Performance calculation and experimental study on a hydrostatic journal bearing for turbopumps
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摘要:
针对重复使用液体火箭发动机涡轮泵,设计了试验用流体静压轴承,利用不可压层流润滑雷诺方程的线性性质,对轴承液膜压力进行数值求解,计算分析了分别采用水和液氮作为润滑介质时,轴承的承载力和流量特性与偏心率和供给压力的关系;进行了轴承的节流孔流量特性和水润滑试验。结果表明:静压轴承短孔(非典型小孔)节流器的流量系数远超出常用的小孔节流器流量系数的参考范围;在相同的工况下,数值计算得到的水润滑和液氮润滑静压轴承的质量流量相差很小;高速水润滑试验中,主轴在轴承中浮起后的位置主要由供给压力决定,在0~30 000 r/min的转速范围内轴承没有明显的动压效应;数值计算和试验结果均表明静压轴承的质量流量与偏心率基本无关。水和液氮润滑静压轴承性能数值计算和水润滑试验结果为进一步的液氮低温润滑试验奠定了基础。
Abstract:An experimental hydrostatic journal bearing intended for the reusable liquid rocket engine turbopump was designed and investigated through numerical calculation and experiments. The Reynolds equation for incompressible laminar fluid was numerically solved based on its linear characteristic and the static performance (load capacity and mass flow rate) of the bearing lubricated with water and liquid nitrogen versus eccentricity ratio and supply pressure was calculated and analyzed. The flow characteristic of the bearing restrictor was studied through experiment and the bearing lubricated with water was also tested. The flow characteristic experiment of the restrictor shows that the flow coefficient of this non-typical restrictor is much larger than that of orifice restrictors. The numerical results show that the mass flow rates of the bearing lubricated with water and liquid nitrogen are very close to each other under the present research condition. The high-speed water lubrication experiment indicates that the equilibrium position of the shaft in the bearing is mainly determined by the supply pressure and the bearing shows no obvious hydrodynamic effect in the speed range of 0~30 000 r/min. Both numerical and experimental results show that the mass flow rate of the hydrostatic journal bearing is largely independent of the eccentricity ratio. The numerical results of the bearing lubricated with water and liquid nitrogen, together with the water lubrication experimental results provide a reference for further cryogenic lubrication experiments.
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表 1 轴承的主要参数
Table 1. Main parameters of bearing
参数 数值 轴承内径D/mm 20 轴承宽度B/mm 14 平均半径间隙h0/μm 35 节流孔直径do/mm 0.64 凹腔数目n 4 润滑介质 温度/K 密度/(kg·m-3) 黏度/(10-6Pa·s) 水 293 998.2 1 005 液氮 77 807.7 163 表 3 流量特性试验结果
Table 3. Results of flow characteristics test
测点 第1次试验 第2次试验 第3次试验 Δp/
MPaQm/
(kg·s-1)Δp/
MPaQm/
(kg·s-1)Δp/
MPaQm/
(kg·s-1)1 0.99 0.049 7 0.91 0.049 0 0.95 0.050 9 2 1.81 0.069 3 1.74 0.068 2 1.80 0.069 5 3 2.76 0.085 4 2.76 0.085 2 2.72 0.084 9 4 3.67 0.097 8 3.71 0.098 4 3.74 0.098 5 5 4.59 0.108 5 4.61 0.109 3 4.59 0.109 1 -
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