Loading...

Investigation of the Droplet Size and Velocity Distribution During the Atomization of a Liquid Jet Subjected to a Cross-Flow for Circular and Rectangular Nozzles

Saeedian Sar, Erfan | 2024

0 Viewed
  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 57550 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Kebriaee, Azadeh
  7. Abstract:
  8. In this research, the distribution of droplet size and velocity in a liquid jet and sheet injection into cross-flow was investigated. For this porpuse, four different nozzles were tested, two with circular geometries and two with rectangular geometries, and their hydraulic diameters were also pairwise different, in order to investigate the effects of nozzle geometry and hydraulic diameter on the distribution of droplet size and velocity. To investigate the effects of liquid and gas flow on the macroscopic properties of droplets, the cross-flow velocity of air was varied from 20 to 35 m/s, and the injection flow rate of the liquid from the nozzle was varied from 3 to 10 m/s. Moreover, measurements were taken at different distances and spatial positions relative to the spray nozzle, in three dimensions, in order to obtain the spatial distribution of the desired measured parameters. For the advancement of this research, an experimental method was used to measure droplet size and velocity. The prepared test bed had the capability of high-precision imaging of droplets, and the shadowgraphy method was used to image the droplets. The images obtained from the experiments were converted into numerical data on the average diameter and average velocity of droplets using image processing methods. Finally, data science methods such as analysis of covariance, multiple linear regression, and standard statistical tests were used to analyze the data. Investigation of the effects of flow on droplet size showed that in the present flow regime, the momentum ratio of the injected fluid to the cross-flow plays a fundamental role in determining the droplet size, and with its increase, the droplet size decreases. Also, in the investigations, a critical Weber number was identified for the cross-flow, which the effects of the cross-flow on the diameter were increasing before that, and after that, they were decreasing. The study of the data showed that increasing the velocity of the injected fluid or the cross-flow would increase the velocity of the produced droplets. Also, the droplet size and their velocity generally have an inverse relationship with each other. The investigation of the effects of nozzle diameter and shape showed that rectangular nozzles can generally produce smaller droplets. Also, increasing the hydraulic diameter of the nozzle will increase the diameter of the produced droplets. Finally, power-law relationships were presented for the distribution of droplet size and velocity, based on the flow conditions and spatial position for each of the nozzles. In the end, the possibility of using neural networks to fit the existing data for nozzles was investigated, and it was observed that neural networks can predict the droplet size well with the existing data and provide higher accuracy compared to linear and power-law regressions
  9. Keywords:
  10. Liquid Jet in Cross Flow (LJCF)Spray Structure ; Shadowgraphy Method ; Liquid Sheet ; Regression Analysis ; Data Science ; Sheet Injection

 Digital Object List

 Bookmark

No TOC