Active contour model (ACM) was developed to track spray angle of atomizer. Through debugging and testing

ACM successfully captured the boundary of atomizer spray. The feature of spray contraction at downstream part of spray was also obtained

and spray angle was got exactly. The verification results show that

the relative errors between the spray angle values measured by the ACM tracking and the shadowgraph measurement are less than 1.5%. The ACM tracking spray angle can reduce cost of engineering applications with an identical measuring accuracy.