Kumar Bimlesh, Rao Achanta Ramakrishna
Indian Institute of Science, Bangalore, India.
Environ Technol. 2009 Aug;30(9):947-51. doi: 10.1080/09593330902988737.
Shear rate in a surface aeration system exerts a profound effect on its performance, affecting the mixing pattern, the power requirement and oxygen transfer process. Based on theoretical analysis, it is shown that the shear rate gamma in the fluid is a function of the rotational speed N of the impeller in surface aeration systems. Analysis shows that the shear rate varies linearly with N in laminar flow and its behaviour is non-linear in a turbulent flow regime. Experimental correlations of gamma with N have been developed in the present study for different sized surface aerators. Scale-up or scale-down criteria for oxygen transfer rate have been developed, which relate oxygen transfer rate to shear rate in surface aeration systems.
表面曝气系统中的剪切速率对其性能有深远影响，会影响混合模式、功率需求和氧气传递过程。基于理论分析，结果表明流体中的剪切速率γ是表面曝气系统中叶轮转速N的函数。分析表明，在层流中剪切速率随N线性变化，而在湍流状态下其行为是非线性的。本研究针对不同尺寸的表面曝气器建立了γ与N的实验关联式。已制定了氧气传递速率的放大或缩小标准，该标准将表面曝气系统中的氧气传递速率与剪切速率联系起来。
