卫星推进系统气体流量探头的研制

介绍了卫星推进系统气体流量探头设计中的几个问题,该探头适用微波量气体流量的测量,采用了差压式孔板流量计的原理,设计轻巧,使用方便,能够进行远距离无失真传输,方便了现场测试。     

浅析提高标准节流装置在计量中的准确性

介绍柳钢使用的标准节流装置计量系统，并对设计、安装、维护的特点进行探讨，保证节流式流量计的正常运行。     

孔口倒圆角的编程方法

加工孔口倒圆角时，通常可以用成型刀来加工。但是当倒角半径比较特殊时用传统的方法加工就比较困难。文章通过举例的方式介绍了如何用普通立铣刀、球头刀，借助宏程序完成孔口倒圆角几种方法，并对加工效果进行比较。     

单气室油气悬架的阻尼特性分析

油气悬架对车辆的平稳性与动力性能有着非常重要的影响,油气悬架的性能主要通过它的阻尼特性来反映。以某一型号的矿用油气悬架为研究对象,利用有限元分析软件对其工作流场进行仿真与分析,得出了油气悬架在不同工况下的阻尼特性曲线,为油气悬架的优化设计提供参考依据。     

Development of an accurate method to prognosticate choke flow coefficients for natural gas flow through nozzle and orifice type chokes

One of the main components in oil and gas production system is choke valve. The choke valve role is maintaining sufficient back pressure to prevent water gas coning and formation damage and also stabilizing fluid flow to reach the optimum production scenario. Chokes can be employed either on surface or subsurface to control the fluid flow characteristics to the downstream processing facilities such as flow rate, pressure, and velocity. Malfunction of choke may results in severe damages in safety, facilities, and environment.In this study, a rigorous method based on artificial intelligence is developed to predict the choke flow coefficient for subsonic natural gas flow through nozzle and orifice type chokes. Reynolds number and ratio of choke diameter to pipe diameter was utilized as input parameters. The method used in this study is radial basis function neural network coupled with genetic algorithm. The results showed great agreement with experimental data. In addition, the proposed method was compared with classic correlations. This comparison demonstrated the robustness and superiority of the GA-RBF model.     

浅谈流量仪表的合理选型对能耗的分析与应用

本文从生产实际出发,提出生产中出现的问题,结合流量计选型时需要注意的事项,确定合理的选型方案,通过计算比较进一步验证合理选型对节能降耗的的重要性.     

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目前孔板流量计仍然在天然气计量中占主导地位。随着计算机、变送器和通讯等技术的发展，充分利用先进技术，使孔板流量计发挥其标准化程度高、研究深入的技术优势，实现天然气流量的自动计量是孔板流量计发展的必然趋势。根据目前孔板流量计实现天然气自动计量的多种模式，通过分析、比较，提出了选择最佳自动计量模式的6项原则: 数据的安全性原则; 计量回路的独立性原则; 使用操作的简单、可靠原则; 兼顾发展的原则；计算方法和计算软件的合法性原则; 技术先进、成熟的原则。并通过应用实例，说明了利用多变量变送器，采用一体化自成系统的计量仪表，利用现场总线技术，通过数字信号传输，实现多参数的实时补偿，组成真正意义上的集散控制系统，是科学、准确计量天然气流量的最佳方式。     

Effect of orifice shapes on the detonation transmission in 2H2–O2 mixture

In this study, the effect of orifice geometries on the detonation propagation is considered systematically in stoichiometric 2H₂–O₂ mixture. Three various orifice shapes with the same blockage ratio (BR = 0.889) are used firstly, i.e., round, square and triangular. Eight PCB pressure transducers are employed to obtain the average velocity through two adjacent signals while the smoked foil technique is used to record the detonation cellular pattern. The experimental results indicate that three different propagation modes can be observed: (1) when the initial pressure (P₀) is smaller than the critical value (P_c), the steady detonation wave cannot be produced before the orifice plate, afterwards, the mechanism of deflagration to detonation transition (DDT) is seen; (2) near the critical pressure, a steady detonation wave is formed prior to the obstacle, but the failure of detonation is seen after its propagation through the orifice plate due to the diffraction effect and the mass and momentum loss from the wall, and then the phenomenon of detonation re-initiation is observed due to the reflection from the wall; (3) at the initial pressure larger than the critical value, the steady detonation wave can propagate through the orifice plate without decay. Moreover, although the effect of orifice shapes on the critical pressure can be nearly ignored, the re-ignition position is different among three various orifice geometries. For the cases of round and square orifices, the ignition position is produced near the center of the wall. However, the detonation wave is re-ignited from the corner in the case of triangular orifice. Finally, the critical condition of detonation propagation can be quantified as D_H/λ > 1. But the critical values of D_H/λ are not uniform among three different orifice geometries. For the cases of round, square and triangular orifices, the critical values of D_H/λ are 8.94, 5.88 and 3.84, respectively.     

Experimental study on induced accelerated combustion of premixed hydrogen-air in a confined environment

The study on induced accelerated combustion of premixed hydrogen-air in a confined environment is of great significance for the efficient utilization of hydrogen energy in internal combustion engines. The accelerated flame induced by the orifice plate is more stable and easy to control, which is beneficial to achieve controlled and rapid turbulent combustion. In this work, the accelerated combustion process induced by the orifice plate, and the influence of the orifice structure and initial conditions on the flame propagation and combustion characteristics were investigated by constant volume combustion bomb and schlieren method. The results show that the combustion process induced by the orifice plate consists of three stages: the initial stage of propagation, the accelerated stage of the orifice plate, and the end combustion stage. The reduction in aperture induces greater turbulence intensity and increases the perturbation of the orifice plate to the flame, resulting in a substantial increase in flame propagation speed through the orifice plate. As the initial pressure and the equivalence ratio increase, the velocity of turbulent flame induced by the orifice plate and the change rate of the velocity before and after the orifice plate increase. As the initial temperature increases, the turbulent flame propagation velocity does not change much, and the velocity change rate before and after the orifice plate decreases. The effect of the initial conditions on flame acceleration induced by the orifice plate is essentially the influence of flame propagation speed and instability. The greater the flame propagation speed and the stronger the flame instability, the stronger the induced turbulence and the greater the influence of the turbulent flow disturbance, and the greater the velocity of the turbulent flame induced by the orifice plate. There exists an optimum aperture for the shortest combustion duration at any initial conditions, but the optimal diameter is not sensitive to changes in initial conditions. The effect of orifice-induced combustion acceleration is remarkable, and the combustion durations induced by each orifice plate are shortened by more than 50%.     

A flow control device for incompressible fluids

This paper introduces a constant flow method for incompressible fluids using a mechanical choked orifice plate (MCOP), even when changes in differential pressure occur between the upstream and downstream. The MCOP is constructed by inserting a float-spring blockage into an ordinary orifice plate to imitate the function of a critical cavitating flow in a cavitating Venturi. A model MCOP is established and verified by numerical simulation, and a prototype MCOP is designed and tested by experiments. The results show that the numerical simulation is a good guide for the MCOP design. The designed MCOP can keep a constant flow with an error in the flow control of ±4% within the range of the differential pressure between the upstream and downstream of 6–70 kPa. Because the constant flow is obtained without fluid vapourization, the pressure loss is greatly reduced and the noise and erosion are avoided. Additionally, due to the action of the float-spring blockage being based on the differential pressure between upstream and downstream, it is simultaneously insensitive to both upstream and downstream pressure fluctuations. The design idea and the conclusions can be used as a reference in the design of a constant flow control device for incompressible fluids.