基于COD在线软测量的曝气最优控制

在水质检测中,化学需氧量(COD)很难实现实时、精准、经济的测量,应用支持向量机(SVM)建立预测模型,再用信息粒化时序回归方法来预测COD的变化空间,并根据定时人工检测COD质量浓度调整偏差,可以实现COD实时在线软测量。曝气环节能耗较大,传统曝气方法中鼓风机恒频运行常常造成电能浪费,根据COD质量浓度间接调节鼓风机频率,实现曝气系统的闭环控制,并应用于污水处理厂实际生产,结果表明吨水电耗有效降低了40%～45%。

风力机叶片气热除冰效率影响因素分析

为分析风力机叶片气热除水效率的影响因素,基于气热法对风力机叶片除冰效果进行试验分析,重点考虑铺层结构的导热效率和鼓风机速度(或频率)对除冰效率的影响。首先对叶片构造和铺层结构进行介绍,通过对铺层结构厚度测量估算导热系数,根据冬季叶片覆冰位置,验证气热除冰时叶片导热分布合理性。之后通过改变鼓风机速度(或频率)进行现场叶片除冰试验。试验结果揭示了气热除冰系统在对风力机叶片除冰过程中出现的除冰不均衡现象的根本原因,表明在保证通风管出风口温度稳定的前提下,鼓风机速度(或频率)越高,叶片表面除冰均衡性越好,除冰效果越显著。此外,在使用更大鼓风机频率的同时增强叶片内部环流,合理设置叶片内部环流结构可有效提高除冰效率并减小除冰耗时。研究结果可为工程实践提供指导。

Influence of the Karman Vortex Street on the Broadband Noise Generated from a Multiblade Fan

In the prediction theory for the broadband noise generated from a multiblade fan, the vortices in the Karman vortex street was divided into n pieces. The frequency distribution of the noise was estimated so that the Strouhal number could become constant even if the wake is spread by the diffusion. From the results of the measurement of the internal flow of the fan, it was found that the noise was related to the wake characteristics of the specific location in the scroll casing where the relative flow velocity was high. The noise operating in the vicinity of the maximum efficiency point of the fan was distributed over the domain from 500 Hz to 1250 Hz. It was experimentally proved that the influence of the Karman vortex street on the noise in the domains of high and low frequencies did not exist when the distribution of the estimated sound pressure level corresponded to the measured broadband noise.