Increasing of work flow on the thermoacoustic system by control of the temperature gradient within the stack

A gas column in a tube with a temperature-gradient spontaneously begins to oscillate when air turbulence occurs. The work flow produced in the stack, ΔI, is important for the thermoacoustic oscillation. The amount of ΔI is determined by the shape of temperature-gradient. Experimental studies on thermoacoustic systems are previously assessed by measurement of temperature ratio, TH/TC, of the stack; however, investigation for distribution of temperature within the stack is less discussed. In order to examine the influence of a temperature-gradient within the stack on the thermoacoustic oscillation, we propose that control method for the temperature-gradient under the same TH/TC. In particular, the control of the temperature distribution is implemented in actively changing the internal temperature by additional nichrome heater in middle of the stack. The sound pressure in the standing-wave thermoacoustic system is measured at several temperature distribution by the proposed method. Furthermore, ΔI was calculated based on the measured sound pressure. As a result, the work flow by the control of a temperature distribution have increased, and it was qualitatively estimated by the slope of heat flux within the stack from temperature distribution.