Effects of different cylinder roof structures on the vortex of cyclone separators

•Compared with the Q criterion, the Ω-method can more accurately obtain the vortex structure inside the cyclone separator.•Improving the cylinder roof structure of the cyclone separator can make the vortex of the cyclone separator better, which is beneficial to suppressing the top ash ring and short-circuit flow.•The arc-shaped cylinder roof and the wedge-shaped cylinder roof can improve the flow field distribution of the cyclone separator, balance the vortex structure, and significantly improve the separation performance.