Experimental Investigation of Instabilizing Mechanism of Super High Pressure Pump Induced by Noncontacting Seal

在泵的设计中，为了防止高压泵的泄漏流动，减小了非接触式密封的间隙，但减小间隙会引起不稳定的振动。本文分析了非接触密封产生的流体力及其对转子振动的影响。首先，建立了测量非接触密封产生的流体力的实验装置，通过测量轴向和周向的流量分量，分析了流体力的失稳机理。即通过改变转子的旋转速度和转速，测量了密封内的流量分布和压力分布，并由测量得到的流体力，从理论上得到了密封中间隙流动引起的失稳力，建立了与实验结果定性一致的密封设计数学模型。通过以上分析得出：(1)流体力随涡动幅度的增大而增大，随密封间隙的增大而减小。(2)进气涡流速度对转子系统的稳定性影响很大。正的涡流速度对转子是不稳定的，负的涡流速度是稳定的。(3)切向流体力随着转轴转速的增加而增大，对转子系统产生不稳定影响。(4)轴向速度对转子系统的稳定影响。此效果表示为径向的流体力。(5)与质量和阻尼项的系数相比，刚度项系数K_&lt；xx&gt；，K_&lt；xy&gt；对进气涡流速度的影响较大。(6)实验结果与无限宽近似理论得到的理论结果在定性上是一致的，但在数量上存在差异。

In the pump design, clearance of noncontacting seal is decreased in order to prevent the leakage flow in a high presure pump, but unstable vibration may occure by decreasing the clearance. In this study fluid force induced by the noncontacting seal and also the vibration of rotor induced by it's fluid force are analyzed.First an experimental apparatus to measure the fluid force induced by the noncontacting seal is built and instability mechanism of the fluid force are analyzed by measuring the axial and circunferencial flow components. That is, flow distribution and pressure distribution in the seal are measured for changing whirling speed and spinning speed of the rotor and the fluid force is obtained from the above measured values.Next the instability force induced by the clearance flow in the seal is theoretically obtained and nathematical model for design of seal is formulated, which is qualitatively coincident with the experimental results.It is concluded from the above analysis; (1) Fluid force increases as the whirl amplitude increases, but it decreases as the seal clearance increases. (2) Inlet swirl velocity effects very much on the stability of rotor system. Positive swirl velocity acts unstable to the rotor and negative one does stable. (3) Tangential fluid force increases as the spinning speed of the shaft increases and it effects unstable to the rotor system. (4) Axial flow velocity effect stable to the rotor system. This effect is represented as the fluid force of the radial direction. (5) Coeffecients of stiffness term K_<xx>,K_<xy> are effected much for the inlet swirl velocity compared with coeffecients of mass and damping terms. (6) The experimental results and the theoretical results obtained by infinite width approximation theory coincide qualitatively but these results have discrepancies in quantity.