During the 3th International Workshop on Thermoacoustics held on October 26-27 at the Twente University in the Netherlands, Aster had presented some results of ongoing work on bi-directional turbines and the interface to thermoacoustic engines.

Since introduction on the Aster website by the end of 2012, and more recently as presented at the 2014 Pamir Conference, held in Riga,  the thermoacoustic community has recognized the concept of bi-directional turbines as an alternative for linear alternators in particular when power levels goes up. Experimental results are encouraging and had proven that

• bi-directional turbines can be scaled up in power unlimited
• efficiency raise with gas density.

In addition, emplacement of multiple stages in series is found to be a way to match the turbine circumferential speed to the available acoustic gas velocity and generator parameters.

Based on these results a design procedure is in progress allowing to characterize, scale and match bi-directional turbines to any type of thermoacoustic heat engine.

Some details may be found in the presentation

Beyond acoustic to electric conversion limits (Keynote)