Aiming at the dynamic stall problem that restricts the improvement of aircraft maneuverability,a new dynamic stall control method based on leading-edge Dual Synthetic Jets(DSJ)is proposed in this paper.The aerodynamic...Aiming at the dynamic stall problem that restricts the improvement of aircraft maneuverability,a new dynamic stall control method based on leading-edge Dual Synthetic Jets(DSJ)is proposed in this paper.The aerodynamic control characteristics and flow field evolution process of steady jet,Synthetic Jet(SJ)and DSJ in dynamic stall flow field are analyzed in detail,and the corresponding control mechanism is revealed.The strong"wall attachment effect"and quasisteady"characteristics of DSJ are found.The results show that the leading-edge jet technology can improve the dynamic stall flow field environment.For the whole pitching process,the average lift coefficients of steady jet,SJ and DSJ increased by 3.65%,10.51%and 14.62%respectively,and the average drag coefficients decreased by 9.58%,29.9%and 32.0%respectively.In the downward phase,the average lift coefficient increased by 16.31%,26.72%and 35.88%respectively,and the average drag coefficient decreased by 26.21%,50.46%and 54.28%respectively.Due to its strong"wall attachment effect"and"quasi-steady"characteristics,DSJ exhibits optimal control effect,showing its application potential in dynamic stall control.展开更多
双电源配电环网是实现配电网故障无缝自愈、有效解决短时停电问题的基础,但配电环网中潮流呈自然分布,且缺乏有效的调节手段,统一潮流控制器(unified power flowcontroller,UPFC)可对环网潮流进行控制,但需突破其经济性瓶颈。为此,在调...双电源配电环网是实现配电网故障无缝自愈、有效解决短时停电问题的基础,但配电环网中潮流呈自然分布,且缺乏有效的调节手段,统一潮流控制器(unified power flowcontroller,UPFC)可对环网潮流进行控制,但需突破其经济性瓶颈。为此,在调节功率一定时,以负荷节点电压与环网两端馈线出力极限为约束条件,分别以UPFC输出的有功功率和视在功率最小为目标,提出了潮流控制策略。仿真结果表明2种优化控制策略能够满足配电环网潮流调度要求,且兼顾了UPFC应用的经济性。展开更多
Thrust vectoring technology plays an important role in improving the maneuverability of aircraft.In order to overcome the disadvantages of mechanical thrust vectoring nozzles,such as complications of structure and sig...Thrust vectoring technology plays an important role in improving the maneuverability of aircraft.In order to overcome the disadvantages of mechanical thrust vectoring nozzles,such as complications of structure and significant increases in weight and cost,fluidic thrust vectoring noz-zles are proposed.Dual Throat fluidic thrust vectoring Nozzle(DTN)has received wide attention due to its excellent thrust vectoring efficiency and minimal thrust loss.In this study,three-dimensional unsteady numerical simulations of a single axisymmetric DTN are conducted first to analyze its dynamic response.Then the pitch and yaw control characteristics of DTN equipped on a flying-wing aircraft are investigated.It is found that the dynamic response will experience three stages:rapid-deflecting stage,oscillating stage,and steady stage.A complete recirculation zone forms at the end of the rapid-deflecting stage,which pushes the primary flow to attach to the wall opposite the secondary injection.Meanwhile,the exhaust flow is deflected.In terms of DTN's appli-cation,the DTN equipped on the flying-wing aircraft is capable of providing effective pitch and yaw moments at all angles of attack and Mach numbers.In addition,continuous pitch and yaw moments can be obtained by adjusting the secondary mass flow ratios.The control moment is gen-erated due to the asymmetrical pressure distribution of nozzle surface,which is mainly contributed by the pressure decrease on the secondary injection surface.Moreover,the DTN equipped on the flying-wing aircraft has a relatively high thrust vectoring efficiency of around 5°/%and a thrust coefficient of around 0.95 when nozzle pressure ratio equals 4.These results provide an important theoretical basis for the practical application of DTN.展开更多
鞍钢股份能源管控中心汽机作业区一期前置背压式发电机组减温减压器(RTP)在运行热备过程中,发生漏量大导致高品位能源损失、发电量减少的故障,经过精确的热力计算找到问题存在的基础数据,并对减温减压器(RTP)的减温水系统进行改造,改造...鞍钢股份能源管控中心汽机作业区一期前置背压式发电机组减温减压器(RTP)在运行热备过程中,发生漏量大导致高品位能源损失、发电量减少的故障,经过精确的热力计算找到问题存在的基础数据,并对减温减压器(RTP)的减温水系统进行改造,改造后机组发电量每小时提高2564 k W。并进一步发展和完善了减温减压器(RTP)小流量调节技术。展开更多
In this paper, an interline power flow controller （IPFC） is used for controlling multi transmission lines. However, the optimal placement of IPFC in the transmis-sion line is a major problem. Thus, we use a combinat...In this paper, an interline power flow controller （IPFC） is used for controlling multi transmission lines. However, the optimal placement of IPFC in the transmis-sion line is a major problem. Thus, we use a combination of tabu search （TS） algorithm and artificial neural network （ANN） in the proposed method to find out the best placement locations for IPFC in a given multi transmission line system. TS algorithm is an optimization algorithm and we use it in the proposed method to determine the optimum bus combination using line data. Then, using the optimum bus combination, the neural network is trained to find out the best placement locations for IPFC. Finally, IPFC is connected at the best locations indicated by the neural network. Furthermore, using Newton-Raphson load flow algorithm, the transmission line loss of the IPFC connected bus is analyzed. The proposed methodology is implemen- ted in MATLAB working platform and tested on the IEEE-14 bus system. The output is compared with the genetic algorithm （GA） and general load flow analysis. The results are validated with Levenberg-Marquardt back propagation and gradient descent with momentum network training algorithm.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52075538,92271110)Hunan Provincial Natural Science Foundation,China(No.2023JJ30622)the National Science and Technology Major Project,China(Nos.J2019-II-0016-0037,J2019-III-0010-0054).
文摘Aiming at the dynamic stall problem that restricts the improvement of aircraft maneuverability,a new dynamic stall control method based on leading-edge Dual Synthetic Jets(DSJ)is proposed in this paper.The aerodynamic control characteristics and flow field evolution process of steady jet,Synthetic Jet(SJ)and DSJ in dynamic stall flow field are analyzed in detail,and the corresponding control mechanism is revealed.The strong"wall attachment effect"and quasisteady"characteristics of DSJ are found.The results show that the leading-edge jet technology can improve the dynamic stall flow field environment.For the whole pitching process,the average lift coefficients of steady jet,SJ and DSJ increased by 3.65%,10.51%and 14.62%respectively,and the average drag coefficients decreased by 9.58%,29.9%and 32.0%respectively.In the downward phase,the average lift coefficient increased by 16.31%,26.72%and 35.88%respectively,and the average drag coefficient decreased by 26.21%,50.46%and 54.28%respectively.Due to its strong"wall attachment effect"and"quasi-steady"characteristics,DSJ exhibits optimal control effect,showing its application potential in dynamic stall control.
文摘双电源配电环网是实现配电网故障无缝自愈、有效解决短时停电问题的基础,但配电环网中潮流呈自然分布,且缺乏有效的调节手段,统一潮流控制器(unified power flowcontroller,UPFC)可对环网潮流进行控制,但需突破其经济性瓶颈。为此,在调节功率一定时,以负荷节点电压与环网两端馈线出力极限为约束条件,分别以UPFC输出的有功功率和视在功率最小为目标,提出了潮流控制策略。仿真结果表明2种优化控制策略能够满足配电环网潮流调度要求,且兼顾了UPFC应用的经济性。
基金supported by the National Natural Science Foundation of China (Nos.U2141253 and 11721202).
文摘Thrust vectoring technology plays an important role in improving the maneuverability of aircraft.In order to overcome the disadvantages of mechanical thrust vectoring nozzles,such as complications of structure and significant increases in weight and cost,fluidic thrust vectoring noz-zles are proposed.Dual Throat fluidic thrust vectoring Nozzle(DTN)has received wide attention due to its excellent thrust vectoring efficiency and minimal thrust loss.In this study,three-dimensional unsteady numerical simulations of a single axisymmetric DTN are conducted first to analyze its dynamic response.Then the pitch and yaw control characteristics of DTN equipped on a flying-wing aircraft are investigated.It is found that the dynamic response will experience three stages:rapid-deflecting stage,oscillating stage,and steady stage.A complete recirculation zone forms at the end of the rapid-deflecting stage,which pushes the primary flow to attach to the wall opposite the secondary injection.Meanwhile,the exhaust flow is deflected.In terms of DTN's appli-cation,the DTN equipped on the flying-wing aircraft is capable of providing effective pitch and yaw moments at all angles of attack and Mach numbers.In addition,continuous pitch and yaw moments can be obtained by adjusting the secondary mass flow ratios.The control moment is gen-erated due to the asymmetrical pressure distribution of nozzle surface,which is mainly contributed by the pressure decrease on the secondary injection surface.Moreover,the DTN equipped on the flying-wing aircraft has a relatively high thrust vectoring efficiency of around 5°/%and a thrust coefficient of around 0.95 when nozzle pressure ratio equals 4.These results provide an important theoretical basis for the practical application of DTN.
文摘鞍钢股份能源管控中心汽机作业区一期前置背压式发电机组减温减压器(RTP)在运行热备过程中,发生漏量大导致高品位能源损失、发电量减少的故障,经过精确的热力计算找到问题存在的基础数据,并对减温减压器(RTP)的减温水系统进行改造,改造后机组发电量每小时提高2564 k W。并进一步发展和完善了减温减压器(RTP)小流量调节技术。
文摘In this paper, an interline power flow controller （IPFC） is used for controlling multi transmission lines. However, the optimal placement of IPFC in the transmis-sion line is a major problem. Thus, we use a combination of tabu search （TS） algorithm and artificial neural network （ANN） in the proposed method to find out the best placement locations for IPFC in a given multi transmission line system. TS algorithm is an optimization algorithm and we use it in the proposed method to determine the optimum bus combination using line data. Then, using the optimum bus combination, the neural network is trained to find out the best placement locations for IPFC. Finally, IPFC is connected at the best locations indicated by the neural network. Furthermore, using Newton-Raphson load flow algorithm, the transmission line loss of the IPFC connected bus is analyzed. The proposed methodology is implemen- ted in MATLAB working platform and tested on the IEEE-14 bus system. The output is compared with the genetic algorithm （GA） and general load flow analysis. The results are validated with Levenberg-Marquardt back propagation and gradient descent with momentum network training algorithm.
