BPX型排水泵内流分析及降噪方案

Internal flow field analysis and noise reduction means of BPX drain pump

为了研究泵内流动诱导噪声源分布规律,从内部流动角度,运用计算流体动力学方法对一台典型的BPX型排水泵的内流场进行了数值计算,得到了在不同工况下泵内的速度、压力及涡量场分布特征.计算结果表明:泵过滤室内液流呈低速缓流状,异物过滤装置后盖板附近有环状非对称切向旋涡产生;过流通道面积突变使得叶轮吸入口入流条件较差;出液管内部流动出现明显的流动分离,由贯通流和低速回流区域组成;叶轮流道内部,特别是在叶轮轮毂周边及流道内靠近叶片背面附近,涡量分布密集,在叶尖附近也存在较强的涡量分布,出液管内有涡条带形成.同时,对模型泵进行了空气噪声测试,根据测试结果将泵运行过程划分为启动初期、正常运转期和空排期3个阶段,分析了各阶段的噪声特性,并提出了3种具有代表性的降噪方案,认为开设回流孔方案可行性较大.

In order to research the distribution law of noise sources induced by flow in pumps,the internal flow field in a typical BPX drain pump was simulated by computational fluid dynamics,and the distribution features of velocity,pressure and vorticity field at different running conditions were obtained.The computational results show that there is a low velocity fluid flow in the filter chamber.An unsymmetrical tangential vortex is observed around the back of the filter.Pump impeller inflow condition goes to worse due to sudden change of the flow passage section area before fluid flowing into the impeller.Flow in the outlet pipe separates,and consists of throughout and backflow with low velocity.Vorticity is concentrated in the impeller flow passage,especially around the hub,suction side of the impeller and impeller tips.A vorticity band also appears in the outlet pipe.Meanwhile,pump airborne nosie was also tested.Pump running process was divided into three steps,including startup,running and empty pumping.Noise features of three steps were obtained.Three typical noise reduction means were provided.It is considered that the means of adding backflow hole is more feasible.