Influence of Various Fuel Nozzle Hole Designs on Cavitation: A Diesel and Biodiesel Comparison

Cavitation plays a critical role in reducing the effective flow area of fuel nozzles, leading to increased pressure losses and potential mechanical degradation. This study enhances previous research by incorporating a comparative analysis of diesel and biodiesel to examine how cavitation behavior varies under different nozzle geometries. A three-dimensional computational analysis is performed using OpenFOAM® to investigate the relationship between nozzle shape, cavitation intensity, and fuel atomization. While prior investigations have primarily emphasized conical spray holes with tapered outlets and rounded inlets to counteract cavitation, this work explores alternative geometries, including constricted, expanded, and progressively widening nozzle hole designs. The simulations demonstrate that cavitation intensity and fuel atomization are highly dependent on both nozzle geometry and fuel properties. Due to its higher viscosity, the cavitation patterns of biodiesel, compared to those of diesel, are expected to influence turbulence levels and vapor formation within the nozzle. Results indicate that designing nozzle holes with a wider inlet and a narrower outlet can effectively minimize cavitation while enhancing atomization. Specifically, a nozzle profile that narrows toward its midsection leads to a substantial reduction in the vapor volume ratio. Additionally, since cavitation contributes to turbulence, modifying the nozzle geometry provides a means to control its distribution, optimizing fuel injection efficiency for both diesel and biodiesel applications. This study offers valuable insights into fuel nozzle design improvements to reduce cavitation-induced wear and enhance combustion performance.