Hongliang Luo

By Hongliang Luo

Spray-wall impingement is a widespread phenomenon applied in many fields, including spray-wall cooling system, spray coating process and fuel spray and atomization in internal combustion engines. In direct-injection spark ignition (DISI), it is difficult to avoid the fuel film on the piston head and cylinder surfaces. The wet wall caused by impingement affects the air-fuel mixture formation process, which finally influence the subsequent combustion efficiency and performance. Therefore, the fuel spray and impingement under gasoline engine-like conditions were characterized. Mie scattering technique was applied to visualize the spray evolution and impingement processes in a high-pressure and high-temperature constant chamber. Meanwhile, the adhered fuel film on the wall was measured by refractive index matching (RIM) under non-evaporation and evaporation conditions considering the effects of different injection pressures, ambient pressures and ambient temperatures. Additionally, the fuel film formation and evaporation evolution models were proposed with the help of these mechanisms.

Part of the book: Internal Combustion Engine Technology and Applications of Biodiesel Fuel

By Hongliang Luo and Feixiang Chang

Microscopic characteristics of fuel spray are very important for atomization and mixture formation. The droplet size, number density, velocity distribution as well as minimum distance reveal the quality of spray and atomization, which affects the subsequent combustion and emissions for different engines such as vehicle, marine and aircraft. Moreover, in the internal combustion engine, the spray-wall impingement is difficult to avoid, which is the main source for soot emissions. Nowadays, regulations for emissions become straight by governments. Therefore, it is urgent for us to alleviate the energy and emissions crisis. In this study, the droplets behaviors will be characterized under the related engine working state. Firstly, the experimental setup and measurement were explained in detail. Then, images process method was induced to calculate the droplet size, velocity and distance among them. Finally, results of the impinging spray were presented. One thing should be noted, as the dense region is not available to detect the droplets by the observation. Therefore, a spray “slicer” was designed and applied to cut the spray slim. Finally, multi-droplets were generated, and the results can be concluded as well. All the results could provide insights into the impacting behaviors for better understanding the droplet dynamics.

Part of the book: Fundamental Research and Application of Droplet Dynamics

By Hongliang Luo

Part of the book: Fundamental Research and Application of Droplet Dynamics