Shear Stress Transport Turbulence Model Research Articles

Data assimilation method and application of shear stress transport turbulence model for complex separation of internal shock boundary layer flow

Data assimilation method and application of shear stress transport turbulence model for complex separation of internal shock boundary layer flow

A modification of production term for the shear stress transport turbulence model based on a new wall-law for adverse pressure gradient

This paper presents an attempt to improve the predictive accuracy of the Menter shear stress transport (SST) turbulence model for adverse pressure gradient (APG) flows. The foundation of this work lies in the newly modified law of the wall and turbulent kinetic energy (TKE) transport equation within the APG turbulent boundary layer. The modification of the law of the wall is achieved through a newly proposed variable λ, which is derived theoretically and calibrated using direct numerical simulation data. Based on the new law of the wall, we analyze the TKE transport equation of the SST model at APG and demonstrate that the analytical solution satisfying the law of the wall cannot achieve equilibrium in the current SST model. Further theoretical analysis reveals that this imbalance is caused by the TKE production term Pk, and the decomposition of the wall friction coefficient Cf indicates that Pk directly affects the prediction of flow separation. Based on the analysis and the new law of the wall, an additional term for Pk is suggested to correct Pk and improve the model's predictive accuracy for APG flows. Numerical validation results show that the correction leads to an increase in Pk within the APG turbulent boundary layer, resulting in more accurate predictions of Cf and the mean velocity profile in the inner layer of the turbulent boundary layer.

A multi-physics correction of the shear-stress transport turbulence model for supersonic flows

Though the k–ω shear-stress transport (SST) turbulence model is widely used, it is developed based on incompressible flow and the analysis of simple flow characteristics such as boundary layer and free shear flows. Due to the lack of comprehensive consideration of important flow structures, such as shock wave and highly compressible zones, the k–ω SST turbulence model has inherent limitations in describing supersonic flows. A multi-physics improvement strategy is proposed to improve the prediction accuracy of the k–ω SST model for supersonic flows. This strategy leverages shock/turbulent boundary layer and shock/compressibility functions to accurately recognize areas with significant structures, enabling targeted improvement of the turbulence model. Five supersonic flow cases are tested and analyzed, and the results show that while the single-physics turbulence model can improve the prediction accuracy of flows with a single flow structure corresponding to the correction, its prediction ability is insufficient in other flows with different flow structures. In contrast, the multi-physics turbulence model exhibits good ability in flows with multiple flow structures, while also maintaining the performance of the single-physics turbulence model. The multi-physics turbulence model has higher accuracy and stronger universality, making it advantageous for modeling complex supersonic flows.

Numerical simulation of dynamic layer freeze desalination within an indirect contact freeze crystallizer

In the current study, a dynamic layer freeze desalination system is simulated numerically. The computational domain is a two-dimensional rectangular channel which contains inlet and outlet flows, and the simulation is performed using computational fluid dynamics. A pre-concentrated mixture is considered as the feed solution with an initial temperature and concentration of 257 K and 0.2 kg/kg, respectively. In this work, since the simulation parameters such as temperature and species mass fraction have high importance across the entire domain, the k–ω shear stress transport turbulence model was selected. A parametric study on the effect of the heat flux of the cold wall on the ice salinity and desalination rate is performed using three cases with heat fluxes of −1000, −1500, and −3000 Wm−2. It is observed that the ice generation speed in the case with a heat flux of −3000 Wm−2 is 3.28 times greater compared to the case with −1000 Wm−2 and its desalination rate is only 2.59% lower. The effect of the inlet velocity on the mentioned parameters is also investigated. It is observed that the cases with turbulent flow have approximately 19% and 23% lower ice salinity compared to the case with laminar flow.

Vortex-induced vibration effect on the aeroelastic stability of two composite cylindrical shells using a fluid-structure interaction method

The purpose of this study, is to investigate the aeroelastic stability and effect of vortices resulting from passing air over cylindrical shells in three-dimensional condition. Here, the Naiver-Stokes equations in the integral form are considered studying the air flow based on the finite-volume method. The ANSYS Fluent software is used to study the fluid-solid interaction effect. The shear stress transport (SST) turbulence model is utilized to simulate the turbulent viscosity. Effect of different parameters such as two cylindrical shells alignment or two cylinders diameter ratio are considered. The results indicate that the vortices can play a significant role on the aeroelastic stability of the cylindrical shell.

CFD Simulations and Phenomenological Modelling of Aerodynamic Stall Hysteresis of NACA 0018 Wing

Computational simulations of three-dimensional flow around a NACA 0018 wing with an aspect ratio of AR=5 were carried out by using the Unsteady Reynolds-Averaged Navier–Stokes (URANS) equations with the Shear-Stress Transport turbulence model closure. Simulations were performed to capture aerodynamic stall hysteresis by using the developed pseudo-transient continuation (PTC) method based on a dual-time step approach in CFD OpenFOAM code. The flow was characterized by incompressible Mach number M=0.12 and moderate Reynolds number Re=0.67×106. The results obtained indicate the presence of noticeable aerodynamic hysteresis in the static dependencies of the force and moment coefficients, as well as the manifestation of bi-stable flow separation patterns, accompanied by the development of asymmetry in the stall zone. The URANS simulation results are in good agreement with the experimental data obtained for the NACA 0018 finite-aspect-ratio wing in the low-speed wind tunnel under the same test conditions. A new phenomenological bifurcation model of aerodynamic stall hysteresis under static and dynamic conditions is formulated and is proven to be able to closely match the experimental data.

Experimental investigations on cooling characteristics of different trailing-edge cutback geometries

One important method for enhancing the performance of modern engines is to increase the turbine inlet temperature. Due to the high velocity near the throat, the heat transfer to the blade trailing edge is high, particularly on the pressure side near the trailing edge. Therefore, the design methodology for cooling structures becomes critical for the thinner trailing edge compared to other parts of the blade. Trailing-edge cutback is a common cooling structure that guides cold air to form an effective film near the blade pressure side. However, the cutback lip induces strong and unsteady shedding vortexes, which significantly reduce the downstream coolant effectiveness.Previous studies have explored the film cooling performances of cutback structures and the interaction between coolant and mainstream using experimental and numerical methods. Experimental results were obtained using Pressure-Sensitive Paint (PSP) and Particle Image Velocimetry (PIV) in a large-scale wind tunnel, while the Delayed Detached Eddy Simulation (DDES) with the Shear Stress Transport (SST) turbulence model was employed for capturing the unsteady flow field.In this paper, further investigation will be conducted on the lip profiles of the fillet structure to improve the effectiveness of the film coolant. The rounded lip design delays boundary layer separation, thereby reducing the scale and intensity of shedding vortices. This improvement in the effectiveness of the rounded lip nozzle model is observed across all blowing ratios. Furthermore, at low or medium blowing ratios, the rounded lip design significantly reduces momentum exchange, inhibiting the mixing between the mainstream flow and cooling air. This leads to a more pronounced enhancement in cooling effectiveness.

Simulation research on aerodynamic noise characteristics of a compressor under different working conditions.

The shear stress transport turbulence model is employed to conduct a detailed study of flow characteristics at the highest efficiency point and near-stall point in a full-channel 1.5-stage compressor in this paper. The simulation results for the compressor's total pressure ratio and efficiency exhibit good agreement with experimental data. Emphasis is placed on examining the internal flow structure in the tip area of the compressor rotor under near-stall conditions. The results reveal that significant differences in flow structure primarily occur in the tip area as the compressor approaches stall. Specifically, a reduction in turbulent kinetic energy is observed in a region spanning approximately 20%-60% of the chord length on the rotor suction face near-stall conditions. Two additional peak frequencies, at 0.8 and 1.6 times the blade passage frequency, are observed, and the intricate flow phenomena are elaborated at the near-stall point. The near-stall point exhibits greater noise levels than the highest efficiency point, where the intensity of the surface source increases by more than 10 dB, peaking at 20 dB. This additional peak serves as a significant supplementary noise source near the stall point, leading to a maximum increase of 33.3 dB in the free radiated sound power. The acoustic response within the duct indicates that the compressor operating at the near-stall point continues to produce substantial noise on the actual test bench, showing an average increase of 6 dB in noise levels, and the distribution of the additional peak single-tone noise at the entrance significantly differs from that observed at the highest efficiency point.

Implementation of a PAFV turbulence model for airfoil flow simulation on OpenFOAM

To further develop a more effective turbulence model and to improve the calculation accuracy of the flow around airfoil, a new PAFV turbulence model has here been constructed by using a deformation rate tensor and the grouping of an average fluctuation velocity. To evaluate the applicability of the PAFV turbulence model, the numerical calculations of flow around the airfoil have here been implemented, which was based on the OpenFOAM calculation platform. On the basis of grid independence research, the model was used to calculate the low-speed flow-around problem for the plano-convex airfoil NACA4412 and the symmetric airfoil NACA0012. It was also compared with the S-A (Spalart-Allmaras) and SST (Shear Stress Transport) k-ω turbulence models. Firstly, the maximum lift angle-of-attack case of the NACA4412 airfoil was calculated. Thereafter, numerical calculations were performed for the flow around the airfoil in the multi-angle-of-attack case of the NACA0012 airfoil. The results showed that the NACA4412 airfoil had an obviously separated vortex at the trailing edge of the airfoil at the maximum lift angle of attack. Also, there was a certain velocity loss downstream of the trailing edge, which was calculated by all three models. However, the results of the PAFV turbulence model were found to be better than those of the S-A and SST turbulence models. The three turbulence models showed comparable accuracies for the calculations of the surface pressure coefficients of the NACA0012 airfoil. However, the S-A and SST k-ω turbulence models were slightly better for the calculations of the mean velocity profiles of the NACA0012 airfoil. Also, the PAFV turbulence model was more accurate for the calculations of the lift and drag coefficients. In conclusion, the PAFV model can make effective predictions of the airfoil low-speed flow around the problem at hand, which in turn preliminarily verifies the applicability of this turbulence model for the low-speed flow around the airfoil problems.

Numerical and experimental study of the impact on aerodynamic characteristics of the NACA0012 airfoil

Abstract Using computational models and low-speed wind tunnel tests, the aerodynamic characteristics of the NACA 0012 airfoil with low Re numbers of (8 × 10 4 {10}^{4} , 2 × 10 5 {10}^{5} , 3 × 10 5 {10}^{5} , and 4 × 10 5 ) {10}^{5}) and angle of attack (AOA) ranging from 0° to 18° by two steps are examined. Using the same 3-D wind tunnel dimensions, numerical simulations were run. The software program ANSYS FLUENT was used to solve the mathematical model using the continuity equation, the Navier‒Stokes equations, and the k–ω shear‒stress transport turbulence model. Findings demonstrate that at all AOAs, there is a direct relationship between Reynolds numbers (Re), lift and drag coefficients, kinetic energy, and stall angle. The lift coefficient rises linearly as the AOA increases, peaking at 14°, the stall angle at higher Reynolds number. The lift coefficient was found to decline when the AOA was increased further, reaching its minimal value at an AOA of 18°. With a greater AOA, the airfoil’s drag coefficient rises, creating turbulent flow. The eddies produced by the turbulence cause the flow to start separating from the airfoil surface as turbulence increases. As a result, the airfoil lift coefficient drops, and its drag coefficient rises at the same time, leading to poor performance. The validation of the numerical results through wind tunnel experiments provided confidence in the findings of the study.

Numerical modelling and experimental validation of dripping, jetting and whipping modes of gas dynamic virtual nozzle

PurposeThis study aims to develop an experimentally validated three-dimensional numerical model for predicting different flow patterns produced with a gas dynamic virtual nozzle (GDVN).Design/methodology/approachThe physical model is posed in the mixture formulation and copes with the unsteady, incompressible, isothermal, Newtonian, low turbulent two-phase flow. The computational fluid dynamics numerical solution is based on the half-space finite volume discretisation. The geo-reconstruct volume-of-fluid scheme tracks the interphase boundary between the gas and the liquid. To ensure numerical stability in the transition regime and adequately account for turbulent behaviour, the k-ω shear stress transport turbulence model is used. The model is validated by comparison with the experimental measurements on a vertical, downward-positioned GDVN configuration. Three different combinations of air and water volumetric flow rates have been solved numerically in the range of Reynolds numbers for airflow 1,009–2,596 and water 61–133, respectively, at Weber numbers 1.2–6.2.FindingsThe half-space symmetry allows the numerical reconstruction of the dripping, jetting and indication of the whipping mode. The kinetic energy transfer from the gas to the liquid is analysed, and locations with locally increased gas kinetic energy are observed. The calculated jet shapes reasonably well match the experimentally obtained high-speed camera videos.Practical implicationsThe model is used for the virtual studies of new GDVN nozzle designs and optimisation of their operation.Originality/valueTo the best of the authors’ knowledge, the developed model numerically reconstructs all three GDVN flow regimes for the first time.

VALIDATION OF THE HYDRAULIC TURBINE OPENFOAM LIBRARY FOR A HIGH-PRESSURE CENTRIFUGAL COMPRESSOR

A special program module was added to OpenFoam more than 10 years ago, and a large number of studies have been devoted to its use for solving turbine engineering problems. Modeling inaccuracies can occur when the velocity is increased to supersonic flow. The aim of this work is to validate the OpenFoam open library of hydraulic turbines for the a high-pressure centrifugal compressor flow calculation and finding the parameters and calculation model that are optimal in terms of efficiency and total/total pressure ratio. For the numerical calculation, we used Reynolds averaging of the Navier-Stokes equations, which are used in the CFD library OpenFoam v. 2212. In this work, the two most commonly used turbulence models for such problems are used to close the equations of the mathematical model: the k-e model and the Shear stress transport (SST) model. The simulation was performed using a modified version of the sonicFoam solver, which is available in OpenFoam. The maximum error in calculating the total pressure ratio in the working zone for all models was 3 %. All models behave poorly in the low mass flow rate zone. The slope of all curves corresponds to the experimental characteristic. The calculation using the models with very fine meshes on average determines a 2 % increase in the total-to-total pressure ratio. Using OpenFoam, the integrated parameters of a high-pressure centrifugal compressor can be predicted accurately (maximum error does not exceed 5 %). The most accurate efficiency is predicted by the SST model using meshes of more than 2.56 million elements, but this number of elements is not enough to predict the compressor's performance at low flow rate zone. In further research, it is rational to use grids consisting of at least 5 million elements and use the SST turbulence model.

Heat recovery optimization of a shell and tube bundle heat exchanger with continuous helical baffles for air ventilation systems

We report a numerical evaluation of the impact of continuous helical baffle on the heat recovery efficiency of counterflow tube bundle heat exchangers. The baffle inclination angle has been varied from 11∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$11^{\\circ }$$\\end{document} to 22∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$22^{\\circ }$$\\end{document}. Since the fluid flows over the tube bundle at an angle due to helical flow inside the shell, the heat exchanger operates in cross counter mode. Fluent simulations with the k-ω\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\omega$$\\end{document} transition shear stress transport turbulence model have been performed to investigate the thermal-hydraulic parameters of the system in terms of heat recovery efficiency, pressure loss, and overall heat transfer rate. Outside air temperature has been varied to mimic cold and warm weather. Pressure loss has been constrained to be less than 250 Pa, conforming to EU guidelines for energy labeling of residential ventilation units. At the maximum volume flow rate of 40 m3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^3$$\\end{document}/h, the device performed with over 80%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$80\\%$$\\end{document} heat recovery efficiency for the considered temperature difference. Continuous helical baffles helped to improve convective heat transfer by reducing cross flow area and increasing velocity. Smaller angles result in greater pressure loss while having no discernible effect on heat recovery efficiency for the considered geometry. The analysis demonstrates the potential of a compact counterflowing recuperative heat exchanger with continuous helical baffles for decentralized ventilation systems and serves as a basis for further optimization.

Copula-based Bayesian uncertainty quantification framework of SST turbulence model for flow over a Gaussian bump

Quantitatively analyze the uncertainties in turbulence models is of great meaning for research and engineering. In this paper, we develop a Bayesian uncertainty analysis framework based on copulas. The proposed framework is applied to the parametric uncertainty quantification and calibration of the shear-stress transport turbulence model for the flow over a Gaussian bump. A copula function is used to establish the correlation between variables and construct the weight function, which enables greater consideration of Bayesian inference. Prior analysis is conducted based on Sobol indices with the nonintrusive polynomial chaos method, demonstrating the important effects of κ, a1, and β∗ on the flow, both for the wall force coefficients and the Reynolds shear stress. Next, the wall force coefficients and Reynolds shear stress are used as training sets to verify the effectiveness of the method. The results show that modeling the relationship based on copulas is necessary and effective, and that the weight function adaptively balances the influence of physical quantities at different inference locations. The proposed method effectively corrects the computational deviations of the corresponding physical quantities. In addition, the confidence interval for the posterior sample is increased, enhancing the likelihood of obtaining results close to the actual values.

Multifidelity aerodynamic shape optimization for airfoil dynamic stall mitigation using manifold mapping

Aerodynamic shape optimization for dynamic stall mitigation is computationally challenging, requiring multiple costly CFD evaluations. This work proposes a multifidelity modeling technique to efficiently mitigate dynamic stall over an airfoil, particularly manifold mapping (MM) within a trust-region-based optimization framework to find an optimal shape defined by six PARSEC parameters. The high-fidelity (HF) responses are modeled using the unsteady Reynolds-averaged Navier–Stokes equations with Menter’s shear stress transport turbulence model at a Reynolds number of 135,000, Mach number of 0.1, and reduced frequency of 0.05. The low-fidelity responses are acquired from the Kriging regression (KR) trained over the design space. The MM with the pattern-search algorithm is utilized to find optimal designs in two different test cases. The result yields two distinct optimal shapes with a higher thickness, larger leading-edge radius, and more aft camber than the baseline airfoil (NACA 0012), indicating the presence of multiple valid designs. Both designs delay the dynamic stall angle over 3 deg while mitigating peak lift and pitching moment magnitudes. The current approach delivers a computational saving of over 70% compared to HF-KR and Cokriging regression techniques. These findings present an efficient multifidelity strategy with potential application to other computationally expensive optimization problems.

Heat and drag reduction on the hypersonic nose with a nexus between active and passive control methods

This study aimed to conduct an active, passive, and hybrid control analysis on the hypersonic drag and thermal reduction. To achieve this, the Reynolds-averaged Navier–Stokes equations were utilized, along with the shear-stress transport turbulence model. To this purpose, the total pressure ratio, the diameter of the opposing jet outlet, and the number of aerodisks are considered as variable parameters. By combining the above parameters, six different configurations were created. Configuration 1 includes a spike, one aerodisk, and an opposing root jet. In configurations 2–5, the number of aerodisks increments and there is no opposing root jet. Configuration 6 includes a spike, four aerodisks, and an opposing root jet. After validation and analysis of the grid independency, the effects of opposing root jet pressure in values of 0.1, 0.3, 0.5, and 0.7, the diameter of opposing root jet outlet (2, 4, and 6 mm), and the number of aerodisks (1, 2, 3, and 4) were examined thoroughly. In comparison with the optimal parametric model in configuration 1, which has a 6 mm outlet diameter and a total pressure ratio of 0.7, the parametric model under consideration exhibits reductions of 9.96% in the overall drag coefficient, 15.03% in the peak pressure, and 20.8% in the peak heat flux. However, configuration 6 has a noticeable and significant advantage in terms of stability of flow fluctuations in front of the nose. Therefore, due to the superiority of configuration 6 in terms of the stability of the flow fluctuations in front of the nose, which is an important factor in the stability of the aircraft, this configuration is the best among the configurations analyzed in this article.

Verification of the γ-Reθt Transition Model in OVERFLOW and FUN3D

The findings of the recent AIAA and NATO workshops on transition modeling have underscored the importance of verifying the transition models that are based on Reynolds-averaged Navier–Stokes. To that end, the present work aims to verify the Langtry–Menter (LM2009) transition model coupled with Menter’s shear-stress transport (SST) turbulence model. Specifically, the SST-2003-LM2009 model, as implemented in the OVERFLOW structured overset solver and the FUN3D unstructured solver, is applied to both natural and bypass transition scenarios on a flat plate and to natural and separation-bubble-induced transition on the NLF-0416 airfoil. The Richardson extrapolation method was used to analyze and report the grid convergence of integrated and local load coefficients upstream, within, and downstream of the transition region, based on solutions obtained using the two solvers on identical grids. Reasonable agreement is obtained between the two codes for both global and local surface load coefficients when further refining the workshop mesh series, although with a grid-convergence index for the local friction coefficient that may exceed 1% in certain cases. The study also highlights the solution sensitivity to the choice of turbulence inflow boundary conditions and model options, along with the necessity to unambiguously specify this information for benchmark exercises.

Heat transfer enhancement of supercritical carbon dioxide in eccentrical helical tubes

A type of eccentrical helical tube (EHT) was proposed for more efficient and compact supercritical carbon dioxide (SCO2) heat exchangers in refrigeration systems. The forced convective heat transfer of SCO2 flowing in three designed eccentrical helical tubes with pitches of 25, 50 mm and eccentricities of 0.9, 1.5 mm was simulated by using the three-dimensional steady Reynolds-averaged Navier-Stokes equations, shear stress transport turbulence model and energy equation in ANSYS CFX 2019 R2 at mass fluxes of 200, 400 kg/m2s, inlet pressures of 8, 9 MPa, outwards wall heat fluxes of 12, 24 kW/m2. The flow and heat transfer models were validated in the plain tube with experimental mean heat transfer coefficient and empirical Darcy friction factor. Influences of pitch, eccentricity and operational conditions on heat transfer enhancement were identified. Flow pattern, heat transfer mechanism and vortex kinematics were clarified. Heat transfer enhancement of SCO2 in the EHT was compared with water and air in the EHT, twisted elliptical tube and conical tube, respectively. A pitch of 25 mm and eccentricity of 1.5 mm at 6 mm tube diameter can achieve a better thermal-hydraulic performance. A higher SCO2 mass flux raises Nusselt number and reduces friction factor, a higher inlet pressure and a larger wall heat flux reduces Nusselt number but increases friction factor. The ratio f/f0 is ranged in 2.52–1.68 and drops off with increasing inlet pressure and nominal Reynolds number, the ratios Nu/Nu0, ψ and η curves show a concave shape near the pseudocritical point ranged in 1.68–1.06 and 1.06–1.55, 1.23–0.83 and 0.83–1.30, 0.67–0.50 and 0.50–0.92 at the pitch of 25 mm and eccentricity of 1.5 mm, inlet pressure of 8 MPa, mass flux of 400 kg/m2s, and wall heat flux of 12 kW/m2. A helical flow pattern with a core flow occurs in the EHT, the local heat transfer coefficient can be correlated to absolute helicity. The high-wall shear stress on the ridge of the EHT is responsible for the heat transfer enhancement. The f/f0 value of the EHT is in between the twisted elliptical tube and the conical tube, but the Nu/Nu0 and ψ values are comparable.

Thermal Performance Improvement of a Spiral Channel Solar Air Heater: Numerical and Experimental Investigation in the Desert Climate of Gabes Region

Abstract This study focuses on improving the thermal performance of a solar air heater (SAH) using a single-pass spiral-shaped ducts. The SAH is designed and tested under prevailing weather conditions of Gabes, Tunisia (33°52.8876′ N,10°5.892′ E). The experimental measurements are carried out over 4 days. Similarly, a computational fluid dynamics (CFD) model was developed to study the fluid flow and the heat transfer inside the SAH using the commercial software ansys fluent 2021 R1”. The discrete ordinate (DO) radiation model and the k-ω shear stress transport (SST) turbulence model are used to study the radiative heat transfer and the turbulent flow in the SAH, respectively. The numerical model is validated against experimental data, and the average error does not exceed 3.6%. To improve the heat transfer phenomena, the ratio of horizontal baffle spacing “d” to vertical baffle spacing “p” (d/p) is numerically investigated. Moreover, the highest air outlet temperature during the test days reached 81.1 °C under a mass flowrate of 0.0077 kg/s. The maximum efficiencies are 57%, 54%, 49%, and 46% for the configurations d/p = 1.5, d/p = 2, d/p = 1, and d/p = 0.5 under a mass flowrate of 0.02 kg/s, respectively. The SAH design with d/p = 1.5 is about 4–10% more efficient than the standard design with d/p = 1 under a mass flowrate ranging from 0.0077 kg/s to 0.025 kg/s.

Experiment and Numerical Studies of Convection Heat Transfer around a Rotating Hand-Shaped Former

Forced convective heat transfer around a rotating hand-shaped former was numerically studied to improve the rubber-glove-curing process. The former surface was separated into eight segments for simulation. The shear stress transport turbulence model and its wall functions were employed to model the rotating hand-shaped former in the heated airflow field. The rotation rate of the former varied from 0 to 5 in the freestream. The Reynolds number ranged from 1,583 to 15,837. The simulation results were compared and well agreed with the experimental data. These results indicated that the convective heat transfer of individual sections and the entire body varied according to the aforementioned variables. The most effective rotation rate was observed for the former segments that were far from the rotation axis. The lowest convective heat transfer occurred in the middle finger, which was located on the rotation axis and was shielded by other segments. Therefore, the average Nusselt number on the middle finger was significant and derived using a novel equation. This equation was compared with the computational fluid dynamics results and exhibited an average error and correlation coefficient of 7.32% and 0.9, respectively. It can help reduce the trial-and-error method to obtain curing conditions for rubber glove manufacturing.