Modeling and Analysis

Computer simulations of the working process of internal combustion engine are usually performed using multi-dimensional computational fluid dynamics (CFD) and/or advanced one-dimensional gas dynamics and thermodynamic models. Since the fuel and oxidizing agents do not mix earlier to the entrance into the combustion chamber, therefore Non-Premixed model is considered and the species are transported in the form of a PDF file. Due to a fully symmetric design, only half of the cylinder was being simulated by using the symmetry boundary condition to decrease the computational effort and hence the time. Viewing directly on to the symmetry plane of the cylinder, the topology of the mesh shown with piston being positioned at different crank angles. During the compression and expansion strokes, several cell layers in the cylinder perpendicular to the main axis and, additionally, in the valve curtain area are added or removed using a mesh interpolation technique, also called rezoning.

Figure showing the velocity contour for 340 degree crank
2 angle at an injection pressure of 200 kg/cm

Conclusion

As a first step, the computed histories of certain global parameters like average cylinder pressure and pollutant emissions are compared with the available experimental results. A single cylinder diesel engine with hemi-spherical bowl shape in the piston is considered for the analysis. The variations in the global parameters with crank angle, during compression and expansion processes, are presented in x-y plots. Further, the global parameters are predicted with standard K- epsilon model. In the second stage, detailed analysis of spatial information, predicted using CFD code modified with standard Kepsilon model, such as, turbulent kinetic energy, turbulent intensity, fuel variance, residuals and temperature variations with crank angle is presented for Hemispherical bowl in- piston configuration. The local flow field is presented in the form of velocity vectors. Hence the analysis proved that the properties of cotton seed-diesel blends are comparable with those of pure diesel and also there is significant effect of injection pressure on engine performance.