For improving the reliability of rotating machinery, it is extremely important to predict fluid force acting during the machine operation. Recently, CFD (Computational Fluid Dynamics) analysis technology has been applied to the evaluation of fluid forces. In order to verify CFD analysis and improve its accuracy, visualization and measurement technology of fluid forces are a useful tool. Regarding the verification technology, Mitsubishi Heavy Industries, Ltd. (MHI) has been working on the visualization of unsteady fluid forces using pressure sensitive paint (PSP). In this study, we improved this technology to enable measurement in narrow sections, and applied it to a seal of rotating machinery and compared the results with those of CFD analysis. As a result of the measurement, we were able to obtain a detailed pressure distribution, which led to a better understanding of the mechanism of fluid force generation. In addition, we verified the difference between the measurement using PSP and the CFD analysis, which led to the improvement of evaluation methods for the future.
