In order to improve the performance of a mini-type air-cooled diesel engine in terms of the overall efficiency and engine emissions, a swirl chamber of a variable cross-section dual-channel model was developed. This study proposed nine turbulent swirl chambers with a variable cross-section for a dual-channel combustion solution, which applied a dual-channel cross-section to the insert between the original swirl chamber and the main chamber. Model-based design, simulation and experiments were applied as a feasible approach to address this issue to find out the influence of the dual-channel inclination angle and divergence angle on the swirl rate in the swirl chamber, the power and the emissions performance, including the fuel efficiency. By comparing the tests, the performance of the diesel engine with a variable cross-section dual-channel swirl chamber was superior to the original one with a single channel in terms of the swirl rate, fuel consumption rate and emissions.

Blending gasoline with hydrogenated catalytic biodiesel has the potential to improve combustion problems of gasoline direct-injection compression combustion, and the spray characteristics of the blending fuel can directly affect the combustion effect. In order to understand the spray characteristics of a gasoline–hydrocatalyzed catalytic biodiesel mixture, a numerical spray model of constant volume combustion chamber was established, and the accuracy of the model was verified by experimental data in the literature. Based on this model, the spray penetration, sauter mean diameter, spray velocity field and concentration field of gasoline–hydrocatalyzed catalytic biodiesel at different blending ratios were studied. The results show that under the conditions of 850 K ambient temperature, 5 MPa ambient pressure, and 80 MPa injection pressure, as the proportion of hydrogenated catalytic biodiesel in the blending fuel increases, the spray penetration increases, the sauter mean diameter decreases slightly, and the area of high velocity and high concentration at the spray center increases. The results of this study will contribute to the development of blended fuels for superior combustion performance and reduced pollutant emissions at appropriate blending ratios.