In-cylinder in-depth combustion investigation for a heavy-duty diesel engine

t This present study is part of the design improvement process of a specified high torque low-speed engine.This work aims at carrying out an in-depth analysis of in-cylinder combustion,mesh sensitivity,and engine performance at supercharge conditions to provide a foundation for the design improvement process of the given engine.The computational fluid dynamic(CFD)simulations are carried out on a 3D sector from-130°to 130°crank angle(CA)by employing appropriate models to represent the different physical and chemical processes and using the finite volume method for solving the governing differential equations.An extensive investigation has been carried out for the choice of base mesh size and the number of local and temporal refinements to capture the phenomena happening in the combustion chamber at diverse temporal and local scales.The present results have been validated against available literature experimental and simulation results.Primary field variables and the wellknown four phases of combustion have been studied for gaining in-depth insight into these phenomena.Cylinder average pressure,mean temperature,heat release rate(HRR),integrated heat release rate(IHRR),and emissions of CO2,CO,NOx,HC and soot are presented to assess the quality of combustion.Engine performance analysis has been done in terms of combustion ef-ficiency,gross work,power,torque,and integrated mean effective pressure(IMEP).The base mesh of 1.4 mm may be an appropriate choice during the injection and combustion process spanning throughout around 40CA from the start of injection while in the remaining simulation duration of around 220CA base mesh of 2 mm gives a sufficient resolution.It has been found that maximum heat release takes place in Phase-III,the mixing-controlled phase,of the combustion process.More than 98%combustion efficiency has been achieved in all the simulations.Around 99%of the total heat release and emissions production takes place within 60CA after top dead center(ATDC).

Numerical Investigation of the Pulsatile Flow of Viscous Fluid in Constricted Wall Channel with Thermal Radiation

The main theme of the current article is to investigate the heat transfer in the pulsatile flow of an electrically conducting viscous fluid in a constricted channel under the effect of the magnetic field and thermal radiation.The unsteady governing equations simplified for low conducting fluids are solved numerically by finite difference method using stream-vorticity function formulation.The influence of the flow parameters such as the Hartmann number(magnetic parameter),Strouhal number(flow pulsation parameter),Prandtl number,and radiation parameter is studied on the relevant flow profiles.The influence of different emerging parameters on the skin friction coefficient and Nusselt number are examined,as well.In general,the profiles are observed to exhibit a relatively more regular pattern upstream of the construction than that downstream of the constriction.