﻿ 冲压空气涡轮泵的温控节流孔计算方法<sup>*</sup>
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1. 北京航空航天大学 交通科学与工程学院, 北京 100083;
2. 航空工业金城南京机电液压工程研究中心, 南京 211106

A calculation method for temperature control orifice of ram air turbine pump
WANG Yan1, YIN Yafeng1, CHEN Jinhua2, JIANG Pei2
1. School of Transportation Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100083, China;
2. AVIC Jincheng Nanjing Engineering Institute of Aircraft System, Nanjing 211106, China
Received: 2016-06-23; Accepted: 2016-10-01; Published online: 2016-11-16 15:38
Foundation item: National Natural Science Foundation of China (51375029)
Corresponding author. WANG Yan, E-mail: wybuaa@buaa.edu.cn
Abstract: Ram air turbine (RAT) pump, by transforming the mechanical energy into hydraulic energy, can be used to control the aircraft rudder in emergency situation. Its performance of rapid response is critical to ensure the aircraft's safety. Exposed to low-temperature atmosphere for long time, the high viscosity of hydraulic oil will hinder the rapid start of the hydraulic pump, and an effective method for this problem is to introduce the high-pressure oil into aircraft RAT pump from the main hydraulic system. Taking RAT pump as research object, this paper explores the calculation method of minimum temperature control orifice for the RAT pump. First, it explains the thermal insulation theory of the RAT pump which is equipped with temperature control orifice in standby mode and proposes an algorithm of the orifice. Second, it establishes RAT pump's thermodynamic model and deduces the calculation formula of the orifice's diameter. Next, it establishes temperature control system's thermodynamic model with MATLAB and calculates the results. Finally, it verifies the correctness of the algorithm through simulation calculation, and energy saving effect is remarkable.
Key words: ram air turbine (RAT)     aviation hydraulic pump     thermal insulation     thermodynamics     orifice

RAT泵是恒压变量柱塞泵，其热力学建模是确定节流孔的关键。有关液压泵和液压系统的热力学建模，国内外学者进行了相关研究。

1 RAT泵保温原理

RAT泵保温原理如图 1所示。图中：q0为通过温控节流孔的油液体积流量；P0T0分别为温控节流孔前的油液压强和温度；P1为管道内和泵内高压区的油液压强；T1为温控节流孔后连接管道内油液温度；P2为泵内低压区的油液压强；T2为RAT泵内油液平均温度；q1为单个柱塞副泄漏体积流量；q2为单个滑靴副泄漏体积流量；q3为配油盘副泄漏体积流量[19]Tout为壳体外部的环境温度。

 图 1 RAT泵保温原理 Fig. 1 Thermal insulation theory of RAT pump

RAT泵系统的生热功率和散热功率共同决定了RAT泵内油液温度。RAT泵生热主要包括：① 油液经过温控节流孔时的压降生热；② 管道内油液强制对流换热；③ 油液经过各摩擦副缝隙泄漏生热；④ 泵体内油液强制对流换热。RAT泵散热功率主要包括：① 管道壳体与外界空气的对流换热；② 管道壳体与外界的辐射换热；③ 泵壳体与外界空气的对流换热；④ 泵壳体与外界的辐射换热。辐射换热与对流换热相比，影响较小，因此在计算时忽略不计。

 图 2 温控节流孔计算方法 Fig. 2 Calculation method of temperature control orifice
2 RAT泵热力学建模及温控节流孔计算

2.1 系统生热功率

1) 管道生热功率

 (1)

 (2)

2) RAT泵体生热功率

 (3)

 (4)

 (5)

 (6)

 图 3 柱塞副和滑靴副 Fig. 3 Plunger pair and slipper pair
 (7)

 图 4 配油盘副 Fig. 4 Oil-distributing pair
2.2 系统壳体散热功率(忽略辐射换热)

1) 管道散热功率

 (8)

2) RAT泵壳体散热功率

 (9)

2.3 液压油密温特性

 (10)

2.4 液压油黏温特性

 (11)

2.5 温控节流孔计算方法

1) RAT系统热平衡方程组

 (12)

2区内RAT泵体部分热平衡方程：

 (13)

2) 流量守恒方程

 (14)

 (15)

3) 温控节流孔直径计算公式

 (16)

3 RAT泵仿真

 参数 参数设定 温控节流孔前油液压强P0/MPa 28 壳体油液压强P2/MPa 0.5 温控节流孔温度T0/℃ 60 壳体保温温度T2/℃ 55 机舱环境温度Tout 飞行高度H的函数 油液热容c/(J·(kg·℃)-1) 1 967.35 对流换热系数α 飞行高度H和舱内风速V的函数

3.1 最佳温控节流孔计算

 图 5 不同工况下的温控节流孔直径理论值 Fig. 5 Theoretical diameters of temperature control orifice under different working conditions

di中最大值[di ]max=0.313 mm作为最佳温控节流孔直径do，所在工况点为H=5 000 m，V=10 m/s，此处空气密度为0.756 kg/m3，环境温度为-17.5℃。

3.2 温控节流孔温度校核

 图 6 加入温控节流孔前后的泵体稳定温度对比 Fig. 6 Comparison of equilibrium temperature of pump body before and after assembling temperature control orifice

3.3 能耗对比

 图 7 加入温控节流孔前后系统稳定流量对比 Fig. 7 Comparison of balanced flow of system before and after assembling temperature control orifice

4 结论

1) 提出的温控节流孔计算方法经过仿真验算满足RAT泵的全工况保温要求；同时，可大幅度降低保温能耗，节能效果显著。

2) 对流换热系数对RAT泵的散逸热能有较大影响，提高对流换热系数的准确性有助于提高温控节流孔的计算精度。

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#### 文章信息

WANG Yan, YIN Yafeng, CHEN Jinhua, JIANG Pei

A calculation method for temperature control orifice of ram air turbine pump

Journal of Beijing University of Aeronautics and Astronsutics, 2017, 43(7): 1287-1292
http://dx.doi.org/10.13700/j.bh.1001-5965.2016.0545