New induction manifold designs have been developed in this work to enhance the turbulence intensity and improve the mixing quality inside diesel engine cylinders. These new designs employ a spiral-helical shape with three different helical diameters (1D, 2D, 3D; where D is the inner diameter of the manifold) and three port outlet angles: 0 deg, 30 deg, and 60 deg. The new manifolds have been manufactured using three-dimensional printing technique. Computational fluid dynamics simulations have been conducted to estimate the turbulent kinetic energy (TKE) and the induction swirl generated by these new designs. The combustion characteristics that include the maximum pressure raise rate (dP/dθ) and the peak pressure inside the cylinder have been measured for a direct injection (DI) diesel engine utilizing these new manifold designs. In addition, engine performance and emissions have also been evaluated and compared with those of the normal manifold of the engine. It was found that the new manifolds with 1D helical diameter produce a high TKE and a reasonably strong induction swirl, while the ones with 2D and 3D generate lower TKEs and higher induction swirls than those of 1D. Therefore, dP/dθ and peak pressure were the highest with manifolds 1D, in particular manifold m (D, 30). Moreover, this manifold has provided the lowest fuel consumption with the engine load by about 28% reduction in comparison with the normal manifold. For engine emissions, m (D, 30) manifold has generated the lowest CO, SO2, and smoke emissions compared with the normal and other new manifolds as well, while the NO emission was the highest with this manifold.

Investigating the Effect of Utilizing New Induction Manifold Designs on the Combustion Characteristics and Emissions of a Direct Injection Diesel Engine

Numerical simulation on fluid flow and temperature prediction of motorcycles based on CFD

This study aims to enhance the turbulence of direct injection (DI) diesel engine by modifying the inlet manifold design with an inclined nozzle-like provision angles of 30°, 60°, and 90° along with its regular intake system. Numerical analysis was carried out using the computational fluid dynamics package (STAR-CD libraries of es-ice) to study the flow field and combustion characteristic with the modified intake manifold geometries. The computational investigation was carried out for both single and double pass conditions at 1500 rpm under high-load operating condition (5.2 kW). The computational results showed that the velocity magnitude of modified single pass intake manifold increases by about 10% that results in higher turbulence even near the point of fuel injection. Through the modification in the inlet manifold, the combustion parameters such as in-cylinder pressure and in-cylinder temperature are increased as compared to the standard manifold for the same quantity of fuel injected per cycle. In summary, the 60° modified manifold with a single pass shows better combustion and emission characteristics compared to that of regular inflow manifolds due to the improvement in turbulence levels.

Giacomo Cuneo

Papers

Numerical Simulation of Intake Port and In-Cylinder Flow in a Two-Valve Multi-Cylinder Diesel Engine