ASA 126th Meeting Denver 1993 October 4-8

3aPA8. Similitude in thermoacoustics.

Jeffrey R. Olson Gregory W. Swift

Condensed Matter and Thermal Physics Group, Los Alamos Natl. Lab., Los Alamos, NM 87545

The principle of similitude has been applied to thermoacoustics. Using similitude reduces the number of variables necessary to describe an experiment, which can greatly reduce experimentation time. In addition, it provides insight into the building of models with identical performance characteristics. Such models would duplicate even unanticipated nonlinear behavior. This allows one to build test prototypes that operate at conditions which are more easily accessible than the desired final product. For example, a prototype that operates at modest pressures using heavy gas such as argon could model equipment that is intended to operate at high pressure using light gas such as helium. Similitude has been verified using a large thermoacoustic engine operating with helium, neon, and argon, and has been found to be obeyed almost perfectly, even for nonlinear effects whose origin is not understood. Therefore it is believed this principle can be applied to make meaningful predictions using simpler, cheaper test models.