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首页> 外文期刊>International Journal of Heat and Fluid Flow >A LES investigation of off-design performance of a centrifugal pump with variable-geometry diffuser
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A LES investigation of off-design performance of a centrifugal pump with variable-geometry diffuser

机译：LES的几何可变扩散器离心泵超设计性能研究

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摘要

The effect of the orientation of the diffuser blades on the performance and detailed flow-physics through a centrifugal pump is investigated at design and an off-design conditions, with the latter corresponding to 40% of the nominal flow-rate. A Large Eddy Simulation (LES) approach was adopted, validated for both load conditions in earlier studies. It is shown that an adjustment of the diffuser geometry at off-design produces a significant improvement of the pump efficiency, thanks to the lower incidence at the leading edge of the stator blades. For comparison, simulations were carried out also at design flow-rate with the same setting angles of the diffuser blades. At off-design separation on their suction side is substantially decreased, as well as back-flow phenomena at the impeller/diffuser interface. The flow through the stationary channels becomes more uniform, although separation is still experienced on their shroud side, caused by incorrect inflow from the impeller. Due to the smoother interaction between moving and stationary parts, turbulent kinetic energy undergoes a decrease of almost an order of magnitude. In contrast, results at nominal flow-rate show better performance with the original geometry. At both loads the impact of the setting angle of the diffuser blades on the flow through the impeller is actually limited to the pressure side of its blades, near their trailing edge. At the reduced flow-rate separation and back-flow phenomena at the shroud, rotor blades suction side and impeller inlet are still present and practically unaffected, being mainly caused by the pressure gradients through the impeller, rather than by impeller/diffuser interaction.
机译：在设计和非设计条件下研究了扩散叶片的方向对通过离心泵的性能和详细的流动物理特性的影响，后者相当于额定流量的40％。采用了大涡模拟（LES）方法，并在早期研究中针对两种载荷条件进行了验证。结果表明，由于在定子叶片前缘处的入射角较小，因此在非设计时调整扩散器的几何形状可以显着提高泵的效率。为了进行比较，在设计流量下以相同的扩散叶片叶片设定角进行了仿真。偏离设计时，其吸入侧的分离以及叶轮/扩散器接口处的回流现象将大大减少。通过固定通道的流量变得更加均匀，尽管由于叶轮的不正确流入而导致在其导流罩侧仍发生分离。由于运动部件和静止部件之间的相互作用更为顺畅，湍动能几乎减少了一个数量级。相反，在标称流速下的结果显示了与原始几何体相比更好的性能。在这两个负载下，扩散叶片的设定角度对流经叶轮的流量的影响实际上仅限于其叶片的后缘附近的压力侧。在护罩处的流速分离和回流现象减小的情况下，转子叶片的吸入侧和叶轮入口仍然存在并且实际上不受影响，这主要是由通过叶轮的压力梯度引起的，而不是由叶轮/扩散器的相互作用引起的。

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