CFD predictions of lobed mixer performance Original Research Article

A finite volume calculation procedure has been used to predict the flow and temperature mixing in a multilobed mixer/nozzle geometry. The method adopts a non-aligned mesh to solve the steady-state three-dimensional elliptic equations describing the flow within the lobes. The calculation of the downstream mixing duct is then coupled with the lobe flow predictions to allow for the prediction of the complete lobed mixer/nozzle system. The calculation method and some initial predictions have been presented in [1]. The basic model and an improved version of the method obtained by implementing a higher-order finite-difference scheme are employed in the present computations to assess numerical accuracy. A series of numerical parametric studies are then undertaken to investigate performance variations brought about by changes in mixer inflow conditions. Attention is focussed on the prediction of overall performance parameters such as mixing effectiveness and total pressure losses which are essential in engineering design studies. It is demonstrated that the CFD method used, is capable of providing accurate and useful information for design purposes, and flowfield/temperature distributions which are otherwise difficult and expensive to obtain. It forms an important new tool for the evaluation and optimisation of internal lobed mixer configurations.