Open Access

ARTICLE

Investigations on High-Speed Flash Boiling Atomization of Fuel Based on Numerical Simulations

by Wei Zhong¹, Zhenfang Xin², Lihua Wang^1,*, Haiping Liu²

1 School of Aerospace Engineering and Applied Mechanics, Tongji University, Shanghai, 200092, China
2 Beijing Mechanical Equipment Research Institute, Beijing, 100854, China

* Corresponding Author: Lihua Wang. Email:

(This article belongs to the Special Issue: Advanced Computational Methods in Fluid Mechanics and Heat Transfer)

Computer Modeling in Engineering & Sciences 2024, 139(2), 1427-1453. https://doi.org/10.32604/cmes.2023.031271

Received 31 May 2023; Accepted 17 November 2023; Issue published 29 January 2024

Abstract

Flash boiling atomization (FBA) is a promising approach for enhancing spray atomization, which can generate a fine and more evenly distributed spray by increasing the fuel injection temperature or reducing the ambient pressure. However, when the outlet speed of the nozzle exceeds 400 m/s, investigating high-speed flash boiling atomization (HFBA) becomes quite challenging. This difficulty arises from the involvement of many complex physical processes and the requirement for a very fine mesh in numerical simulations. In this study, an HFBA model for gasoline direct injection (GDI) is established. This model incorporates primary and secondary atomization, as well as vaporization and boiling models, to describe the development process of the flash boiling spray. Compared to low-speed FBA, these physical processes significantly impact HFBA. In this model, the Eulerian description is utilized for modeling the gas, and the Lagrangian description is applied to model the droplets, which effectively captures the movement of the droplets and avoids excessive mesh in the Eulerian coordinates. Under various conditions, numerical solutions of the Sauter mean diameter (SMD) for GDI show good agreement with experimental data, validating the proposed model’s performance. Simulations based on this HFBA model investigate the influences of fuel injection temperature and ambient pressure on the atomization process. Numerical analyses of the velocity field, temperature field, vapor mass fraction distribution, particle size distribution, and spray penetration length under different superheat degrees reveal that high injection temperature or low ambient pressure significantly affects the formation of small and dispersed droplet distribution. This effect is conducive to the refinement of spray particles and enhances atomization.

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Keywords

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