GENERATION AND SHOCK WAVE CHARACTERISTICS OF UNSTEADY PULSED SUPERSONIC LIQUID JETS

2003 ◽  
Vol 13 (5-6) ◽  
pp. 475-498 ◽  
Author(s):  
K. Pianthong ◽  
B. E. Milton ◽  
M. Behnia
Shock Waves ◽  
2002 ◽  
Vol 11 (6) ◽  
pp. 457-466 ◽  
Author(s):  
K. Pianthong ◽  
S. Zakrzewski ◽  
M. Behnia ◽  
B.E. Milton

2017 ◽  
Vol 139 (12) ◽  
Author(s):  
Xinguo Lei ◽  
Mingxu Qi ◽  
Harold Sun ◽  
Liangjun Hu

Radial flow variable nozzle turbine (VNT) enables better matching between a turbocharger and engine and can improve the engine performance as well as decrease the engine emissions, especially when the engine works at low-end operation points. With increased nozzle loading, stronger shock wave and clearance leakage flow may be generated and consequently introduces strong rotor–stator interaction between turbine nozzle and rotor, which is a key concern of rotor high-cycle fatigue (HCF) failure. With the purpose of developing a low shock wave intensity turbine nozzle, the influence of grooved vane on the shock wave characteristics is investigated in the present paper. A Schlieren visualization experiment was first carried out on a linear turbine nozzle with smooth surface and the behavior of the shock wave was studied. Numerical simulations were also performed on the turbine nozzle. Guided by the visualization and numerical simulation, grooves were designed on the nozzle surface where the shock wave was originated and numerical simulations were performed to investigate the influence of grooves on the shock wave characteristics. Results indicate that for a smooth nozzle configuration, the intensity of the shock wave increases as the expansion ratios increase, while the onset position is shifted downstream to the nozzle trailing edge. For a nozzle configuration with grooved vane, the position of the shock wave onset is shifted upstream compared to the one with a smooth surface configuration, and the intensity of the shock wave and the static pressure (Ps) distortion at the nozzle vane exit plane are significantly depressed.


2019 ◽  
Vol 864 ◽  
pp. 1058-1087 ◽  
Author(s):  
Wangxia Wu ◽  
Bing Wang ◽  
Gaoming Xiang

The high-speed impingement of hollow droplets embedded with a cavity has fundamental applications in various scenarios, such as in spray coating and biomedical engineering. The impingement dynamics is modulated by the wrapping medium, different from that of denser solid droplets. With air and vapour cavities, the impingement of two kinds of hollow cylindrical droplets is simulated in the present study to investigate the morphology and physical mechanisms regarding droplet and cavity dynamics. The compressible two-phase Eulerian model is used to couple with the phase transition procedure. The results detail the evolution of droplets and collapsing dynamics of the two kinds of cavities. Processes are captured in which the impinging water-hammer shock wave interacts with the cavity, and vertical liquid jets are induced to impact the embedded cavity. For the case of the air cavity, a transmitted shock wave is formed and propagates inside the cavity. The air cavities are compressively deformed and broken into a series of small cavities. Subsequently, a range of intermittent collapsing compression wavelets are generated due to the interface collapse driven by local jets. As for the vapour cavity in the saturated state, initially, once it is impacted by the impinging shock wave, it gradually shrinks accompanied by local condensation but without generation of transmitted waves. Following the first interaction between the lower and upper surfaces of the cavity, the vapour cavity undergoes continuous condensation and collapse with repeated interface fusion. The vapour cavity finally turns into liquid water blended into the surroundings, and the strong collapsing shock waves are expanded inside the droplet. The radius ratios and initial impinging speeds are chosen to analyse the variation of the collapsing time, maximum collapsing pressure and mean pressure on the rigid wall. The pressure withstood by the wall due to the collapsing cavity increases with the initial size of the cavity and initial impinging speed. The maximum local pressures in the entire fluids and the mean pressure on the wall during the collapsing of the vapour cavities are higher than those for the air cavities.


2017 ◽  
Vol 140 ◽  
pp. 284-292 ◽  
Author(s):  
Xianggeng Wei ◽  
Rui Xue ◽  
Fei Qin ◽  
Chunbo Hu ◽  
Guoqiang He

Author(s):  
Xinguo Lei ◽  
Mingxu Qi ◽  
Harold Sun ◽  
Leon Hu

Radial flow Variable Nozzle Turbine (VNT) enables better matching between a turbocharger and engine, and can improve the engine performance as well as decrease the engine emissions, especially when the engine works at low-end operation points. With increased nozzle loading, stronger shock wave and clearance leakage flow may be generated. The shock wave consequently introduces strong rotor-stator interaction between turbine nozzle and impeller, which is also a key concern of impeller high cycle fatigue failure. With the purpose of developing a shock wave free or low shock wave intensity turbine nozzle, the influence of grooved vane on the shock wave characteristics is investigated in present paper. A Schlieren visualization experiment was first carried out on a linear turbine nozzle with smooth surface and the behavior of the shock wave was studied. Numerical simulations were also performed on the turbine nozzle. The predicted shock wave shape, position and intensity were compared against the Schlieren images. Guided by the visualization and numerical simulation, grooves were designed on the nozzle surface where the shock wave was originated and numerical simulations were performed to investigate the influence of grooves on the shock wave characteristics. Results indicate that for a smooth nozzle configuration, the intensity of the shock wave increases as the expansion ratios increase, while the onset position is shifted downstream to the nozzle trailing edge. For a nozzle configuration with grooved vane, the position of the shock wave onset is shifted upstream compared to the one with a smooth surface configuration, and the intensity of the shock wave as well as the static pressure distortion at the nozzle vane exit plane are significantly depressed.


2020 ◽  
Vol 53 (19) ◽  
pp. 195502 ◽  
Author(s):  
Guofeng Yin ◽  
Huantong Shi ◽  
Yunfei Fan ◽  
Jian Wu ◽  
Xingwen Li ◽  
...  

2018 ◽  
Vol 46 (7) ◽  
pp. 2591-2598 ◽  
Author(s):  
Qiaojue Liu ◽  
Yongmin Zhang ◽  
Aici Qiu ◽  
Weibo Yao ◽  
Haibin Zhou ◽  
...  

Sign in / Sign up

Export Citation Format

Share Document