涡环

Aimming at the fuel control requirement of micro-turbojet,the automobile's electric fuel pump with adaptable improvement is chosen as fuel-feed system.The performance of fuel pump and the technical difficulty of flux control as the speed of pump doesn't be measured are analyzed.Using Philips 83C552 MCU as the main control chip,the system adopts voltage negative feedback combined current compensation instead of rotation speed negative feedback and a PWM convertor to design the flux closed loop control system.

针对微型涡喷发动机的燃油控制要求，选用汽车用电动油泵进行适应性改进作为供油执行装置，详细分析了电动油泵的特性及泵转速无法测量情况下流量控制的技术难点，并以83C552单片机为核心，采用电压负反馈加电流补偿代替转速负反馈、电机通过PWM驱动的方法设计电动油泵流量闭环控制系统。

Based on analysis of the current state of the flow pattern modeling abroad and at home, explains the meaning of the mathematical simulation of the flows in the valve.(2) Comparing flow simulation data of jet pump with its experimental one, the feasibility and reliability of FLUENT used for flow simulation are proved.(3) Based on the characteristic of valves, the fluid field analysis of specific ring-spray type flow-adjustable is finished. The valve structure is optimized to meet the need, which makes it have such advantages:(1)smaller vortex area and faintish vortex intensity, so the vibration of vortex is controlled effectively;(2)the pressure is distributed more equality, the transition area is larger.

论文的主要内容包括：(1)简述了阀门研究的现状与发展，在分析与总结国内外流体流动模拟研究的基础上，探讨开展阀门内水流运动数值模拟的意义；(2)对特定型号的射流泵进行了内部流场的数值模拟研究，并与实验数据相比较，验证了应用Fluent进行数值模拟的可行性和可靠性；(3)针对调流阀的特点，对特大口径环喷式流量调节阀进行流场计算，其设计指导思想如下： 1、控制旋涡，减小旋涡区，减小涡的强度； 2、控制压力分布，使阀体受力更均匀，改善局部应力状态，提高阀门使用的安全性； 3、最小绝对压力高于水的汽化压力，不产生汽蚀。

Dome stake-What do we know about this stake. Any specifications like you sent me on that one book? Paint- Is it lead free. Strength of the swirly loop thing at the top. What point will it break? Paint chips easily... what's up with that?

圆形顶树桩，我们知道这个树桩，就像你寄给我的那本书上的任何规格，颜料不含铅，顶部成涡形环，什么点它会倒，颜料很容易脱落，这是什么原因？

This paper deals with a lump-sum flow analysis of a spiral case, stay ring and vaneless annular walls for a small Francis tu...

本文对常用的小型混流式水轮机涡壳、座环和无导叶环壁面内流动状况用最新的 CFD技术进行了整体数值解析。

The experimental results showed that this dissertation has certain practical importance for qualitatively analyze draft tube pressure fluctuation.

对引起尾水管涡带压力脉动的转轮出口环量计算公式进行了简化，也对描述压力脉动两个主要特征参数频率和振幅的计算公式做了尝试性的简化推导，并且通过实例计算说明，本文所做的尝试性的工作，为定性分析尾水管涡带压力脉动特性有一定的实用价值。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。