Jet pumps for thermoacoustic applications: design guidelines based on a numerical parameter study

TL;DR

This study uses numerical simulations to analyze jet pump geometries for thermoacoustic applications, providing design guidelines by identifying optimal parameters and limitations of existing theories.

Contribution

It offers a comprehensive numerical parameter study of jet pump geometries, establishing new design guidelines and clarifying the applicability of quasi-steady theory.

Findings

Four flow regimes identified in jet pump performance

Optimal operation region defined based on scaling parameters

Quasi-steady theory limited to small operation regions

Abstract

The oscillatory flow through tapered cylindrical tube sections (jet pumps) is characterized by a numerical parameter study. The shape of a jet pump results in asymmetric hydrodynamic end effects which cause a time-averaged pressure drop to occur under oscillatory flow conditions. Hence, jet pumps are used as streaming suppressors in closed-loop thermoacoustic devices. A two-dimensional axisymmetric computational fluid dynamics model is used to calculate the performance of a large number of conical jet pump geometries in terms of time-averaged pressure drop and acoustic power dissipation. The investigated geometrical parameters include the jet pump length, taper angle, waist diameter and waist curvature. In correspondence with previous work, four flow regimes are observed which characterize the jet pump performance and dimensionless parameters are introduced to scale the performance of the various jet pump geometries. The simulation results are compared to an existing quasi-steady theory and it is shown that this theory is only applicable in a small operation region. Based on the scaling parameters, an optimum operation region is defined and design guidelines are proposed which can be directly used for future jet pump design.