Shock Control Method for Hypersonic Inlets Based on Forebody Secondary Flow Recirculation

AIAA Journal ◽  
2018 ◽  
Vol 56 (6) ◽  
pp. 2124-2130
Author(s):  
Yue Zhang ◽  
Hui-Jun Tan ◽  
Hao Chen ◽  
Wan-Ning Gao ◽  
He-Xia Huang
Keyword(s):  
Secondary Flow ◽  
Control Method ◽  
Flow Recirculation ◽  
Shock Control ◽  
Hypersonic Inlets

Investigation of a Fluidic Shock Control Method for Hypersonic Inlets

2010 ◽  
Vol 26 (5) ◽  
pp. 1072-1083 ◽  
Author(s):  
Hui-Jun Tan ◽  
Cheng-Hong Li ◽  
Yue Zhang
Keyword(s):  
Control Method ◽  
Shock Control ◽  
Hypersonic Inlets

Influence of Secondary Flow Injection Angle on a Fluidic Shock Control Technique

2015 ◽  
Vol 31 (2) ◽  
pp. 674-684 ◽  
Author(s):  
Cheng-hong Li ◽  
Hui-jun Tan ◽  
De-peng Wang
Keyword(s):  
Secondary Flow ◽  
Flow Injection ◽  
Control Technique ◽  
Injection Angle ◽  
Shock Control

SIMULATION OF VESSEL STRESS AND SECONDARY FLOWS FOR BLOOD FLOWS THROUGH A REALISTIC AORTA WITH THREE BRANCHES

2007 ◽  
Vol 19 (04) ◽  
pp. 215-223 ◽  
Author(s):  
Yang-Yao Niu ◽  
Pang-Chung Wu ◽  
Wen-Yih I. Tseng ◽  
Hsi-Yu Yu
Keyword(s):  
Secondary Flow ◽  
Aortic Arch ◽  
Three Dimensional ◽  
Wall Stress ◽  
Outer Wall ◽  
Secondary Flows ◽  
Blood Flows ◽  
Flow Recirculation ◽  
Dimensional Reconstruction

Blood secondary flows and vessel wall shear stress distributions in a human aortic arch have been predicted numerically for a Reynolds number of 4700 at entrance. The simulation geometry was derived from a three-dimensional reconstruction of a series of two-dimensional slices obtained in vivo. Numerical results demonstrate wall stresses were highly dynamic, but were generally high along the outer wall in the vicinity of the branches and low along the inner wall, particularly in the descending thoracic aorta. The maximum wall stress distribution is presented on the aortic arch in the systole. Extensive secondary flow motion was observed in the aorta, and the structure of these secondary flows was influenced considerably by the presence of the branches. Within the aorta, it is observed that clockwise secondary flow recirculation, also seen in the MRA scan data, appears in the downstream of aortic arch in the late systole and turn out to be a pair of counter-clockwise vortex in the downstream of the arch in the early diastole.

Fluidic Control Method for Improving the Self-Starting Ability of Hypersonic Inlets

2016 ◽  
Vol 32 (1) ◽  
pp. 153-160 ◽  
Author(s):  
Jian-Yong Wang ◽  
Lv-Rong Xie ◽  
Hao Zhao ◽  
Yu-Lin Teng ◽  
Guang-Fu Ma
Keyword(s):  
Control Method ◽  
The Self ◽  
Fluidic Control ◽  
Hypersonic Inlets

Investigation of adaptive slot control method for starting characteristics of hypersonic inlets

2018 ◽  
Vol 233 (11) ◽  
pp. 4261-4271
Author(s):  
Chengxiang Zhu ◽  
Rijiong Yang ◽  
Rongqian Chen ◽  
Ruofan Qiu ◽  
Yancheng You
Keyword(s):  
Mach Number ◽  
Pressure Gradient ◽  
Control Method ◽  
Separation Bubble ◽  
Substantial Reduction ◽  
Separation Shock ◽  
Hypersonic Inlet ◽  
The Individual ◽  
Starting Characteristics ◽  
Hypersonic Inlets

Starting characteristics restrict the operation limits of a hypersonic inlet. Enhancement of the starting ability thus serves as one of the most serious issues in propulsion system. In the present work, we propose a simple adaptive slot control method, which expands the working range of hypersonic inlets to a lower Mach number and shows very weak losses. Our simulation results applying the five parallel slot geometrical design show a substantial reduction of the starting Mach number. The air flow inside the parallel slot channels is self-driven by the pressure gradient located near the separation shock under unstart mode, whereas it is strongly suppressed when the inlet is restarted. Surprisingly, all the inlet configurations are almost restarted at the same Mach 3.0, regardless of the individual width of the slot and the number of slot. This confirms the self-adapted nature of the pressure gradient inside the channel which shows prospect for the potential engineering applications of the simple slot control method. However, the location of the slots shows a big influence on the control efficiency, indicating that these slots need to be arranged carefully on the compression surface based on the location of the separation bubble.

Performance enhancing for a highly loaded tandem cascade by endwall incoming vortex–corner separation interaction

2021 ◽  
pp. 095440622110187
Author(s):  
Zhiyuan Cao ◽  
Xi Gao ◽  
Cheng Song ◽  
Xiang Zhang ◽  
Fei Zhang ◽  
...  
Keyword(s):  
Secondary Flow ◽  
Control Method ◽  
Leading Edge ◽  
Control Effect ◽  
Suction Surface ◽  
Blade Passage ◽  
Corner Separation ◽  
Pressure Surface ◽  
Passage Vortex ◽  
Highly Loaded

In highly loaded tandem compressor cascades, corner separations can still exist. In order to eliminate corner separations in highly loaded tandem compressor cascades, incoming vortex–corner separation interaction mechanism was investigated. Different schemes of the vortex generators, which located at different pitchwise locations and could generate vortexes with different rotation directions, were designed and investigated numerically. Results show that, severe corner separation occurred at the front blade passage of the tandem cascade; by utilizing flow control method of incoming vortex–corner separation interaction, the corner separation could be reduced significantly. The optimal control effect of incoming vortex on corner separation was achieved with anticlockwise rotation and the vortex generator is located right ahead of the leading edge of tandem cascade, a maximum loss coefficient reduction of 21.8% being achieved. Different from single blade configuration, the boundary layer of tandem cascade was regenerated at rear blade suction surface due to the injection flow from blade gap between the two blades. Though corner separations could be reduced at both conditions, the loss of tandem cascade with clockwise incoming vortex is higher than that with anticlockwise vortex, and a smaller corner separation region at suction surface was achieved by utilizing clockwise vortex. The mechanism was that anticlockwise incoming vortex reduced the corner separation but increased secondary flow, while clockwise vortex enhanced passage vortex and decreased secondary flow. For clockwise incoming vortex near pressure surface, the vortex would be divided into two parts at the leading edge of rear blade, one would go through the blade gap and deteriorate flow fluid near rear blade suction surface, the other flowed downstream along pressure surface. The rotation direction of different incoming vortexes became the same as the passage vortex at rear blade passage of tandem cascade, which was mainly due to the effect of secondary flow.

Flow Control Investigations of Steady and Pulsed Jets in Bowed Compressor Cascades

2016 ◽  
Author(s):  
Longting Li ◽  
Yanping Song ◽  
Fu Chen ◽  
Huaping Liu
Keyword(s):  
Flow Control ◽  
Secondary Flow ◽  
Control Method ◽  
Vortex Generator ◽  
Actuation Frequency ◽  
Single Vortex ◽  
Pulsed Jets ◽  
Blowing Ratio ◽  
Passage Vortex ◽  
Flow Loss

Based on the previous research about the combined flow control method which was carried out by applying the endwall steady VGJ to the bowed compressor cascades to reduce the secondary flow loss, for the consideration that the pulsed jets may save the mass flow required for control, therefore the unsteady VGJs over the different actuation frequencies and blowing ratios were investigated in detail. Under the conditions of same jet geometry parameters, the improvements to the fluid fields in the bowed compressor cascades caused by the pulsed jets are less than that induced by the steady cases. With the pulsed VGJ, for the positively bowed blade, the enhancement of the time-averaged aerodynamic performance can be achieved when the blowing ratio is greater than 0.6, but all of the unsteady conditions in this research can improve the flow field in the negatively bowed blade. The time-averaged total losses decrease by 1.6% and 7.0% at most for the positively and negatively bowed blades, respectively. The mechanisms by which the endwall pulsed vortex generator jets delay flow separation and reduce loss were explored. The results show that, being different from the single vortex produced in steady VGJ, the pulsed case generates a pair of streamwise vortices with the opposite sense of rotation. One vortex suppresses the development of the secondary flow, but the other one increases the size of the passage vortex. Furthermore, for the endwall pulsed VGJ, the changes of the blowing ratio plays a more important role in improving the flow fields in the bowed cascades than that of the actuation frequency.

A distributed access control method for wireless LANs in shadowing environments

2001 ◽  
Vol 84 (9) ◽  
pp. 16-26
Author(s):  
Tadao Saito ◽  
Hitoshi Aida ◽  
Terumasa Aoki ◽  
Soichiro Hidaka ◽  
Tredej Toranawigtrai ◽  
...  
Keyword(s):  
Access Control ◽  
Control Method ◽  
Wireless Lans ◽  
Distributed Access Control
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