Withada Jedsadaratanachai^a, Amnart Boonloi^b,*

Frontiers in Heat and Mass Transfer, Vol.6, pp. 1-19, 2015, DOI:10.5098/hmt.6.13

Abstract Numerical investigations on flow topology, heat transfer behavior and thermal performance evaluation in a circular tube heat exchanger with the punched delta winglet vortex generators (PDWVG) inserted in the middle of the test section are presented. The effects of the flow attack angles that converging to the center of the tube; α = 0°, 5°, 10°, 15°, 20°, 25°, and flow directions; winglet tips pointing downstream and upstream, are investigated for the Reynolds numbers; Re = 100 – 2000. The finite volume method and SIMPLE algorithm are used for the current study. The results are presented… More >

Amnart Boonloi^a, Withada Jedasadaratanachai^b,*

Frontiers in Heat and Mass Transfer, Vol.5, pp. 1-15, 2014, DOI:10.5098/hmt.5.19

Abstract 3D numerical investigations for heat transfer characteristics and flow configurations in a fin–and-oval-tube heat exchanger with V-tip pointing downstream delta winglet pairs (DDWP) are examined. The DDWPs are placed on the fin surface with pointing downstream and the oval tube row number is set at three in a staggered arrangement. The flow attack angles (θ = 15°, 30°, 45° and 60°) and the distance from V-tip to the oval tube center in transverse axis (a = 3.77, 4.77 and 5.77 mm) are investigated for Reynolds number based on hydraulic diameter, Re = 500 – 2500. The numerical results… More >

Amnart Boonloi^*

Frontiers in Heat and Mass Transfer, Vol.5, pp. 1-12, 2014, DOI:10.5098/hmt.5.8

Abstract A mathematical analysis of the heat transfer enhancement, thermal performance and flow configurations in a heat exchanger square duct with diagonal inserted plate vortex generators is presented. The 30o V–shaped baffles are modified and placed on the double sides of the thin plate or frame (with no plate) which inserted diagonally in the square duct. The effects of blockage ratio (b/H, BR), the pitch ratio (p/H, PR), flow direction (V–Downstream and V–Upstream) and configuration of inserting plate are investigated for Reynolds number based on the hydraulic diameter of the square duct, D_h, Re = 100 –… More >

G. Olmi¹

Structural Durability & Health Monitoring, Vol.8, No.1, pp. 61-90, 2012, DOI:10.3970/sdhm.2012.008.061

Abstract Turbogenerator rotors and coil retaining rings are highly loaded components, under low cycle fatigue at every machine switch on and switch off transient. Their failure during service may lead to very serious consequences. The present paper utilizes several experimental data, concerning the static, cyclic and fatigue behaviour of the rotor material, in order to perform a probabilistic analysis. All the main methodological issues are tackled, consisting in the experimental data processing, in the choice of the random variables that are involved in the fatigue process, in the determination of their distributions, in the practical computation More >

Pankaj Saha^a, Gautam Biswas^a,b,*

Frontiers in Heat and Mass Transfer, Vol.2, No.3, pp. 1-5, 2011, DOI:10.5098/hmt.v2.3.3008

Abstract Detailed flow structure in turbulent flows through a rectangular channel containing built-in winglet type vortex generators have been analyzed by means of solutions of the full Navier-Stokes equations using a Large-Eddy Simulation (LES) technique. The Reynolds number of investigation is 6000. The geometry of interest consists of a rectangular channel with a built-in winglet pair on the bottom wall with common-flow-down arrangement. The winglet pair induces streamwise longitudinal vortices behind it. The vortices swirl the flow around the axis parallel to the mainstream direction and disrupt the growth of thermal boundary layer entailing enhancement of… More >

Chein-Shan Liu ^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.17, No.2, pp. 73-94, 2007, DOI:10.3970/cmes.2007.017.073

Abstract The primary objectives of the present exposition focus on five different types of representations of the plastic equations obtained from an elastic-perfectly plastic model by employing different corotational stress rates. They are (a) an affine nonlinear system with a finite-dimensional Lie algebra, (b) a canonical linear system in the Minkowski space, (c) a non-canonical linear system in the Minkowski space, (d) the Lie-Poisson bracket formulation, and (e) a two-generator and two-bracket formulation. For the affine nonlinear system we prove that the Lie algebra of the vector fields is so(5,1), which has dimensions fifteen, and by the… More >

M. M. Rahman¹, A.K. Ariffin, N. Jamaludin, C. H. C. Haron

Structural Durability & Health Monitoring, Vol.2, No.2, pp. 69-82, 2006, DOI:10.3970/sdhm.2006.002.069

Abstract This paper describes finite element based vibration fatigue analysis techniques to predict fatigue life using the narrow band frequency response approach. The life prediction results are useful for improving the component design at a very early development stage. The approach is found to be suitable for periodic loading but requires very large time records to accurately describe random loading processes. The focus of this paper is to investigate the effects of surface treatments on the fatigue life of the components of free piston linear engine. The finite element modeling and frequency response analysis have been… More >

Jae Bong Lee¹, Jai Hak Park¹, Sung Ho Lee², Hong-Deok Kim², Han-Sub Chung²

CMES-Computer Modeling in Engineering & Sciences, Vol.11, No.1, pp. 9-16, 2006, DOI:10.3970/cmes.2006.011.009

Abstract The growth of stress corrosion cracks in steam generator tubes is predicted using the Monte Carlo simulation and statistical approaches. The statistical parameters that represent the characteristics of crack growth and crack initiation are derived from in-service inspection (ISI) non-destructive evaluation (NDE) data. Based on the statistical approaches, crack growth models are proposed and applied to predict crack distribution at the end of cycle (EOC). Because in-service inspection (ISI) crack data is different from physical crack data, a simple method for predicting the physical number of cracks from periodic in-service inspection data is proposed in More >