Papers by Keyword: Heat Source

Abstract: High-velocity oxy-fuel spraying is a widely used thermal spray technology for producing dense and wear-resistant coatings. The thermal input during spraying strongly influences coating microstructure, residual stress state, and substrate integrity. In this work, in situ thermal measurements were performed on S235 substrates during High-velocity oxy-fuel deposition of 316L coatings. Two spraying strategies were compared: (i) single-pass rotation and (ii) multi-pass rotation. Thermocouples embedded at 1.8mm depth captured transient temperature responses, revealing significant thermal cycling effects. Single-pass operations produced no significant heating–cooling cycles, while multi-pass strategies led to thermal accumulation and overlapping cycles. The results provide reference data for the calibration of finite element heat source models and support the development of process–structure–property relationships in High-velocity oxy-fuel coatings.

Abstract: An inverse problem involves determining unknown physical quantities denoted as u = (u₁, ..., u_np), which cannot be directly measured but need to be evaluated based on accessible measurements, represented as y = M(u), where M is a mathematical model. Solving such problems often requires mathematical techniques like differential equations or optimization methods such as least squares. Inverse problems can be well-posed (stable, unique solutions) or ill-posed (unstable or non-unique), with ill-posedness often resulting from poor experimental setups or measurement errors. This study addresses the identification of thermophysical parameters - specifically thermal conductivity and heat transfer coefficients—in a 2D steady-state diffusive medium. The proposed method uses a boundary element approach and an iterative descent algorithm to minimize a functional and identify the unknown parameters, validated through simulated thermograms. As a result, the use of sensitivity functions to weight the functional to be minimized makes it possible to avoid selection of the sensors according to the parameter to be identified.

Abstract: A numerical simulation of turbulent mixed convection of a ventilated cavity containing a heat source placed of the center has been carried out. This cavity is outfitted along couple holes: one placed within the lower left corner and the other in the top right corner. The width of the hole "H" represents is 1/5 of the length of the cavity side. The diameter regarding the round heat source "D" is equal in accordance with the breadth of the inlet gap’s H (D = H). The walls of the cavity considered are maintained adiabatic, while the temperature of the heat source T is higher than the ambient temperature. The turbulence model k-ε was used for governing equations of turbulent mixed convection inside the cavity. The finite volume method was used for numerical resolution. The parameters of flow are: the Grashof number is set to Gr = 10⁹ and the Reynolds number (Re) varies so that the number of Richardson (Ri) takes the values Ri = 0.01, 0.05, 0.1, 1, 2, 5, 10, 20 and 30 (Ri = Gr/ Re²). The effect of thermo-dynamic parameters and the shape geometric cavity effect are investigated.

Abstract: Forced convection in a ventilated enclosure with aspect ratio 2 is studied. Three heat sources simulating electronic component are placed in the bottom wall of the cavity, all walls are kept insulated. With varying the inlet and the outlet location of cold air firstly then swapping the location of the heat sources, the optimal cooling strategy was identified. Consideration was given to steady two-dimensional laminar flow and Reynolds number (Re) in the range 10–1500. The governing equations along with the boundary conditions are solved by using the control volume method. Calculations showed that enhancement in heat transfer occurred, and the results indicate that there exists an optimal location of ventilation ports and an optimal disposition of heat sources for which the heat transfer is maximized for all ranges of Reynolds numbers.

Abstract: A finite element model was developed to determine the temperature distribution in the preheating phase of the friction surfacing (FS) process. In the present study consumable rod was used as a tool. As a model of the heat source, a model applicable to the traditional friction stir welding (FSW) was used. The developed model has been validated by a full-scale experiment. Temperature fields were obtained for different modes of the FS process, where the variable parameters were the axial force and the speed of rotation of the consumable rod. The difference between calculated and experimental data is less than 10%. Influence of the axial force magnitude on the consumable rod and the rod rotation speed on the temperature field generated by friction and plastic deformation of the consumable rod was established.

Abstract: Additive technologies, in particular, wire-feed laser deposition, can significantly reduce the production cycle of manufacturing large-sized parts or parts of complex shape due to partial or complete elimination of technological operations such as casting, machining and welding. The aim of the work is to develop an analytical model of heating and melting of the filler wire during wire-feed laser deposition. The heat conduction problem was solved by the functional-analytical methods. The practical effectiveness of the functional-analytical methods with respect to computational time is several orders of magnitude higher than numerical ones. Obtained analytical solution made it possible to determine the temperature field for heat flux arbitrarily distributed on the filler wire surface. It is established that at a higher feed rate, the wire tip is completely melted at a greater distance from the laser axis. The shape of the melting surface also depends on the feed rate. At a slow feed rate, a more uniform heating of the wire over the cross section occurs. The melting surface has a small angle of inclination.

Abstract: In this study, the numerical computation is used to investigate the transient movement of a water droplet in a microchannel. For tracking the evolution of the free interface between two immiscible fluids, we employed the finite element method with the two-phase level set technique to solve the Navier-Stokes equations coupled with the energy equation. Both the upper wall and the bottom wall of the microchannel are set to be an ambient temperature. 40mW heat source is placed at the distance of 1 mm from the initial position of a water droplet. When the heat source is turned on, a pair of asymmetric thermocapillary convection vortices is formed inside the droplet and the thermocapillary on the receding side is smaller than that on the advancing side. The temperature gradient inside the droplet increases quickly at the initial times and then decreases versus time. Therefore, the actuation velocity of the water droplet first increases significantly, and then decreases continuously. The dynamic contact angle is strongly affected by the oil flow motion and the net thermocapillary momentum inside the droplet. The advancing contact angle is always larger than the receding contact angle during actuation process.

Abstract: This research work is focused on the effects of combined heat and mass transfer on MHD stagnation point flow of Carreau nanaofluid embedded in porous medium with heat source. Thermal radiation and chemical reaction are also taken into account. The governing non-linear PDEs are transformed into a set of non-linear coupled ODEs which are then solved numerically by using the Runge– Kutta–Fehlberg fourth–fifth order method along shooting technique. The graphical and tabular results elucidate the influence of different non-dimensional governing parameters on the velocity, temperature and concentration fields along with the wall friction, local Nusselt and Sherwood numbers. We found the dual nature of the solutions for suction and injection cases. A good agreement of the present results has been observed by comparing with the existing literature results.

Abstract: In this paper, we conducted the thermodynamics first and second laws analyses on hydromagnetic boundary layer flow of an incompressible electrically conducting viscous fluid past a vertically stretching sheet embedded in a porous medium with heat source and thermal radiation. The governing equations describing the problem are converted to a system of nonlinear ordinary differential equations using appropriate similarity variables. Using shooting technique coupled with Runge-Kutta-Ferhlberg integration scheme, the model boundary value problem is numerically tackled. The parametric effects on fluid velocity, temperature, skin friction, Nusselt number, entropy generation rate and the Bejan number are presented graphically and discussed quantitatively. Our results revealed among others, that the entropy generation is enhanced by magnetic field, thermal radiation and heat source but lessened by increasing porous medium permeability and buoyancy force.

Abstract: A mathematical model is established to examine the influence of viscous dissipation and joule heating on magnetohydrodynamic (MHD) flow of an incompressible viscoelastic nanofluid over a convectively heated stretching sheet. Brownian motion and thermophoresis effects have been introduced in this nanofluid model. The governing equations are transformed into ODE’s by using suitable similarity conversions and are then solved numerically by the most robust shooting technique. The significance of numerous physical flow constraints is performed for, and distributions through graphs. It is noticed that, the increases for higher values of and reduces for rising values of heat source and Biot numbers. An outstanding contract was found between our numerical results and previously publicised results.