• Corpus ID: 212527151

A comprehensive Parametric Study of the Effect of Cavitation Formation Inside Fuel Injector Nozzle with Different Needle Seat Shapes

@inproceedings{Amirahmadian2017ACP,
  title={A comprehensive Parametric Study of the Effect of Cavitation Formation Inside Fuel Injector Nozzle with Different Needle Seat Shapes},
  author={Sepideh Amirahmadian},
  year={2017}
}

• Sepideh Amirahmadian
• Published 2017
• Engineering

In this work, fluid flow inside three liquid fuel injector nozzles was simulated numerically using Ansys-Fluent v16 commercial code. A mixture model along with the k-ε turbulence model was used to handle the two-phase and turbulent nature of this flow. The Schnerr-Sauer model was used to model the cavitation phenomena. After validation of the present numerical scheme using Winklhofer rectangular shape nozzle, a real size four-hole injector nozzle was used to investigate in detail the effects of pressure difference, cavitation number and needle height on the flow pattern. It was found that with increase of the cavitation number the cavitation length increases. The results indicate that for the case with larger needle height, the vapor volume fraction inside the injector nozzles is significantly larger. It was also concluded that increasing the cavitation number and needle height can increase discharge coefficient until occurrence of a fully cavitating field inside the injector. In the second part of the present study; VCO (Valve-Covered-Orifice), improved and standard injector nozzle with different seat shapes were simulated in order to investigate the effect of the valve seat shape on the cavitation phenomena. Numerical simulation also shows that in all three injector nozzles that have been computationally analyzed in this work, increasing the cavitation number can increase the discharge coefficient, but for the injector with standard seat shape, the discharge coefficient has smaller value in comparison with the other two injector nozzles. In addition, flow separation area due to the low pressure field is much larger in the standard nozzle compared to VCO nozzle and the improved nozzle. Under similar boundary conditions, the standard nozzle has larger vapor volume fraction length than in case of two other nozzles, while the vapor volume fraction region for the improved nozzle is much shorter. Lastly, formation of turbulent intensity along the orifice of the three aforementioned nozzles is highly different. The turbulent intensity for standard nozzle is larger compared with the two other nozzles. Therefore, it can be pointed out that although standard nozzle has lower discharge coefficient compared to the two other nozzles analyzed, the higher value of turbulent intensity and vapor volume fraction for this type of nozzle shows that air-fuel mixtures have better quality in this injector nozzle than in two other nozzles considered in this analysis.