Measurement of small normal velocity components in subsonic flows byuse of a static pipe

Abstract

A concept for measuring small normal velocity components in subsonic flows by use of a static pipe has been developed and tested. A theory is presented which allows one to relate measurements of the difference of static pressures across a static pipe in a slightly disturbed flow to the axial derivative of the velocity component normal to the pipe. This derivative may be integrated, after fixing the constant of integration, to give the normal velocity component distribution along the pipe. The theory is restricted to small normal velocity components relative to the main freestream flow which is aligned with the pipe axis. The theoretical development presented here is primarily concerned with two-dimensional disturbance fields, but results are given for three-dimensional disturbance fields also. An experimental application of the concept to measure the disturbance fields arising in a two-dimensional wind tunnel is described. These experiments show how the present static-pipe concept can be used in a practical experimental situation.