工程机械气顶油行车制动系统的结构改进

正1.气顶油行车制动系统目前压路机、装载机、平地机等工程机械大都采用气顶油行车制动系统。该系统主要由发动机1、空压机2、安全阀3、油水分离器4、储气筒5、脚踏制动阀6、气顶油加力泵7、制动钳8组成,如图1所示。储气筒5上安装有安全阀3,当储气简5储气压力达到安全阀3设定压力值后,安全阀3向外排气,以保持设定压力值。制动时,压缩空气从储气筒5经脚踏制动阀6到达气顶油加力泵7。     

基于无量纲化思想的柔性恒压储气装置优化设计

针对柔性恒压储气装置储能特性与材料变形、结构尺度之间的复杂相关性,提出一种无量纲化的结构改进设计方法,以描述储气装置的压力及能量变化规律。从橡胶的本构模型着手,利用有限元仿真思想研究应变能转换机制,分析结构参数与储能特性之间的关系。搭建储气装置充放气试验台,针对不同结构参数及压力工况,进行储气装置的能量变化规律验证。采用仿真及实验相结合的方式,研究尺度变化对能量特性的影响规律。为优化储气装置结构以及应用方面的研究奠定了理论基础。     

降压节能与耗能

以压缩空气为介质的传动与控制系统中,气源压力一般总是高于使用压力。为了获得稳定的压力输出,满足控制系统中不同的压力等级,都通过减压阀降压。为了节省气缸运动所耗的能量,常采用高压送进、低压复位。当用气量太大时,设置低压气罐储气的话,因气罐容积太大,故常用高压气罐储气,使用时再将高压降为低压。这些高压     

某型车载气源设计

该文详细介绍了某型地面车载气源的设计原理、方法及内容。解决了用气问题。该车载气源可用一台设备同时给四个部件供气。车载气源集充气、储气、过滤、减压、输出及压力控制等诸多功能于一体,具有集成化程度高,体积小、重量轻、功能齐全、操做方便等特点。     

气体脉动试验系统研究

为了实现水锤波等多种波形控制,适用贵重或有毒介质的产品脉动试验需求,采用气体扩散平衡原理,通过伺服阀流量控制与反馈,结合多级压力储气容器的容积匹配设计,并通过增压及泄放复合方式,实现脉动频率可调。文中设计了一种适用于低于0.2 L试验腔体的脉冲试验系统,通过试验验证,在设定条件下,设备可实现100 000次可靠运行,设备噪声、波形拟合度均能满足压力传感器的脉动试验技术要求,且压力控制稳定。     

空压机压力超高故障及预防一例

我厂氮气生产单元的一台日产二级无油润滑式空气压缩机,其工作简意流程图如图所示。在使用中出现了一、二级出口压力超高的现象,严重影响了装置的正常运行、设备的使用寿命。     

大口径无缝钢瓶双轮旋压机

本文介绍了一种生产大口径无缝钢瓶的双轮旋压机,该设备最大加工外径可达Φ950mm,填补了国内外在此项技术和工艺领域的空白。该旋压机生产的Φ914无缝高压气瓶已成功运用到CNG站用储气领域和车载运输领域,与传统气瓶相比,大大提高了储气容积和气瓶的容重比,减少了连接管路和泄漏点,具有良好的市场前景。     

压缩空气储能系统的工作特性研究

基于典型压缩空气储能系统工作原理,运用热力学理论建立了压缩过程、储气系统和膨胀发电过程的理论分析模型。采用储能效率和储能密度作为评价指标,揭示了压缩空气储能系统在等温、绝热和多级多变工作过程下的工作特性,分析比较了恒压和恒容储气方式对有效能、储气罐容积等系统性能的影响规律。结果表明增大储气压力以及采用多级压缩和多级膨胀过程可提高储能系统的效率和储能密度。采用恒压式储气罐可减小储气容积。分析模型和研究结果可为设计高效的压缩空气储能系统循环形式提供基础。     

填充聚四氟乙烯用作无油润滑元件

一、前言无油润滑压缩机是现代空间技术、国防、化工、炼油、食品、化肥等工业中不可缺少的设备。在这些场合中,要求压缩气体必须纯净无油或只含微量油。例如:化肥厂采用汽提法或全循环法生产的尿素,其所用的二氧化碳压缩机就需要无油润滑. 二氧化碳压缩机实现出口气体无油或微油后,可简化设备,改善生产环境,保证安全生产,节约润滑     

基于AMESim的一种新型气、液耦合能源系统仿真分析

采用AMESim液压仿真软件建立了一种气、液耦合挤压式能源系统仿真模型,重点分析了该类系统初始储气压力、储气容积等参数对该类能源特性的影响,并对全伺服系统AMESim模型进行了系统级仿真分析,为该类系统提供了一种有效的设计方法。     

TRT顶压控制系统设计和仿真

高炉料柱的周期性变化是TRT装置顶压控制系统主回路中的主要扰动因素。该文提出了包括主、副回路的TRT顶压控制系统的整体改进方案,为TRT装置顶压控制系统设计了带前馈结构DMC的主回路控制算法。仿真结果表明,与普通DMC、普通PID和前馈PID算法相比,带有前馈结构的DMC控制器能够有效地抑制高炉料柱周期性变化对TRT装置高炉顶压的影响,且在模型失配时拥有良好的鲁棒性。     

A CFD study of wet gas metering over-reading model under high pressure

The venturi flow meter is increasingly being preferred in multiphase flow measurement because of its shorter upstream and downstream straight sections, less influenced by the flow pattern and relatively small pressure loss. However, when the venturi is used for wet gas measurement, the over-reading phenomenon occurs due to the presence of a small amount of liquid. Many scholars have established over-reading models to correct the measured values of wet gas. Regrettably, the applicability of these over-reading models under actual high pressure operating conditions has not been verified. Therefore, this review focuses on numerical simulation of the flow of wet gas in the venturi tube under high pressure conditions (11MPa/13MPa/15 MPa). The discrete phase model (DPM) and the standard k-ε model was employed in this review. The simulations results reveals the flow characteristics of wet gas in venturi tube, which includes the flow field distributions, droplet concentration distributions and wall pressure profile distributions, and indicates that the over-reading values increases with the increase of Lockhart-Martinelli parameters and gas volume flow rate, but decreases with the increase of pressure. Moreover, the ISO model has the best performance under high pressure conditions.     

Real gas effects on charging and discharging processes of high pressure pneumatics

The high pressure pneumatic system has been applied to special industries.It may cause errors when we analyze high pressure pneumatics under ideal gas assumption.However,the real gas effect on the performances of high pressure pneumatics is seldom investigated.In this paper,the real gas effects on air enthalpy and internal energy are estimated firstly to study the real gas effect on the energy conversion.Under ideal gas assumption,enthalpy and internal energy are solely related to air temperature.The estimation result indicates that the pressure enthalpy and pressure internal energy of real pneumatic air obviously decrease the values of enthalpy and internal energy for high pressure pneumatics,and the values of pressure enthalpy and pressure internal energy are close.Based on the relationship among pressure,enthalpy and internal energy,the real gas effects on charging and discharging processes of high pressure pneumatics are estimated,which indicates that the real gas effect accelerates the temperature and pressure decreasing rates during discharging process,and decelerates their increasing rates during charging process.According to the above analysis,and for the inconvenience in building the simulation model for real gas and the difficulty of measuring the detail thermal capacities of pneumatics,a method to compensate the real gas effect under ideal gas assumption is proposed by modulating the thermal capacity of the pneumatic container in simulation.The experiments of switching expansion reduction(SER) for high pressure pneumatics are used to verify this compensating method.SER includes the discharging process of supply tanks and the charging process of expansion tank.The simulated and experimental results of SER are highly consistent.The proposed compensation method provides a convenient way to obtain more realistic simulation results for high pressure pneumatics.     

高压气体压力及流量控制系统

构建了一个高压气体压力及流量控制系统。该系统的硬件部分主要由控制器、电磁比例阀、压力伺服阀、减压阀、截止阀、压力传感器、节流孔板等组成。软件部分由2个模块组成,其中压力控制模块以PI方法为基础,通过电磁比例阀、压力伺服阀实现对气体压力的控制;流量控制模块以PID方法为基础,根据压力差与流量之间的关系,通过控制节流孔板前后的压力差对流量进行较精确的控制。该系统已成功应用于工业生产中。     

Characterization of a fast gas analyzer based on Raman scattering for the analysis of synthesis gas

A sensor system for fast analysis of synthesis gas (mixtures of CO and H(2)) is proposed and characterized. The system is based on spontaneous Raman scattering, which enables simultaneous concentration measurements of all relevant species. For typical synthesis gas applications, this system has to face large variations of temperature and pressure. In addition, strong fluctuations in mixture composition may occur, which lead to rather inconvenient signal intensities. In this paper, we describe a low resolution spectrometer designed to function as a synthesis gas sensor and characterize pressure and temperature effects on concentration measurements. In addition, the use of different spectral ranges and calibration strategies is investigated in view of measurement accuracy and precision.     

页岩气井下开采管路气固耦合振动特性分析

页岩气开采过程中,井下管路内气体与管路的耦合作用,会引起管路振动,这是此类管路振动失效的主要原因。管路振动响应特性与井下管路长度、气体流速及压力等参数有直接关系,因此,研究这些参数的影响对揭示页岩气管路振动规律,提高井下管路安全性及寿命有重要意义。针对页岩气井下管路,在ADINA软件平台中建立有限元分析模型,进行振动模态分析,研究管路长度、气体流速及压力对管路气固耦合振动特性的作用规律。研究结果为页岩气井下管路振动实验研究提供理论指导,同时为气固耦合振动特性研究奠定基础。     

气体喷射压缩器变工况特性的理论研究

利用气体喷射压缩器几何结构参数、混合室动量方程、流动连续性方程、质量守恒方程以及气体动力函数等，补充推导出了工作压力变化对喷射系数、温度比变化对喷射系数的影响关系式，并以某一蒸汽喷射压缩器为实例，通过计算补充提供了工作压力、引射压力、工作温度、引射温度单因素变化时的变工况特性曲线，对于进一步掌握这些因素变化对气体喷射压缩器运行性能的影响规律以及对气体喷射压缩器的合理运行与调整很有意义。     

Wet gas pressure drop across orifice plate in horizontal pipes in the region of flow pattern transition

As a basis for measuring the mass flow rate of wet gas using differential pressure meters, predicting the pressure drop of a wet gas flowing through orifice plates is important; however, this has not yet been solved satisfactorily, although many studies have reported on that subject. In this study, the pressure drop of wet gas across sharp-edged orifice plates was experimentally investigated in the region of flow pattern transition using air and water as the two phases, and the prediction performance of the available pressure drop models was compared based on the experimental data. The results show that the homogenous flow models overestimate the pressure drop, whereas those models based on the separated flow model often present underestimations. The models reported for wet gas are also incapable of predicting the pressure drop in this region with acceptable accuracy. Through an analysis of the prediction deviations, it is found that the Froude number of the liquid phase has a significant influence on the pressure drop of the wet gas, besides the Froude number of the gas phase. Then, three new correlations that are based on the homogeneous flow, Chisholm model, and Murdock model, respectively, were proposed based on the experimental result.     

外界压力消除铸件析出性气孔的测定

金属凝固时,由于气体的析出,会使铸件得到析出性气孔和增大缩孔体积（在此文中为简化叙述起见,把这两种由于析出性气体而引起的铸件内孔洞的增加统称为析出性气孔）。采用在凝固的铸件上施加压力的方法（如压力结晶、反压铸造,液压金属冲压等工艺）,可有效地消除铸件中的分散性显微孔洞。但外界压力除了可减少铸件中的因析出性气体而引起的孔洞外,还可同时减少铸件中因金属本身收缩所引起的缩孔,所以一直到现在,还没有设计出一种能单独地测定外界压力消除铸件中析出性气孔的效果的方法。本工作通过理论推导,提出一种能单独地测定外界应力消除析出性气孔效果的实验方法;还建议根据试验结果的数据,计算这种效果的参数方式;并利用了专门的装置,浇注了A1-1.5%Cu合金的试样,根据所指出的方法和参数公式,测得当铸件凝固时外界气体应力由0增至4公斤/厘米{sup}2时,可使因液体金属含氢量由0.187厘米{sup}3/100克增至0.365厘米{sup}3/100克时所引起的析出性气孔消除68%。     

差压法检测压力气体泄漏的研究

随着科学技术的发展,各种压力容器和设备的应用越来越广泛。相应地,压力气体的泄漏检测就显得尤为重要。在对比多种气体泄漏检测方法的优劣后,选择差压法来检测气体泄漏。对差压法泄漏检测的方法、原理、模型、检测回路、检测过程和气体泄漏量的计算进行了逐一的研究。