TY - JOUR
T1 - Theoretical model of swirling thick film flow inside converging nozzles of various geometries
AU - Bang, Boo Hyoung
AU - Kim, Yong Il
AU - Ahn, Chan Sol
AU - Jeong, Seokgyu
AU - Yoon, Youngbin
AU - An, Seongpil
AU - Yoon, Sam S.
AU - Yarin, Alexander L.
N1 - Funding Information:
This work was supported by Advanced Research Center Program (NRF-2013R1A5A1073861) through the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) contracted through Advanced Space Propulsion Research Center at Seoul National University and NRF-2016M1A2A2936760.
PY - 2020/11/15
Y1 - 2020/11/15
N2 - Pressure-swirl jets are of paramount importance in such applications as liquid rockets, gas turbines, and internal combustion engines. Although the external spray has been extensively studied, the internal nozzle flow, which determines the external spray characteristics outside the nozzle, is relatively underexplored. Experimental studies of the internal nozzle flow are available, whereas theoretical approaches are less common, especially for strong swirl flows in which the boundary layer effect at the nozzle walls is significant. Herein, we explore a strongly swirling film flow, where viscous effects become dominant in the entire film and the boundary-layer approximation fails. The parabolized Navier-Stokes equations are solved by using the integral von Karman-Pohlhausen method, and the viscous liquid film flow over the entire nozzle wall is predicted including the central free surface configuration, the film characteristics such as its thickness, velocity components, and the spray cone angle, at the nozzle exit. The theoretical predictions are compared to the experimental data, and the dependence of the spray-cone angle on mass flow rate is experimentally validated. The theoretical parametric studies include the effect of the internal nozzle geometry, initial film thickness, the mass flow rate, and the effect of the swirling strength.
AB - Pressure-swirl jets are of paramount importance in such applications as liquid rockets, gas turbines, and internal combustion engines. Although the external spray has been extensively studied, the internal nozzle flow, which determines the external spray characteristics outside the nozzle, is relatively underexplored. Experimental studies of the internal nozzle flow are available, whereas theoretical approaches are less common, especially for strong swirl flows in which the boundary layer effect at the nozzle walls is significant. Herein, we explore a strongly swirling film flow, where viscous effects become dominant in the entire film and the boundary-layer approximation fails. The parabolized Navier-Stokes equations are solved by using the integral von Karman-Pohlhausen method, and the viscous liquid film flow over the entire nozzle wall is predicted including the central free surface configuration, the film characteristics such as its thickness, velocity components, and the spray cone angle, at the nozzle exit. The theoretical predictions are compared to the experimental data, and the dependence of the spray-cone angle on mass flow rate is experimentally validated. The theoretical parametric studies include the effect of the internal nozzle geometry, initial film thickness, the mass flow rate, and the effect of the swirling strength.
KW - Nozzle geometry
KW - Swirling jet
KW - Swirling strength
KW - The Reynolds number
KW - Thick film
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U2 - 10.1016/j.fuel.2020.118215
DO - 10.1016/j.fuel.2020.118215
M3 - Article
AN - SCOPUS:85088048284
VL - 280
JO - Fuel
JF - Fuel
SN - 0016-2361
M1 - 118215
ER -