Investigation On The Flow Characteristics Of Pressure Swirl Atomizer

The pressure swirl atomizers which can change fuel into sprays are widely used in gas turbine combustors.The performance of atomizers has direct effect on flame stability, combustion efficiency, and pollutant emissions. Many factors would influence its performance, in which internal flow characteristics play a very important role. Corresponding on this, this paper carried out research on flow characteristics and performance of simplex atomizer.This paper firstly carried out numerical research. After computational method researched, interface tracking method volume of fluid(VOF) was used to simulate the flow in a typical simplex atomizer. The flow field of simplex atomizer with different pressure drop, length of swirl chamber(Ls), diameter of swirl chamber(Ds), length of nozzle(lo), diameter of nozzle(do), area of inlet slot(Ap), spin chamber convergence angle(?c) were analyzed and their atomization performance were acquired. Besides, large scale atomizers were simulated and the results agree very well with experiment's results. It also show that the flow structure were approximately stable at high Re number.For the small scale of simplex atomizer and complex diagnostic technology, the experimental study is based on a big scale transparent simplex atomizer which designed in this paper. The tangential velocity profile in spin chamber, the axial velocity profile in spin chamber, discharge characteristics, spray angle, film thickness and Sauter Mean Diameter(SMD) are mesured. The results revels:(1) The tangential velocity in swirl chamber were increase at an exponential rate as radus decrease while the axial velocity profile show the axial flow were almost static at lagre radical position. With decrease of radus, the axial velocity suddently step to a high value and stay stable until air core boundary. This denote that the fuel were largely flow from air core radical position to exit nozzle in swirl chamber. Under experimental range, empirical formulas with diamensionless geometry parameter are established to describe tangential velocity in spin chamber.(2) The relationship between discharge coefficient, film thickness, spray angle, SMD and dimensionless geometry paraments are acquired under Ap/Dsdo change from 0.38 to1.05, Ds/do change from 3 to 7.5, Ls/Ds change from 0.57 to 1.33, lo/do change from 0.17 to 1. Beides, empirical formulas of discharge coefficient and spray angle are formed.(3) The pressure drop has little influence on discharge coefficient. With the increase of pressure drop, film thickness would decrease, while spray angle would increase and keep steady after reach maximum value. Besides, the tangential velocity and axial velocity would increase as pressure drop increase.There are some different between the the results of numerical simulation and experiment while the pattern are almost same. What has been done would further our understanding of underlying physics of flow in simplex atomizer and of great theoratical and practical value.