基于3211多阶跃激励CFD模型的颤振导数识别研究

提出一种通过计算流体动力学(Computational Fluid Dynamics,CFD)建立离散时间气动模型并识别颤振导数的方法,该方法通过强迫模型按一种3211多阶跃方式运动,由CFD数值模拟得到作用在模型上的气动力。由于3211多阶跃包含了丰富的频率成份,能激励起气动力系统在这一连续频域范围内的广泛响应,因而可基于3211输入-气动力输出得到定义在某一频率范围的离散时间气动模型。该气动模型能对对应不同折算风速的简谐位移输入快速仿真得到气动力输出,通过这些输入-输出就可快速识别任意折算下的颤振导数,无需对不同折算风速重复进行CFD计算。应用本文方法识别了薄平板的颤振导数,并与薄平板风洞试验结果进行了比较,颤振导数的一致性证明了本文方法的有效性。

双阶跃JK触发器和多阶跃时序电路

本文首先分析双阶跃ＪＫ触发器完成的功能，推出它的特征方程，并设计其电路，然后用该触发器设计多阶跃时序电路。＊，当Ｓｄ＝Ｒｄ＝１时，得二、双阶跃ＪＫ触发器电路结构该触发器有置１和置０两个导引电路。先考虑置１导引电路，包括和基本触发器相互作用，图１（ａ）和（ｂ）是它的状态图和状态表，其中Ｑ和ｙ分别为基本触发器和导引电路状态变量，置１前Ｑ＝０，按Ｊ值状态在００和０１间转移。当ｃｐｊ↑来到时，若前瞬间Ｊ＝１，应产生置１脉冲（ｚ＝０），使Ｑ由０→１，即状态由０１→１１；反之，若Ｑ≠０或ｙ≠１，ｚ仍保持１．一旦Ｑ置１完成。将恢复ｚ＝１．此后ｙ再变化，Ｑ仍保持１．状态仅在１０和１１间转移。只有置０导引电路产生置０脉冲，才能使Ｑ复０．由图１（ｂ）画出图（ｃ）所示的卡诺图，由此得完备的含意是，该方程既能描述阶跃信号来到时触发的行为，又能描述阶跃信号未来到时触发器的行为，此外，还可描述异步置０置１功能。图１置１导引电路状态图２双阶跃触发器电路由式（５）画出半个触发器门级电路图，示如图２（α），按对称性画出图（ｂ）所示的整个触发器门级电路图。图（ｃ）是元件电路图，所用晶体管数与常用ＪＫ触发器相近当两阶跃之一来到，另一恒定（高、低?

Dynamic test on waste heat recovery system with organic Rankine cycle

Dynamic performance is important to the controlling and monitoring of the organic Rankine cycle(ORC) system so to avoid the occurrence of unwanted conditions. A small scale waste heat recovery system with organic Rankine cycle was constructed and the dynamic behavior was presented. In the dynamic test, the pump was stopped and then started. In addition, there was a step change of the flue gas volume flow rate and the converter frequency of multistage pump, respectively. The results indicate that the working fluid flow rate has the shortest response time, followed by the expander inlet pressure and the expander inlet temperature.The operation frequency of pump is a key parameter for the ORC system. Due to a step change of pump frequency(39.49-35.24 Hz),the expander efficiency and thermal efficiency drop by 16% and 21% within 2 min, respectively. Besides, the saturated mixture can lead to an increase of the expander rotation speed.