燃油汽心泵的数值模拟与试验

作为离心泵的一种演变泵型,燃油汽心泵在航空发动机中应用前景良好,叶轮区形成的汽心对泵的工作状态和性能影响较大。基于RNGκ-ε湍流模型对汽心泵内流场进行了非定常汽液两相数值模拟,研究了进口节流活门开度与出口负载对汽心区域的影响规律。为验证数值模拟结果的精度,利用汽心泵样机开展了基本特性试验。结果表明,汽心泵内燃油汽化发生于叶轮进口端;汽心区域随出口负载减小逐渐扩张。扩张至叶片区后,燃油全部从叶片压力面一侧流道进入蜗室;其他工况不变时汽心区随节流活门开度减小而迅速扩张,2mm开度时泵的效率最低可降至20%以下。数值模拟与样机试验误差基本在10%以内。

汽心对汽心泵供油特性的影响研究

为研究汽心对供油特性的影响,对径向直叶片汽心泵进行了汽液两相非定常数值模拟。汽心大小可随进口节流活门开度和出口负载等变化,根据流量脉动情况分析了汽心对供油特性的影响规律;模拟了供油量对负载压力阶变的动态响应,据此获得汽心对流量动态性能的影响规律。结果表明,汽心不会造成供油量的显著脉动;活门开度在4~8mm范围时,汽心可减缓阶变对流量稳态值的影响,但使流量调节时间延长;2mm活门开度工况下,汽心接近叶轮出口,出口压力阶变越大,汽心调节后供油量脉动幅度也相应增大。

汽心泵特性分析与计算方法

本文给出汽心泵压头特性、汽心变化、泵内水力损失、集流器内压力分布和径向力等主要特性的计算法和程序,可估算新泵初始设计的特性、亦可对现有泵的特性近似计算。

汽心泵特性研究

通过理论分析和试验,导出汽心泵稳定工作的基本方程和性能参数之间的函数关系;分析了当转速、压力、流量和负载系数变化时,汽心对泵特性所起的调节作用;提出决定相对汽心直径的特征参数p_2/n^2D_2~2;还讨论了汽心泵的极限工作状态和最大流量调节范围。

汽心泵特性分析与计算方法

本文给出汽心泵压头特性、汽心变化、泵内水力损失、集流器内压力分布和径向力等主要特性的计算方法和程序框图。该算法可用来估算新泵设计初始阶段的特性,亦可用来对现有泵的特性作近似验算。

进口节流面积对汽心泵流动特性的影响分析

目前业界对汽心泵的工作机理尚未有清晰的认识,对泵在不同工况下其内流场、外特性的变化特征也不尽明确,因此开展相关燃油汽心泵性能验证及试验研究工作,对燃油汽心泵的后续研发、推进先进燃油控制系统的发展工作至关重要。

径向直叶片燃油汽心泵汽心形态数值模拟

为获得燃油汽心泵内气态区域的形成过程及形态的变化规律,基于renormalization group(RNG)k-ε双方程湍流模型与Schnerr-Sauer空化相变模型,对径向直叶片燃油汽心泵进行了整体三维建模与气液两相定常数值模拟,分析转速、进口节流活门开度、出口压力等因素对燃油汽心泵内气态区域的影响.结果表明:一定转速范围内气态区域随转速增加而扩大;转速不变时出口压力增加会使气态区域范围减小;气态区域扩张至极限位置即叶轮直径外,燃油汽心泵进入不稳定工况.RNGk-ε双方程湍流模型和与SchnerrSauer空化相变模型适用于燃油汽心泵汽心形态的数值模拟.

Improving Suction Performance of Centrifugal Pumps by Using Jetting Device

Improving the suction performance of centrifugal pumps by using jetting device is presented. The theoretical analysis, experimental study and engineering implementation show that suction performance of centrifugal pump can be improved with jetting device and be used for delivering the liquid media requiring high suction performance, whereas the efficiency and head of the pump will decrease a little. The effect of feed-back jetting on suction performance is the most obvious at design point. The suitable rate of feed-back flow is 2%-5%.

Efficiency in Boiler Feed Pumps for Industrial Steam Generation

This paper presents some opportunities to improve feedwater system efficiency for industrial boilers, usually consisting of multistage centrifugal pumps driven by three-phase induction motors. There is abundant literature on the efficiency in steam boilers. However, few deal exclusively with feedwater systems. The total horsepower in boiler feed pumps and the corresponding energy consumption estimated for Brazilian industries are as follows： 110.5 MWE of motor driven power and a yearly electricity consumption of 442 GWh for a population of 7,800 steam boilers, approximately. It is estimated that there can be an efficiency improvement in feedwater systems for industrial boilers of 30% on average. To a large extent, these opportunities reside in older boilers that are very common in the Brazilian industrial sector. The most common causes for the low efficiency of feedwater systems are： the control loop of the feedwater, oversized boilers and excessive operational pressure set. Sometimes, the boiler feedwater system can present more than one problem simultaneously. Any kind of solution involves some speed regulation, new pump and number of pumps. Each problem generation facilities were selected in which common inefficiencies cases, the improvement in efficiency can get to 37%. form of intervention in boiler feed pumps, such as： impeller trim, may have more than one solution. Three distinct industrial steam are present. The suggested solutions were analyzed. In these three