Revival of water table experiments in fluid mechanics courses, part I

Abstract

In a classroom environment, after a comprehensive theoretical discussion of compressible flows, it is beneficial to conduct a visual experiment in which students can observe these flows and some of the features associated with them. Experimental study of compressible fluid dynamics is associated with high equipment costs; therefore, conducting an experiment is not feasible for some colleges. This article describes an experiment implemented at Manhattan College upper division and graduate fluid dynamics courses at a relatively low cost. In the experiment, a water table hydraulic analogy was used. Theoretical considerations of this analogy are explained in this article. An area–velocity relation was used to study the Mach number at the exit of a Laval nozzle. The theory and measurement came within 10% of each other, which is sufficient for a teaching demonstration. This exercise can be conducted in two class sessions: (1) discussing the theoretical considerations and (2) performing the experiment and analyzing data. The overall experience is a good way to help students understand some of the compressible flow features, and further promote their interest in fluid mechanics.