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Jet sweeping angle control by fluidic oscillators with master-slave designs
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作者 Ziyan LI Kaiwen ZHOU +1 位作者 Yingzheng LIU Xin WEN 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2021年第5期145-162,共18页
The fluidic oscillator is an instrument that can continuously generate a spatially sweeping jet entirely based on its internal geometry without any moving parts.However,the traditional fluidic oscillator has an inhere... The fluidic oscillator is an instrument that can continuously generate a spatially sweeping jet entirely based on its internal geometry without any moving parts.However,the traditional fluidic oscillator has an inherent limitation,that is,the spreading angle cannot be controlled independently,rather by the jet volume flow rate and internal geometry.Accordingly,two types of fluidic oscillators based on the master-slave design are developed in current study to decouple this correlation.In both designs,the master layer inherits the similar oscillation mechanisms of a sweeping jet,and the slave layer resembles a steady jet channel.The difference between the two designs is that Design A has a short diverging exit in the slave layer,but Design B adds a long interaction chamber in the exit channel to intensify flow instability.The external flow fields and governing oscillation properties of these two designs are experimentally explored with time-resolved Particle Image Velocimetry(PIV),while the internal flow dynamics and driving oscillation mechanisms are numerically investigated.By fixing the total volume flow rate,the jet spreading angle of Design A can be increased smoothly from 0°to above 100°by increasing the proportion of master layer’s flow rate from 0 to 100%.For Design B,the control authority of the master layer is significantly enhanced by adding the interaction chamber in the slave layer.In addition,the added chamber causes notable jet oscillation even when the master layer has none input. 展开更多
关键词 Adjustable spreading angle CFD Fluidic devices Master-slave fluidic oscillator TR-PIV
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Effects of Spatial Characteristics on Smart Antenna System with Uniform Linear Antenna Array 被引量:3
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作者 CAO Wei feng WANG Wen-bo 《The Journal of China Universities of Posts and Telecommunications》 EI CSCD 2005年第4期48-52,共5页
The effect of the spatial characteristics of antenna array on smart antenna systems can not be neglected. In the paper, the relation between spatial correlation and inter-antenna distance, impinging angle, angle sprea... The effect of the spatial characteristics of antenna array on smart antenna systems can not be neglected. In the paper, the relation between spatial correlation and inter-antenna distance, impinging angle, angle spread is first investigated. With the same beam forming algorithm, we simulate the performance of smart antenna system with different Angle Spread (AS) values on the conditions of ideal and real Angle of Arrival (AOA) estimation. The results show that with the ideal AOA estimation, the AOA is enough accurate to guarantee that the system only has little performance degradation even in the case of 20 degreee AS value while the real AOA estimation influenced by channel environment degrades the performance very obviously, up to about 7 dB. 展开更多
关键词 angle spread smart antenna uniform linear antenna array
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