Hot sounds could power long-lasting, reliable spacecraft engines

The extreme temperature differences in space could one day power long-lasting, reliable spacecraft engines, after researchers demonstrated a potentially crucial relationship between heat and sound.

The team from Purdue University and the University of Notre Dame in Indiana developed a theoretical model showing that thermo-acoustics can occur in solid materials. 

The phenomenon is more commonly studied in gas or liquids. Applying heat to a fluid in a duct or cavity causes the spontaneous generation of sound waves, vibrations that can be converted into other useful forms of energy. 

Fluids, however, are liable to leak, so the researchers considered using solids for a so-called thermo-acoustic machine to exploit temperature differences between hot and cold. 

“Although still in its infancy, this technology could be particularly effective in harsh environments such as outer space, where strong temperature variations are freely available and when system failures would endanger the overall mission,” said mechanical engineer Fabio Semperlotti. 

With the blazing Sun on one side and deep space on the other, temperature changes could cause vibrations that could be converted into electrical energy for spacecraft power. Solid materials’ resistance to leaks could create long-lasting machines, the team added. 

The researchers will now test their calculations and modelling of a thermo-acoustic metal rod in real-life experiments.

The findings were presented at the 175th meeting of the Acoustical Society of America.