Automatic Followers of Velocity Head and Yaw Angle in Cascade Test

Abstract

In order to perform the automatic cascade test, the velocity head and yaw angle must be known by the automatic follower. The velocity head follower was based on the on-off positional control system with the detector which followed the height of the meniscus of the water manometer. The detector of the velocity head follower was consisted of one light source and two CdS cells and faced each other across the glass tube of the manometer. If both cells were lit through the water part, then the detector was moved upward along the glass tube until one of them was lit through the air part. Similarly, both cells were lit through the air part, then the detector was moved downward until one of them was lit through the water part. The detector of the yaw angle follower also had the same elements. However, it was not moved by the height of the meniscus, but the arrow head type yaw meter was rotated by motor on-off controlled until the differential pressure became zero in the U tube differential manometer. These data (the velocity head and the yaw angle quantities) were transformed to the electrical signals and then substituted to the automatic computer whose output were shown numerically the energy loss coefficient. In our first report the automatic follower were described and in the second the automatic computer will be treated. The features of the follower was followed; (1) Accuracy of velocity head about 1% at 20-60m/sec, (2) Error of yaw angle about 10min, at 40m/sec, (3) Following speed of detector 0.7mm/sec.