利用微波暗室、矢量网络分析仪、角锥喇叭天线以及电脑等设备建立了一套喇叭天线测量系统;采用两相同天线法,分别测量了4~6 GHz、6~8 GHz角锥喇叭天线的增益值,对测量数据进行误差分析和近距修正;并将增益的实测值与理论计算值进行对比...利用微波暗室、矢量网络分析仪、角锥喇叭天线以及电脑等设备建立了一套喇叭天线测量系统;采用两相同天线法,分别测量了4~6 GHz、6~8 GHz角锥喇叭天线的增益值,对测量数据进行误差分析和近距修正;并将增益的实测值与理论计算值进行对比。实验结果表明,近距修正后,所测量的4~6 GHz与6~8 GHz频段天线的增益实测值与理论值的最大偏差值分别为-0.20 d B和-0.19 d B,均在±0.25 d B范围内,符合标准增益天线增益的精度要求,也与天线出厂的指标相符,表明所建立的测量系统对于喇叭天线增益的测量有效可行。展开更多
Spark discharge plasma synthetic jets(SPJs) have been used for the active flow control study on an NACA 0021 straight-wing model in a wind tunnel. The model forces and moments were measured using a six-component sting...Spark discharge plasma synthetic jets(SPJs) have been used for the active flow control study on an NACA 0021 straight-wing model in a wind tunnel. The model forces and moments were measured using a six-component sting balance at a 20 m/s wind speed. The aim was to explore the SPJ's effect on airfoil aerodynamic by examining SPJ generators' position along the chordwise and the jet flow direction about the chord. Near the wing leading edge, two SPJ generators raised the stall angle by 2° and increased the maximum lift coefficient by 9%. The drag coefficient was decreased by 33.1%, and the lift-drag ratio was increased by 104.2% at an angle of attack above 16°. The rolling-moment coefficient was modified by 0.002, and the yawing-moment coefficient was changed by 0.0007 at angles of attack in the range of 0°–16°. The results showed that SPJs can control wing aerodynamic forces at a high angle of attack and moments at a low angle of attack.展开更多
文摘利用微波暗室、矢量网络分析仪、角锥喇叭天线以及电脑等设备建立了一套喇叭天线测量系统;采用两相同天线法,分别测量了4~6 GHz、6~8 GHz角锥喇叭天线的增益值,对测量数据进行误差分析和近距修正;并将增益的实测值与理论计算值进行对比。实验结果表明,近距修正后,所测量的4~6 GHz与6~8 GHz频段天线的增益实测值与理论值的最大偏差值分别为-0.20 d B和-0.19 d B,均在±0.25 d B范围内,符合标准增益天线增益的精度要求,也与天线出厂的指标相符,表明所建立的测量系统对于喇叭天线增益的测量有效可行。
文摘Spark discharge plasma synthetic jets(SPJs) have been used for the active flow control study on an NACA 0021 straight-wing model in a wind tunnel. The model forces and moments were measured using a six-component sting balance at a 20 m/s wind speed. The aim was to explore the SPJ's effect on airfoil aerodynamic by examining SPJ generators' position along the chordwise and the jet flow direction about the chord. Near the wing leading edge, two SPJ generators raised the stall angle by 2° and increased the maximum lift coefficient by 9%. The drag coefficient was decreased by 33.1%, and the lift-drag ratio was increased by 104.2% at an angle of attack above 16°. The rolling-moment coefficient was modified by 0.002, and the yawing-moment coefficient was changed by 0.0007 at angles of attack in the range of 0°–16°. The results showed that SPJs can control wing aerodynamic forces at a high angle of attack and moments at a low angle of attack.
