Search

Until now, there has been a lack of two-phase velocity and vapor investigations under the evaporation condition. Therefore, this work addresses this title in order to be additive to this subject. The spray droplets are modelled using the moments method, and the gas phase is modelled using the Eulerian approach. The spray drag, breakup, and evaporation sub-models are taken into account. Based on the RANS turbulence model for the carrier gas phase and a calibrated atomisation model for the dispersed droplets, turbulence closure is accomplished. The spray tip penetration is evaluated and compared with experimental data. The fuel vapour mass fraction is calculated by using a transport equation for the droplet-gas interaction. The distribution of the fuel vapour mass fraction is compared with the KIVA code. Fortunately, there are no experimental results for the spray or gas velocity to be compared with. All presented results are investigated by their variation with positions and time to give the total behaviour. The fuel vapour mass fraction distribution exhibits a bell-shaped behaviour. In close proximity to the injector, the evaporation rate is significantly higher. There was no significant increase in the evaporation rate of the pressure swirl nozzle as the distance from the injector increased. During the evaporation of spray droplets, higher fuel vapour concentrations are present at the core spray than at the peripheral edge. The droplet velocities in the outer edge’s axial and radial directions display a reduced magnitude. The droplet’s diameter is greater at the inner edge than at the outer edge. The comparisons showed that there was good agreement with both the experimental and numerical results.

This study presents a novel investigation into the thermal behavior of a hybrid nanofluid (MgO − Ag − H2O) in natural convection around a porous fin in a triangular enclosure under the influence of radiation and magnetohydrodynamic effects. The research uniquely combines these complex phenomena, addressing a significant gap in the literature. This configuration has potential applications in advanced solar thermal collectors, electronic cooling systems for high-power devices, and compact heat exchangers in various industries. The main objectives are to understand how various parameters influence heat transfer and fluid flow behavior and to optimize the design for enhanced thermal performance. The study considers a range of variables including Rayleigh number (103 − − 106), Hartmann number (0 – 50), Aspect ratio (0.3 – 0.6), radiation parameters (Rd = 1 − − 5, λ = 1 − 5), and volume concentration (0- 0.05), which have been numerically analyzed using the finite element method (FEM). The findings reveal that increasing the Darcy number (Da) enhances heat transfer at low Rayleigh numbers (Ra = 103,104). However, at higher Ra (Ra = 106), the impact of Da becomes more complex, with a critical Da beyond which heat transfer efficiency decreases due to an increase in flow resistance. The nanoparticle volume concentration plays a vital role, as higher concentrations lead to improved heat transfer efficiency, especially at higher Ra, through enhanced thermal conductivity and thermal dispersion. The length of the porous fin greatly impacts fluid flow patterns and heat transfer rates, with longer fins creating more complex flow patterns, promoting enhanced heat transfer and stronger thermal plumes. Thermal radiation, represented by the radiation parameters (Rd and λ), significantly influences both the heat transfer rate and the convective flow patterns within the enclosure. This study also incorporates a comprehensive entropy generation analysis, providing novel insights into system irreversibilities and optimization potential. The entropy analysis reveals the complex interplay between various parameters and their impact on system efficiency, offering valuable guidance for designing high-performance thermal management systems.

Mixed convection convection is a vital subject and it is beneficial in many engineering applications. The current paper addresses this subject with a novel geometry and very vital variables including magnetohydrodynamic influences on the forced/free convection as well as the reproduction of irreversibilities in an enclosure filled with water/carbon nanotubes (CNT) and a nonadiabatic cylinder. The top wall is split from the middle and moves in different directions to drive the isotherms which are generated from the bottom wall and cold from the vertical surfaces. The numerical analysis was carried out using finite element method; the variables are Reynolds number (40–200), Richardson number (0.01–10), Hartmann number (0–62), inclined magnetohydrodynamic angle (0–60), volume concentration (0–0.08) while Prandtl number has kept constant at 6.2. The results show that the transformation of heat, as well as the fluid flow, are largely influenced by the change of variables, where increasing Reynolds number, Richardson number enhances heat and increases the flow circulation. Furthermore, heat transfer enhances by 57 % when increasing Ri from 0.1 to 10 at Re=41 and this enhancement increases to 62.5 % at Re = 200. Furthermore, increasing the concentration of the carbon nanotube can cause heat transfer but decrease the circulation of the fluid. In contrast, the transfer of heat as well as the flow streams are remarkably decreased with the increase of the Hartmann at zero inclination angle; however, the value of the Nusselt average increases with the increase of the inclination angle. Moreover, the value of Nusselt average decreses by 34.7 % when increasing Ha from 0 to 62 at Re = 200. Furthermore, the total entropy generation increases as Richardson number, Reynolds number, and volume concentration increase; in contrast, detraction with the rise of the MHD.

Unsteady study of the natural convection of aluminum oxide-water nanofluid within a trapezoidal geometry containing a circular cylinder located at its center. Finite Element method has been considered for the numerical analysis. The proposed investigation handled the impact of Rayleigh number (103–105), chemical reaction parameter (0–4), aluminum oxide nanoparticles volume fraction (0–0.06), magnetic field (0–63) and its inclination angle (0°–90°), and circular obstacle diameter (0.3–0.7) effects on time-dependent natural convection of Al2O3–H2O nanofluid. On the other hand, the value of Prandtl number has kept constant at (Pr = 6.2). Since the nanofluid mobility at φ = 0.02, Ha = 3, and Fk = 1 significantly improved, the heat transfer rate achieved its maximum intensity at Ra = 105. Research also reveals a little effect on heat transfer by increasing the fraction of nanoparticles. Additionally, as Ha intensifies from 0 to 63, a final change in the mean Nusselt number of 28.65 % is displayed. Finally, as the magnetic field angle of rotation is diminished, more enhancement in heat transmission is achieved. This research provides insights into the intricate relationship between natural convection and exothermic reaction under the influences of various conditions. This can illustrate the flow and thermal behaviors of nanofluid in such non-uniform shapes in many engineering applications.

In this study, numerical analysis of a porous block influence on the mixed convection in a cavity filled with nanfluid has been investigated. The cavity is curvilinear shaped, in which the cold side is the top which is split to move in two directions on the same plane. The base is partially heated and connected to a block of porous media, while other walls are adiabatic. The complex governingequations are solved numerically using the finite element technique. For the assessment of the thermal performance, the considered variables which are Richardson number (from 0.15 to 10), Reynolds number (from 25 to 200), Darcy number (from 10−5 to 10−1), Hartmann number (from 0 to 62), ma magnetohydrodynamic's inclination angle (from 0° to 90º) and nanoparticles concentration (from 0 to 0.08). The height of the porous block is also investigated. The results’ main finding stated that the heat transfer could be enhanced due to the rise in Reynolds number, Richardson number, and the volume concentration while decreasing with the rise of Hartmann number. Also, value of Nuavg and the streams’ strength increase with the increase in Darcy number.