Approaches for Detailed Investigations on Transient Flow and Spray Characteristics during High Pressure Fuel Injection

Abstract

High pressure injection systems have essential roles in realizing highly controllable fuel injections in internal combustion engines. The primary atomization processes in the near field of the spray, and even inside the injector, determine the subsequent spray development with a considerable impact on the combustion and pollutant formation. Therefore, the processes should be understood as much as possible; for instance, to develop mathematical and numerical models. However, the experimental difficulties are extremely high, especially near the injector nozzle or inside the nozzle, due to the very small geometrical scales, the highly concentrated optical dense spray processes and the high speed and drastic transient nature of the spray. In this study, several unique and partly recently developed techniques are applied for detailed measurements on the flow inside the nozzle and the spray development very near the nozzle. As far as possible, the same three-hole injector for high pressure diesel injection is used to utilize and compare different measurement approaches. In a comprehensive section, the approach is taken to discuss the measurement results in comparison. It is possible to combine the observations within and outside the injector and to discuss the entire spray development processes for high pressure diesel sprays. This allows one to confirm theories and to provide detailed and, in parts, even quantitative data for the validation of numerical models.

Spray Breakup Modelling for Internal Combustion Engines

“…The new parcel provided similar properties as the parent parcel, excluding radius and velocity. The secondary breakup of child droplets happens because of the competing effects of KH and RT models (Kawaharada et al 2020). Cavitation and turbulence inside the nozzle greatly influence primary breakup; hence primary breakup should incorporate these effects.…”

“…However, most diesel engine simulations employ KH-RT atomization models. Many simulation studies employed KH and KH-RT models for primary and secondary breakup (Kawaharada et al 2020;Reitz and Bracco 1982). This modelling methodology is computationally cost-effective and replicates global spray characterization closely.…”

Visualization of Water Toroidal Vortex by Multicolor Particle Image Velocimetry

“…To optimize the flow mixing process in such devices, it is important to know the flow structure and the mixing mechanism. Various devices with flow twist are used in a number of sectors of the national economy: vortex chamber reactors in chemical technology, centrifugal casting in metallurgy, vortex and turbine flowmeters in measuring technology [4][5][6][7][8][9][10].…”