Spray Breakup Modelling for Internal Combustion Engines

Abstract

Rising concerns about emissions have led to a significant tightening of pollution norms for internal combustion (IC) engines. High-pressure direct injection (HPDI) technologies have been adopted for most on-road and off-road engines to meet the global demand for clean and efficient powertrains. Higher fuel efficiency, superior combustion, and lower pollutant formation are the characteristic features of the HPDI. The introduction of alternative fuels, modified combustion geometry, and novel combustion concepts demand continuous improvement in fuel injection equipment (FIE). The complicated physics of HPDI and its modelling is an active area of research among researchers and engine developers. Fuel-injected in the combustion chamber breaks up into a spray of fine droplets, evaporating, mixing with ambient air, and forming a fuel-air mixture, greatly affecting the engine combustion and emission characteristics. Therefore, it is necessary to study the fuel breakup phenomenon under different engine conditions comprehensively. Detailed understanding of the spray breakup phenomenon is unavailable due to difficulties in optical access, highly dense sprays, complex processes, etc. However, recent advances in measurement technologies and computational tools have made it feasible for researchers. This chapter attempts to capture widely used spray breakup models and research studies involving IC engines. Fundamental spray breakup and atomization have been discussed at the beginning of the chapter. Subsequently, the basis and fundamentals of popular spray models have been discussed. Finally, the authors have comprehensively discussed the key contributions in sprays to provide an overall idea about the spray models and their application for IC engine studies. Various spray breakup models such as Blob Model, Linear Instability Sheet Atomization (LISA) Model, Kelvin-Helmholtz (KH) Model, Kelvin-Helmholtz-Aerodynamics Cavitation Turbulence (KH-ACT) Model, RT (Rayleigh-Taylor) Model, Hybrid/Modified Kelvin-Helmholtz Rayleigh-Taylor (KH-RT) Model, Taylor Analogy Breakup (TAB) Model, Enhanced TAB breakup model (ETAB) are discussed briefly in this chapter. Towards the end, a summary of the contents of the chapter is provided, which covers highlights and significant observations.