This paper describes a model experiment of sootblower jets which have been used to remove fire side deposits of boiler tubes. A circular cylinder is used instead of a boiler tube. Flowfield around the circular cylinder placed in correctly expanded jets from a supersonic nozzle with a design Mach number of 2.0 and 2.4 is studied. Visualization by schlieren method and measurement of pressure on a cylinder are performed to diagnose the flowfield. The pressure coefficient on the cylinder is found smaller than that obtained by potential flow theory around a cylinder, especially, when the cylinder is located in the potential core region of the jets. The velocity distribution on the cylinder strongly depends on the flow Mach number just downstream of the shock wave generated in front of the cylinder.
