Hydraulic Domestic Heating by Throttling

In this work an experimental investigation was carried out in order to explore the possibility of realizing a domestic heating system by throttling hydraulic oil. Considering the continuous increasing price of diesel oil, this work gains unique importance. Generating heat directly by throttling is realized using a simple environment friendly system which does not require oil transportation and storage, and eliminates the need for chimneys and annual preventive maintenance, as it is the case with heating by utilizing oil burners, which is prevailing in Jordan. Experimental results show that it is possible to raise the room temperature up to 70?C during 15 minutes which is not a limit value. Experimental results show that temperature rate could be increased by selecting the appropriate pump power and by connecting a number of throttles in parallel.

EXPERIMENTAL STUDY OF EFFECTS OF OPERATING CONDITIONS ON THE FLOW CHARACTERISTICS OF WATER HYDRAULIC THROTTLE

Experimental investigations are made on the effects of operating conditionson the flow characteristics of throttle when tap water is used as the working media. The researchedthrottles include cone poppet valve, ball valve, disc valve and dumping orifice. Operating conditionincludes poppet lift, working media, back pressure, medium temperature, etc. Because the vapourouspressure of water is much higher than that of oil, cavitation is easier to occur in water hydraulicelements and systems, so the effects of operating conditions on the cavitation characteristics ofthrottle are also researched.

Numerical Simulation on a Throttle Governing System with Hydraulic Butterfly Valves in a Marine Environment

Hydraulic butterfly valves have been widely applied in marine engineering because of their large switching torque, low pressure loss and suitability for large and medium diameter pipelines. Due to control problems resulting from switching angular speeds of the hydraulic butterfly valve, a throttle-governing control mode has been widely adopted, and detailed analysis has been carried out worldwide on the structural principle concerning speed-regulation and the load torque on the shaft while opening or closing a hydraulic butterfly valve. However relevant reports have yet been published on the change law, the error and the influencing factors of the rotational angular velocity of the hydraulic butterfly valve while opening and closing. In this article, research was based on some common specifications of a hydraulic butterfly valve with a symmetrical valve flap existing in a marine environment. The throttle governing system supplied by the accumulator to achieve the switching of the hydraulic control valve was adopted, and the mathematical models of the system were established in the actual conditions while the numerical simulations took place. The simulation results and analysis show that the rotational angular velocity and the error of the hydraulic butterfly valve while switching is influenced greatly by the drainage amount of the accumulator, resulting in pressure loss in the pipeline, the temperature of hydraulic medium and the load of the hydraulic butterfly valve. The simulation results and analysis provide a theoretical basis for the choice of the total capacity of the accumulator and pipeline diameters in a throttle governing system with a hydraulic butterfly valve.It also determines the type and specification of the hydraulic butterfly valve and the design of motion parameters of the transported fluid.

Effect of cavitation bubble collapse on hydraulic oil temperature

Cavitation bubble collapse has a great influence on the temperature of hydraulic oil. Herein, cone-type throttle valve experiments are carried out to study the thermodynamic processes of cavitation. First, the processes of growth and collapse are analysed, and the relationships between the hydraulic oil temperature and bubble growth and collapse are deduced. The effect of temperature is then considered on the hydraulic oil viscosity and saturated vapour pressure. Additionally, an improved form of the Rayleigh–Plesset equation is developed. The effect of cavitation on the hydraulic oil temperature is experimentally studied and the effects of cavitation bubble collapse in the hydraulic system are summarised. Using the cone-type throttle valve as an example, a method to suppress cavitation is proposed.

非全周开口滑阀阀控数字液压缸动态特性分析

现有阀控数字液压缸中集成的滑阀通常采用全周开口,其流量增益大、阀芯所受液动力大,严重影响数字液压缸的起动和切换时的动态响应特性。针对6种典型非全周开口滑阀结构,计算了各阀芯节流槽过流面积,确定了在过流面积相同的情况下,一级(U、V、K形)和二级(UU、UV、UK形)节流槽的结构参数;比较了不同结构形式的非全周开口滑阀的数字液压缸在阶跃信号下的响应和阶跃负载扰动的响应。仿真及实验结果表明:相较其他阀口形式,节流槽采用K形及UK形结构时,数字液压缸在阶跃输入信号下的响应较好;而相较于UK形节流槽,阀芯采用K形节流槽时,滑阀控制的数字液压缸的负载刚度更好,速度冲击更小,但活塞无杆腔建立工作压力较慢;阀芯采用UK形节流槽时,滑阀控制的数字液压缸的在相同负载干扰下响应速度更快。

阀式蓄能器对换挡液压系统压力冲击的影响

依据某重型车辆换挡液压系统,创新设计了一种带有阻尼节流槽的阀式蓄能器,通过流场仿真,分析不同活塞位移下的压力云图,根据实际工况配置阻尼槽的节流面积。通过换挡液压系统动态仿真模型,分析阀式蓄能器不同结构参数对蓄能器运动部件动态性能的影响规律,并且获得结构参数对作动离合器液压缸压力变化的影响机理。研究表明:阀式蓄能器U+K形阀口表现出二级节流特征,能够实现节流面积由大到小的变化规律;阀式蓄能器相较结构参数相同的弹簧式蓄能器,可使液压缸入口压力冲击幅值降低41%;增加U形节流槽宽度,可降低离合器液压缸入口压力冲击幅值;增加U形节流槽长度,压力冲击幅值无明显变化;增加复位弹簧刚度,可降低液压缸入口压力冲击。

高集成度节流嘴流动特性研究

针对飞机液压控制系统用节流嘴尺寸较小,常规试验手段难以获得节流嘴内部流场的流动参数的情况,以航空煤油为工质,对两种构型的节流嘴进行了阻力-流量特性的数值仿真,并对模型进行了试验验证,获得了Ⅰ型节流嘴在流量为1.25 L/min和2.22 L/min,温度为80℃和20℃条件下的内部流场,以及Ⅱ型节流嘴在流量为0.37 L/min和0.56 L/min,温度为80℃和20℃条件下的内部流场。结果表明:航空煤油在直管内和安全滤网内流动时,压力基本不变,压降主要在节流孔和安全网滤孔处产生,且节流孔处的压降为安全网滤孔处压降的2倍以上;不同流量下的节流嘴通道流场分布相似,只是压力、速度、湍动能等流动参数的数值大小有差异;节流孔和滤孔处的湍动能较大,原因为该处的流体质点之间剧烈掺混,速度脉动大;保持航空煤油的温度和出口压力不变,航空煤油的流量越大,节流嘴出入口的压降越大;温度变化导致航空煤油的密度变化,相同质量流量下,温度越低,节流嘴出入口压降越小。研究结果可为飞机液压控制系统用节流嘴的设计提供理论指导。

先导式节流阀比例电磁铁参数设计及优化

保证丘陵山地拖拉机在起伏山地或土质较硬地块作业时的牵引力和耕深之间的最佳匹配状态是丘陵山地拖拉机悬挂系统设计的重要指标。比例电磁铁作为节流阀电—机转换的主要元件,其性能优劣对控制节流口开度、实现流量的比例调节具有重要意义。针对丘陵山地拖拉机悬挂系统作业需求和电液比例阀设计要求,设计一种用于悬挂液压系统姿态调整的先导式节流阀比例电磁铁,对其关键结构参数进行设计,建立比例电磁铁数学模型,通过Maxwell对阀组流量特性的影响进行仿真分析。同时利用遗传算法对隔磁导向套厚度、隔磁环角度、隔磁环宽度和定子铁心深度等参数进行匹配优化,通过Maxwell对优化前后的比例电磁铁进行有限元分析。仿真结果表明:优化后的比例电磁铁在1~3 mm时电磁力几乎与X轴平行,具有更好的位移—力特性。建立先导式节流阀数学模型,通过Simulink对其进行动态特性和静态特性仿真,验证所设计的比例电磁铁参数的合理性。

具有自适应节流阀的液压平衡阀设计及动态特性分析

为了提高液压平衡阀的控制精度,通过新增流量测试环节利用非线性阀口开口的方式来补偿流量产生的背压偏差,设计了一种具有自适应节流阀的液压平衡阀。改平衡阀能够根据不同工况条件适应负载变化的液压平衡阀遇到节流口流量变化时,同样会导致背压发生改变。使用仿真软件Simulink对其进行优化分析。研究结果表明,在0.17 s时达到平衡状态,新平衡阀获得较优动态响应。新平衡阀达到了更优动态响应,可以在更短时间内达到平衡状态,可满足实际要求。该研究有助于提高平衡阀的节能效果,为后续的参数优化奠定基础。

浅水受限区水下油气田开发方案

针对国内浅水油气资源开发环境影响及空间受限等问题,本文提出了国产浅水水下生产系统的总体设计方案。通过对浅水水下生产系统关键设备结构进行分析,提出了一种满足受限区海域开发要求的环境友好型设计思路。结果表明:通过系统和总体布置的设计,国产浅水水下生产系统与深水相比在单体重量、作业方式、维护检修方面更加经济。

造型线模板回转液压缸缓冲装置的优化改造

针对模板回转液压缸自带缓冲节流阀流量调节分辨率不足的问题,借鉴缸尾常用缓冲结构,进行缸头缓冲结构的理论计算,并增设可调节的单向节流阀和溢流阀。结合液压回路进行原理说明,可为类似缓冲结构的设计提供参考。

液驱风力发电机组转速线性化控制及优化研究

通过风速传感器实时监测风速,并传送到控制器中,结合定量泵转速状态计算风力发电机组模型对结果跟踪,实现精确调节变量马达转速效果。研究结果表明,无论稳速还是变速下,马达转速动态表现出来稳定的变化规律,整体在1500 r/min上下波动,表明测试的结果是准确的。稳速下,加入节流阀调节转速前后,马达转速输出波动从±5 r/min降为±2 r/min;变速下,加入节流阀调节转速前后,马达转速输出波动从±15 r/min降为±5 r/min,具有很高的控制稳定性。该研究对提高风电设备运行稳定性具有很好的理论意义,易于推广应用。

履带起重机液压缓冲装置设计及动态特性分析

考虑活塞和油缸之间的偏心误差与油液压缩特性,设计了一种履带起重机液压缓冲装置,深入分析了液压缓冲装置的综合性能与缓冲力变化特征。构建得到缓冲装置动态冲击模型,对缓冲装置在瞬态冲击过程中的冲击特性开展了仿真测试。研究结果表明,缓冲行程时间为0.35s,回复行程时间为0.04s,实现了快速回程的过程。当冲击初速度提高后,缓冲力峰值与活塞运动位移显著增大,形成了更大包络面积,可以更高效吸收外部振动能量。该研究有效提高起重机节能效果,为后续的参数优化奠定了理论基础。

Cavitation Bubble Luminescence in Cone-Type Throttle Valve

In light of the light emission from cavitation bubbles under certain conditions, the phenomena of the cavitation bubble luminescence in the hydraulic cone-type throttle valve is focused in this paper. Firstly,the software of automatic dynamic incremental nonlinear analysis( ADINA) is applied to studying the flow field of the flow channel of the cone-type throttle valve. And the pressure distribution of the valve flow channel is obtained. The easyhappening area of cavitation in the cone-type throttle valve is also found out by ADINA. Then,the experimental research on the conetype throttle valve is carried out in this paper. The changing law of the hydraulic oil temperature in the corresponding region under different system pressure and the backpressure condition are experimentally researched. The relationship between the luminescence intensity and the cavitation intensity,the pressure,and the temperature are also studied. Finally,a summary of the causal relationship between the luminescence and cavitation in the cone-type throttle valve,the cavitation effect on the hydraulic oil temperature,and the method for the inhibition of cavitation bubble luminescence are presented. The results show that the light intensity increases with the increase of the cavitation intensity,and the luminescence can be inhibited by the increase of backpressure.

大吨位提升机箕斗过放液压缓冲系统冲击性能研究

针对箕斗易发生过放事故,提出了一种新型箕斗过放液压缓冲系统。分析了缓冲系统工作原理,建立了箕斗过放防撞缓冲系统数学模型,并基于AMESIM搭建了箕斗过放防撞缓冲系统仿真模型,首先对比验证了节流阀的缓冲效果,其次研究了箕斗冲击动能和系统关键参数对过放防撞缓冲特性的影响,研究结果表明:节流阀对液压缸压力波动有较好的缓冲作用,其通径大小对箕斗位移基本无影响;箕斗冲击动能增大,箕斗位移和缓冲时间增大;箕斗过放冲击动能主要由溢流阀消耗,溢流阀开启压力增大,缓冲时间减小,箕斗最大位移减小,改变溢流阀开启压力可有效控制箕斗位移;由8个吸能防撞单元组成的大吨位箕斗过放缓冲系统冲击小,箕斗降速平缓,对实际工况的大吨位提升机箕斗防撞装置设计具有理论指导意义。

自然循环下钠冷快堆中迷宫型节流件水力特性研究

迷宫型节流件常被安装在钠冷池式快堆主容器冷却系统、泵冷却系统等流动旁路中,使得进入这些旁路的流量达到设计值,来有效冷却设备,保证快堆的安全。目前国内对自然循环条件下节流件的阻力特性研究较少,本文对迷宫节流件在自然循环和强制循环两种条件下进行了实验和数值研究。首先,实验采用恒定温度(84℃)的液态水作为工质,得到了两种循环条件下节流件的阻力系数;其次,对节流件进行数值模拟,将不同湍流模型、壁面法向网格间距下的数值模拟结果与实验结果进行了比较,验证了数值模拟的有效性;最后,通过比较不同湍流模型的计算结果和流场细节,得出适合于两种条件下迷宫式节流件数值模拟的湍流模型,并发现回流漩涡是节流件的主要耗能方式,两种条件下模拟结果的差异主要集中在二次回流区域大小的不同,自然循环下回流区域明显大于强制循环,且收缩速度较慢。

多级多孔节流调节阀的声学特性研究

针对目前调节阀节流过程中振动与噪声较大等问题,采用多级节流和多孔节流相结合的方法设计多级多孔节流调节阀,并通过试验对多级多孔节流调节阀与典型球阀的水力特性和声学特性进行对比研究。结果表明,多级多孔节流调节阀的流量系数Kv和开度之间的变化规律接近线性;多级节流与多孔节流能够显著降低阀门的振动与噪声;多级多孔节流调节阀径向振动频谱图在35~40 Hz和115~120 Hz频带处不存在典型球阀径向振动频谱图中的峰值;多级多孔节流调节阀更适用于管道系统的流量调节,多级节流与多孔节流使得多级多孔节流调节阀的声学特性明显优于典型球阀。多孔节流与多级节流相结合的方法为阀门的减振降噪提供了新的思路。

基于AMESim的节流调速回路仿真与优化设计

本文以提高大负荷液压系统的负载能力为目标。首先,阐述了节流调速回路的基本结构与工作原理。其次,利用AMESim完成了节流调速回路的系统设计,并完成了节流调速回路的受力分析。最后,基于单神经网络PID算法,搭建了节流调速回路的优化模型,分析了执行元件在调速回路中对负载不同速度的作用规律。仿真结果表明,PID控制系统的引入增强节流调速回路的适用性,为设计速度控制回路提供了理论参考依据。

基于液压系统的风机叶片液压自调角系统

为确保冷却塔循环水系统安全可靠地运行,冷却塔风机转速以及叶片安装角度均按照最大换热量设定。但受生产工艺、环境温度等相关因素的影响,冷却塔风机的换热量在时刻变化,因此,冷却塔风机冷却能力与实际需求不匹配,造成大量能源浪费,为此,提出了一种基于液压系统的冷却塔风机叶片自调角的新型节能方法。首先,对自调角系统的工作原理进行了分析,利用Solidworks软件对自调角机构进行了结构设计,并对液压驱动系统工作原理进行了分析;然后,借助风力机气动载荷的计算方法,得到了液压系统提供的驱动力随安装角度变化的曲线;最后,利用AMESim仿真软件探究了多种液压回路自调角的工作特性,分析了调速阀内部元件节流阀开度对液压回路稳定性的影响。研究结果表明:自调角装置可以实现风机在不停机的工况下调节叶片的安装角度;采用PID调速阀液压回路可提高系统工作的精度和稳定性;当调速阀内部节流口的开度K=0.08时,可有效减少振荡时间,减小振荡峰值。

电液混合驱动大惯量回转系统特性与能效分析

为了解决大惯量回转系统频繁启动和制动作业导致节流损失大和制动动能浪费严重的问题,提出一种电气和液压混合驱动大惯量回转系统。系统采用永磁同步电机作为主动力源,控制回转系统运动;由蓄能器提供动力的液压马达作为辅助动力源,为电机启动加速提供扭矩补偿,蓄能器高效回收制动动能再利用。建立多学科联合仿真系统模型,基于主辅动力源合理供给原则,设计全周期工况识别速度控制策略,搭建电液混合驱动回转试验平台,对回转系统的特性和能效进行分析。研究结果表明,电液混合驱动大惯量回转系统,随着转速和转动惯量的变化,回转制动动能回收效率为40.5%~65.9%。相同工况下,与纯电机驱动系统相比,电液混合驱动系统启动加速时间减小1.2 s,制动动能回收效率为63.5%,降低系统能耗40.8%,使回转系统更加平稳地运行。