Improvement mechanism of wedged column on the cooling performance of vertical delta radiator

•A new type radiator with wedge-shaped gap has been proposed.•A 3D numerical model for dry cooling tower with delta radiator was set and validated.•The improvement mechanism of wedge on the delta radiator performance was clarified.•The cooling performance of delta radiators with wedge columns are better than usual.•A comprehensive index representing the effects of crosswind frequencies is proposed.