Self-excited oscillation of thermoacoustic engine is a very important characteristic, can start up, start up the ease of all directly affect the use of heat engines.
To learn in a small high frequency of the thermoacoustic engine vibration parameters in the process of system changes, this study chooses the resonance tube diameter of 20 mm, regenerator purpose from 200 stainless steel screen filler, working medium for helium, average working pressure of 2.
5 mp, regenerator by water cooling to keep the cold end heat exchanger in the environmental temperature.
Experiment, the heating power of hot end to the 120 w, as the change of time, energy gradually accumulated in the regenerator hot end, regenerator hot end temperature.
When temperature t rose to 610, when the temperature is a process of rising abruptly, in a short span of 3 s, it rose to 648.
6 k, temperature by began falling rapidly, and in more than ten seconds to achieve stability, temperature is 570 k only at this time.
As you can see, the regenerator hot end temperature and initial temperature of stable work is very big difference, for the purpose of this experiment of small thermoacoustic engine, the temperature difference is close to 80 k.
Also see, after the system is stable, the regenerator hot end temperature even than before vibration temperature is lower, the causes of this phenomenon is mainly produced by thermoacoustic effect, temperature in regenerator hot end has not yet reached the critical temperature, with the increase of temperature, the main in the form of heat conduction heat conduction from the regenerator hot end to the cold end heat exchanger, the temperature rise is relatively slow, when the system vibration, a large number of thermal instantaneous flow to the regenerator, heat accumulation in a flash in the regenerator hot end, resulting in the regenerator hot end temperature rise abruptly, as the system oscillation stability, heat into work, part of the side was taken away by the cold end cold water, and on the basis of the heat, compared with pure heat conduction, the gathered in the regenerator of heat will be reduced greatly, the temperature goes down, even working temperature stable vibration than the temperature of the former is lower.
This is a fairly complex thermal dynamic process, so far, has become an accurate model to describe.