Effects of casing angle on the performance of parallel hub axial annular diffuser

In this paper, the effects of non-swirling and swirling flow on the performance of parallel hub axial annular diffuser has been investigated. The study was conducted on a fully developed swirling flow and non swirling flow to predict the separation of the flow from the wall. Three different annular diffusers were used with casing wall angles of 3 degrees, 6 degrees, and 9 degrees. Furthermore, various swirl angles (0-25 degrees) at the inlet of diffusers have been investigated to analyze the performance across the length. It was found that parallel hub axial annular diffuser performance increases up to a certain length as the inlet swirl angle increases. However, the performance also improves as the diffuser area ratio (AR) increases. The performance is evaluated based on the static pressure recovery coefficient (C-p) and the total pressure loss coefficient (C-TL). The highest possible pressure recovery is achieved by the 12 degrees swirl angle with a casing angle of 6 degrees.