximum temperature (T-mx) in the square and rhombus PFS by 6.8% and 7%, respectively. The increase of Re from 200 to 600 decreases the average temperature (T-av) of the HTK by 6.8% and 6.9% for square and rhombic PFS, respectively. An increment in Re diminishes the outlet temperature (T-ot) for both pin-fin shapes. As Re is enhanced, the amount of Δp is intensified. The use of square PFS results in more values of Δp in the HTK compared to the rhombus ones. A maximum enhancement in Δp, i.e. 17.9%, corresponds to Re = 600. The square shape of PFS generates more thermal, frictional, and total entropy than the rhombic shape of PFS. The increase of Re reduces the thermal ENG and enhances the frictional and total ENG for both shapes of PFS.

Three-dimensional Lattice Boltzmann study on structure optimization and heat dissipation performance of pin-fin heat sink integrated with phase change material

Phase change material (PCM) cooling is an excellent approach for reducing the excessive temperature of electronic devices. However, the heat transfer capacity of a heat sink is diminished by the low thermal conductivity of a PCM. Although this issue can be ameliorated by using extended pin-fins and nanoparticles, the latent heat storage capability of a PCM is decreased. To optimize the heat transfer efficiency of PCM heat sink with pin-fins, in this study, the effects of pin-fin shapes (circle, triangle, square, pentagon, hexagon, and octagon), novel arrangements with triangular fins, and the volume fraction of nanoparticles are investigated using the 3D enthalpy-based multi-relaxation time lattice Boltzmann method. The results showed that the PCM heat sink with triangular pin-fins exhibited optimal thermal performance due to the largest heat transmission area between the PCM and pin-fins. After conducting optimization research on triangular pin-fin arrangements, the full melt time was shortened by 14.3 % and the heat dissipation power was increased by up to 15.2 %, when compared with the PCM heat sink with triangular pin-fins. Furthermore, nanoparticles with a volume fraction of <0.1 were beneficial for balancing the elevated heat dissipation capacity and reducing the latent heat duration of the nano-enhanced PCM.

The entropy generation analysis of a pin–fin heatsink with Fe3O4 ferrofluid coolant and considering four different pin–fin shapes (circular, square, rhumbas, and triangular) in the presence of the magnetic field

The entropy generation analysis was performed to determine the viscose and thermal irreversibilities (Ṡfr and Ṡth) inside a pin–fin heatsink under the absence (WO) and presence (W) of the magnetic field considering Res of 200, 300, 400, and 500, four different pin–fin shapes, and Fe3O4 ferrofluid coolant. The results demonstrated that Ṡfr and Ṡth escalates and diminishes, respectively, by increasing Re or by applying the magnetic field effects. For instance, the increase in Re from 200 to 500 escalates Ṡfr by 86% and 80% for 4 configurations and under WO and W scenarios of the magnetic field. Besides, the highest Ṡfr (and lowest Ṡth) was observed for the triangular configuration, which is nearly 12.79% (and 8.36%) and 13.89% (and 11.18%) higher than that for the circular configurations with the lowest Ṡfr (and highest Ṡth) among four configurations at Re = 200. Furthermore, the magnetic field escalates Ṡfr by 41.88%, 37.19%, 37.49%, and 34.06% over the base case without the magnetic field for circular, square, rhumbas, and triangular heatsinks, respectively, at Re = 200. These values diminish to 10.50%, 11.46%, 10.51%, and 7.77% as Re increases from 200 to 500. In addition, Ṡth decreases by 21.98% (or 7.39%), 19.18% (or 6.17%), 20.95% (or 7.15%), and 14.00% (or 3.46%) under the W scenario against the WO scenario for circular, square, rhumbas, and triangular configurations, respectively, at Re of 200 (or 500).

Numerical study of heat transfer enhancement over a rotating surface. Part I: Effect of pin-fin shapes

Rotating machinery like gas turbine engines consist of rotating components like gas turbine disks that are exposed to high thermal loads and stresses due to centrifugal force acting on them, and thus effective cooling is essential. The disks are additionally exposed to hot turbine gas ingress as an adverse pressure gradient is created in the stator-rotor cavity due to outward pumping of near-disk flow. Impingement of a coolant jet on such a surface can effectively provide cooling and also counter this adverse gradient. There also exists a circular relative velocity between the disk and wall-jet formed by impinging air as well as the air in the disk vicinity. Thus, the study of heat transfer under rotating conditions becomes important. With the advent of advanced manufacturing techniques, it is possible to produce disks with novel heat transfer enhancement features such as pin-fins which have not been previously explored. They create unique flow features in addition to increasing the surface area. The present study numerically investigates the heat transfer over rotating surfaces under jet impingement with square, triangular, cylindrical and dome-shaped pin-fins. This will inform the optimization of pin geometry for better heat transfer effectiveness and uniformity. Three different jet Reynolds numbers between 5000 and 18000 based on the jet diameter have been studied for three different Rotational Reynolds numbers based on the disk diameter. Transient non-conjugate heat transfer analysis was conducted, and the technique was compared with experimental results on square pin-fins and a smooth circular disk. The heat transfer enhancement greatly depends on the flow separation and pin area normal to the flow. A heat transfer enhancement of close to 2.2 was observed for triangular fins for the lowest rotation speed, for the highest rotation speed, the highest enhancement of close to 1.7 was observed in the cylindrical pins.

Effect of Dimples/Protrusion Concavity on Heat Transfer Performance of Rotating Channel

The continuing increase in gas turbine inlet temperature requires additional heat transfer at the trailing edge. Therefore, a large amount of research has been carried out to find a highly efficient cooling process for gas turbine blades. Pin-fins have been widely used in the trailing edge of gas turbines to enhance heat transfer performance. Pin-fins also strengthen the structure between the inlet and outlet faces of the gas turbine. According to previous research, the flow structure and heat transfer characteristics are influenced by many parameters of the pin-fin array, especially the pin-fin shape, height, diameter as well as layout. In this study, instead of changing the structure of the pin-fin array, the work focused on the design of protrusion/dimple points on the leading and trailing edges. Numerical simulations using the SST (Shear Stress Transport) turbulence model were performed to investigate the effect of dimple/protrusion concavity on flow structure and heat transfer characteristics in a rotating channel with pin-fin array. The pin-fins are arranged staggered to each other. The results show that when changing the dimple/protrusion concavity on the leading and trailing edges combined with the rotation speed, the heat transfer efficiency changes positively.

Numerical simulation of heat transfer of two-phase flow in mini-channel heat sink and investigation the effect of pin-fin shape on flow maldistribution

Nowadays, given the rising power of processors and the increase in operating temperature of these objects, the cooling and heat loss process is necessary to prevent the breakdown of these devices. Considering the ability to dissipate high heat flux in mini-channels and low pressure drop, in this study, the performance of mini-channels with different inlet headers was studied. Accordingly, 3 pin fins with elliptical, circular and V-shaped cross-sections in the inlet header were examined in terms of velocity distribution uniformity and heat sink surface temperature reduction. The lowest maldistribution and surface temperature were obtained for the header with elliptical pin fins having a diameter ratio of a/b = 2. Also, the effect of employing the nanofluid in mini-channel on pressure drop and heat transfer was investigated by utilizing the two-phase mixture model. The results showed that with the rise of volume fraction (∅) and Reynolds number (Re), thermal resistance was reduced significantly. Also, the highest Nusselt number (Nu) with the Re of 3000 and volume fraction of 0.5% was obtained to be equal to 77.3.

Study on the Heat Dissipation Performance of a Liquid Cooling Battery Pack with Different Pin-Fins

The heat dissipation capability of the battery thermal management system (BTMS) is a prerequisite for the safe and normal work of the battery. Currently, many researchers have designed and studied the structure of BTMS to better control the battery temperature in a specific range and to obtain better temperature uniformity. This allows the battery to work safely and efficiently while extending its life. As a result, BTMS has been a hot topic of research. This work investigates the impact of pin-fins on the heat dissipation capability of the BTMS using the computational fluid dynamics (CFD) approach, designs several BTMS schemes with different pin-fin structures, simulates all schemes for fluid-structure interaction, and examines the impact of different distribution, number, and shape of pin-fins on heat dissipation capability and pressure drop. Analyzing the effect of cooling plates with different pin-fins on the thermal capability of the BTMS can provide a basis for the structural design of this BTMS with pin-fin cooling plates. The findings demonstrate that the distribution and quantity of pin-fin shapes might affect heat dissipation. The square-section pin-fins offer better heat dissipation than other pin-fin shapes. As the pin-fins number increases, the maximum battery temperature decreases, but the pressure drop increases. It has been observed that uniform pin-fin distribution has a superior heat dissipation effect than other pin-fin distribution schemes. In summary, the cooling plate with a uniform distribution of 3 × 6 square section pin-fins has better heat dissipation capability and less power consumption, with a maximum battery temperature of 306.19 K, an average temperature of 304.20 K, a temperature difference of 5.18 K, and a pressure drop of 99.29 Pa.

Shape optimization of pin fin array in a cooling channel using genetic algorithm and machine learning

This article reports the optimization of pin fin shape using a genetic algorithm (GA) coupled either to a machine learning (ML) model or a computational fluid dynamics (CFD) model. The ML model evaluates the temperature and pressure induced by the fins within a second and allows us to replace the time-consuming CFD simulations during the design stage. The optimization is conducted for a cooling channel with a uniform heat flux boundary condition (5 W/cm2) in the Reynolds numbers range of 3000 – 12000. The optimization identifies a funnel-shaped fin that enhances the heat transfer coefficient by 20% without an apparent increase of pressure drop as compared to the standard cylindrical pin fins. The funnel-shaped fin outperforms other conventional fins of elliptical, cubic, and drop shapes that induce a similar level of pressure drops. This work demonstrates the potential of ML-based optimization in searching unexplored shapes of heat transfer systems with superior performance.

Impacts of Pin Fin Shape and Spacing on Heat Transfer and Pressure Losses

Abstract Additive manufacturing (AM) provides designers with the freedom to implement many designs that previously would have been costly or difficult to traditionally manufacture. This experimental study leverages this freedom and evaluates several different pin shapes integrated into pin fin arrays of a variety of spacings. Test coupons were manufactured out of Hastelloy-X using direct metal laser sintering and manufacturer-recommended process parameters. After manufacturing, internal surface roughness and as-built accuracy were quantified using Computed Tomography (CT) scans. Results indicated that pin fins were all moderately undersized, and there was significant surface roughness on all interior surfaces. Experimental data indicated that diamond-shaped pins were found to have the highest heat transfer of the tested shapes, but triangle-shaped pins pointed into the flow incurred the smallest pressure drop. Modifications to the streamwise spacing of the pins had little impact on the friction factor, but did increase heat transfer with increasing pin density. Prior Nusselt number correlations found in literature underestimated heat transfer and pressure loss relative to what was measured resulting from the AM roughness. A new correlation was developed accounting for AM roughness on pin fin arrays.