The results of experiments on the thermal effect for tubes of different tapers are presented, and the effects of the tapering of the tube on the internal flow are shown. The results are summarized as follows: (1) With a tapered tube a higher temperature is obtained with smaller intervals of nozzle-tube spacings compared with the cylindrical tube. (2) With a tapered tube a higher frequency of flow oscillations and a shorter penetration length of contact surfaces which are considered to cause a higher temperature in the tube, together with stronger shock, are obtained (3) The velocity history at the open end is different for tubes with different tapers. When the taper is small, the amplitude of the velocity change becomes very small. (4) The pressure amplitude at the closed end becomes large for tubes with large tapers.