Numerical simulation of a Savonius turbine above an infinite-width forward facing step

The Savonius turbine, although simple in construction, typically has a maximum power coefficient (cP) of about 0.2. This is significantly lower than the cP of the axial flow propeller-type turbine which typically can be as high as 0.5. However, a simple means to improve the cP of a Savonius turbine is to install it above a forward facing step, for example, a cliff or a building. In this work, prior experimental results of the tow testing of a Savonius turbine installed above a finite-width bluff body were used to validate computational fluid dynamics simulation of the same experimental conditions. The validated simulation settings were then used to obtain the maximum cP of a similar turbine of finite width but installed above an infinite-width forward facing step over a range of installation positions above and behind the step

Towards simulation of NASA35 axial compressor

Purpose – This paper aims to validate and analyse the NASA35 axial compressor performance based on a numerical approach. Design/methodology/approach – Knowledge about flow property change during compressor operation at high and relatively low speed is still limited. This work provides a numerical approach to address these problems. Validation of numerical methods is proposed to generate confidence the numerical approach adopted, and after that, analysis of compressor performance at different operation conditions is carried out. Findings – The numerical methods proposed are proved capable in predicting compressor performance. Changes of flow property during compressor operation are discussed and explained. Research limitations/implications – The current numerical work is carried out based on the first stage of the NASA35 axial compressor, where the interactive effects from adjacent stage are not counted in. Furthermore, the steady-state simulation enforces an averaging of flow at rotor-stator interface, where the transient rotor-stator interaction is removed. Practical implications – This work validates the numerical methods used in the prediction of NASA35 axial compressor performance, and a similar numerical approach can be used for other turbomachinery simulation cases. Originality/value – This work reinforces the understanding of axial compressor operation and provides reliable results for further investigation of a similar type of compressor. In addition, details of flow field within the NASA35 compressor during operation are given and explained which experiments still have difficult to achieve