Abstract
Heat transfer has been investigated on the end surface of cylinder enhanced by an annular jet from a channel installed in the displacer. The heat flux was estimated from heat generation in the foil heaters each temperature of which was controlled with CTA circuit individually. The heat flux histories for higher reciprocating speeds showed slow-changing waveform. So, the response of the temperature controlling system has been investigated in the present study. The frequency response of CTA circuits was measured, and transfer function from heat generation in the foil heater to its temperature was derived assuming one-dimensional heat conduction in the base plate of the foil heater. The sensitivity from actual heat flux to the working gas to its estimation was calculated, which showed cut-off frequency about 52 Hz. This is not sufficient for the measurement but it can be improved by dumping high frequency as to suppress undesirable oscillation and making high gain and small integration time of the controller to make the gain higher around several hundreds hertz.
