Work flux density measurements in a pulse tube engine

A heat engine called a pulse tube engine has been recently proposed, which consists of only a few parts, namely, differentially heated stacked metal meshes in a cylinder and one piston, coupled to a flywheel. We built the prototype engine and tested its working mechanism from the standpoint of a thermoacoustic framework. We measured the work flux density distribution over the cross section of the pulse tube to elucidate the work source of the engine. This engine belongs to the standing wave engine group and the work source resides not in the stacked metal meshes but in the pulse tube.