Method and apparatus for open flow area classification

A classification gauge for measuring open flow area of a vane assembly including a leading vane, a following vane and opposite end buttresses, the open flow area being defined by a trailing edge of the leading vane, a convex portion of an airfoil surface of the following vane opposite the trailing edge of the leading vane and the inside surfaces of the opposite end buttresses, comprising

• a frame,
• datum means for accurate positioning the frame on the vane assembly,
• first and second sets of probes for respectively contacting the trailing edge of the leading vane and the airfoil surface of the following vane, one of the sets of probes being interconnected with a fixed portion of the frame, the other set of probes being interconnected with a first indicating link,
• first and second lateral probes for engaging the inside surfaces of the respective buttresses at opposite ends of the open flow area, one of the lateral probes being fixed relative to the frame, the other being interconnected with a second indicating link,
• means for urging the first and second sets of probes into uniform engagement with the respective vanes and for urging the lateral probes into uniform engagement with the buttresses,
• proportional means arranged for interaction with both the first and second indicating links, and
• indicator means responsive to the proportional means for providing an indication of open flow area.

In a method for accurately measuring the open flow area of a vane assembly including a leading vane, a following vane and opposite end buttresses, the open flow area being defined by a trailing edge of the leading vane, a convex portion of an airfoil surface of the following vane opposite the trailing edge of the leading vane and the inside surfaces of the opposite end buttresses, the steps comprising

• accurately positioning a classification gauge in the vane assembly, the vane assembly being positioned relative to three perpendicular axes,
• urging first and second sets of probes of the classification gauge into engagement with the trailing edge of the leading vane and the airfoil surface of the following vane,
• urging first and second lateral probes of the classification gauge into engagement with the inside surfaces of the respective buttresses, and
• effectively interconnecting the first and second sets of probes and the first and second lateral probes with an indicator means through proportional means arranged for effective interaction with both the first and second sets of probes and the first and second lateral probes in order to directly produce an indication of open flow area in the indicator means.

In a method for accurately measuring open flow area of a vane assembly including a leading vane, a following vane and opposite end buttresses, the open flow area being defined by a trailing edge of the leading vane, a convex portion of an airfoil surface of the following vane opposite the trailing edge of the leading vane and the inside surfaces of the opposite end buttresses, the steps comprising

• accurately positioning the vane assembly relative to three perpendicular axes within a classification gauge for locating one lateral end and one longitudinal side of the open flow area of the vane assembly,
• urging a first probe means of the classification gauge into engagement with an opposite longitudinal side of the open flow area of the vane assembly,
• urging a second probe means of the classification gauge into engagement with an opposite lateral end of the open flow area for the vane assembly, and
• interconnecting both the first and second probe means with an indicator means through a proportional mechanism arranged for interaction with both the first and second probe means in order to directly produce an indication of open flow area on the indicator means.