Abstract: An object is to provide a catalyst which has high heat resistance and which can allow for production of methacrylic acid at a high yield and to provide methods for producing methacrylic acid and methacrylic acid ester with the catalyst, and the object is achieved by use of a catalyst having a specified peak in powder X-ray measurement.

Abstract: An object is to provide a catalyst which has high heat resistance and which can allow for production of methacrylic acid at a high yield, and to provide methods for producing methacrylic acid and methacrylic acid ester with the catalyst, and the object is achieved by use of a catalyst having a specified 31P-NMR spectrum.

Abstract: An air discharge device includes a duct that defines a flow passage through which a working air flow to be discharged passes, and a hole forming member defining an air discharge hole as an outlet of the working air flow. The hole forming member has a vortex generation structure configured to generate an auxiliary vortex having a vortex characteristic including a vortex rotation direction and a vortex axis direction. The vortex characteristic of the auxiliary vortex is different from that of a lateral vortex generated by the working air flow at a downstream side of the air discharge hole. The vortex generation structure is configured in the hole forming member so that the auxiliary vortex collides with the lateral vortex in a state where at least one of the vortex rotation direction and the vortex axial direction of the vortex characteristic is different from that of the lateral vortex.

Abstract: An air discharge device includes an air discharge unit for discharging an air flow. The air discharge unit includes at least one main hole from which an air flow is blown out as a working air flow, and a separation structure configured to separate a central portion of a thickness of a velocity boundary layer of the working air flow from a center line of the main hole at a downstream side of the main hole.

Abstract: An air discharge device is configured to discharge an air flow. The air discharge device includes a main hole for discharging an air flow as a working air flow, an auxiliary hole provided around the main hole to discharge a support air flow, and a vortex suppression structure configured to suppress development of vortices generated in a velocity boundary layer of the working air flow at a downstream side of an outlet of the main hole. This vortex suppression structure is configured to make a central portion of the thickness of the velocity boundary layer of the working air flow at the downstream side of the outlet of the main hole to be closer to a mainstream of the support air flow, at the downstream side of the outlet of the main hole.

Abstract: An air discharge device includes an air discharge unit for discharging an air flow. The air discharge unit includes at least one main hole from which an air flow is blown out as a working air flow, and a separation structure configured to separate a central portion of a thickness of a velocity boundary layer of the working air flow from a center line of the main hole at a downstream side of the main hole.

Abstract: An air discharge device is configured to discharge an air flow. The air discharge device includes a main hole for discharging an air flow as a working air flow, an auxiliary hole provided around the main hole to discharge a support air flow, and a vortex suppression structure configured to suppress development of vortices generated in a velocity boundary layer of the working air flow at a downstream side of an outlet of the main hole. This vortex suppression structure is configured to make a central portion of the thickness of the velocity boundary layer of the working air flow at the downstream side of the outlet of the main hole to be closer to a mainstream of the support air flow, at the downstream side of the outlet of the main hole.

Abstract: An air discharge device includes a duct that defines a flow passage through which a working air flow to be discharged passes, and a hole forming member defining an air discharge hole as an outlet of the working air flow. The hole forming member has a vortex generation structure configured to generate an auxiliary vortex having a vortex characteristic including a vortex rotation direction and a vortex axis direction. The vortex characteristic of the auxiliary vortex is different from that of a lateral vortex generated by the working air flow at a downstream side of the air discharge hole. The vortex generation structure is configured in the hole forming member so that the auxiliary vortex collides with the lateral vortex in a state where at least one of the vortex rotation direction and the vortex axial direction of the vortex characteristic is different from that of the lateral vortex.