Unsteady shock interaction of moving bodies by means of Mach-Froude hydraulic analogy
Abstract
Unsteady motions of test articles in supersonic flows with shock-shock and shock-body interaction affect the kinematics and the subsequent trajectory of these test articles. The pressure changes downstream of each shock, causing streamwise surface pressure differences on test articles. For trajectory precision, it is vital that the pressure is symmetric. It is of vital requirement that the development of the unsteady shock patterns from multi-body problems is understood, both qualitatively and quantitatively observed through experiments. Analytical predictions based on quasi-steady assumptions sometimes fail to accurately compute trajectories. The problem here is how to obtain reliable quantitative or qualitative velocity field information, from a rotating observer position. An alternative is to employ the ubiquitous supersonic wind tunnel and perform the Galilean transformation of a stationary fluid with a moving test article to a stationary test article with moving fluid. The problem here is in not only the observation of the fluid dynamics, there will also be tunnel wall shock reflections, disturbing the experiment and the safety risk of performing the experiment in the first place. A water table facility is used to study unsteady compressible flow by means of a fluid dynamic analogy, where waves on a water surface behave identically to shock waves in two-dimensional supersonic flow. Because of the low flow speed of the water, test article motions, relative to the flow speed is low and is performed at nondimensionally high rates. The water waves are visualized with an optical shadowgraph system, identical to shockwaves in supersonic flow. The results are compared theory and computations.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 28, 2023
- Source ID
- W911NF2310270
Entities
People
- Kenneth Granlund
Organizations
- Army Contracting Command
- North Carolina State University
- United States Army