摘要
推导了射流泵理论模型方程中计算参数与断面几何和流动参数的关系,利用数值模拟结果,确定了理论模型中的计算参数,分析了理论计算参数随流量比的变化规律.结果表明:反力分布系数c1与吸入面积比c在最优工况近似相等,而随着流量比偏离最优工况,两者偏差增大;利用c值代替c1值不会导致理论计算结果显著误差;工作流体速度一定条件下,动量修正系数k1不随流量比变化而变化,近似为常数;k2随流量比变化呈双曲线形状,随着流量比增大,逐渐趋近于1;喷嘴流速系数1、吸入管路流速系数4为常数;扩散管入口断面流速分布均匀性对扩散管流速系数3值有重要影响;喉管流速系数2及喉管入口收缩段流速系数5随流量比增加而线性减少,是影响理论计算结果的主要参数.理论计算结果与试验结果吻合较好,验证了计算参数确定方法的可行性和理论模型的可靠性.
The relations of dimensionless coefficients, geometry parameters of cross-section and ffow variables have been derived in a theoretical model of jet pumps. Those coefficients were determined by using numerical simulation of flow in the pump, and then their relationships with flow ratio were ana- lyzed. It was indicted that the reaction force distribution coefficient cI is nearly equal to the suction area ratio c at the best efficiency point; at the other flow conditions, however, two coefficients show signifi- cant difference. In fact, replacing cj with c doesn＇t cause a remarked error in theoretical prediction re- sults. When the working fluid velocity keeps to be constant, the momentum correction coefficient kt is independent of flow ratio, thus can be treated as a constant; the coefficient k2 shows a hyperbolic func- tion against flow ratio, and asymptotically approaches to 1 as the flow ratio increases. The nozzle dis- charge coefficient Ф1 and suction chamber discharge coefficient Ф4 are constant in all the working con- ditions. The uniformity of velocity distribution in the diffuser inlet has a great influence on the diffuser velocity coefficient Ф3. The velocity correction coefficient at the throat Ф2 and the velocity correctioncoefficient Ф5 at the inlet to the nozzle of suction chamber decrease linearly as the flow ratio increases. They affect the results of theoretical model remarkably. The theoretical predictions show good agree- ment with the experiment results, confirming that the method proposed for determining the dimension- less coefficients is feasible and the model is reliable.
出处
《排灌机械工程学报》
EI
北大核心
2013年第1期1-6,共6页
Journal of Drainage and Irrigation Machinery Engineering
基金
国家自然科学基金资助项目(51176088)
中国博士后科学基金面上资助项目(2011M500315)
水利部公益性行业科研专项经费资助项目(201201085)
关键词
射流泵
计算参数
理论模型
动量修正系数
流速系数
jet pump
calculation parameters
theory model
momentum modification coefficient
velocity coefficient
