Paper 3: Transient Heat Flow Investigations Using an on-Line Computer

Abstract

This paper describes some experiences using an on-line computer for transient heat flow investigations. It has been possible to link the experimental equipment to the core of a small high-speed digital computer by way of a multiplexer arrangement which enabled the output of several sensors attached to the experimental equipment to be monitored, sampled, and stored in the computer core at an exceptionally fast rate. It has been shown that, provided access can be had to such a computer installation, it is possible to accurately investigate the output of thermocouples which have a time constant of less than 0·25 μs. The sampling rate ensures that frequency components above 10 kc/s in the transient heat flow phenomena can be accounted for. The use of on-line data sampling, described in this paper, ensures that the laborious and time-consuming task of retrieving data from, say, film records or ultra-violet records, can be rejected as well as the effort of transferring such data to a medium suitable for input to a high-speed digital data-processing computer with the possibility of accompanying errors involved owing to manual handling of the data. The use of multi-channel inputs to the control computer set-up ensures that a maximum of 64 signals can be accommodated simultaneously (although only five are described), and with the sample rates resulting from the use of the on-line equipment, it provides a means of monitoring phenomena such as shock propagations, flame propagations, etc., which might otherwise have been impossible within the accuracy range desirable. A full description is given of the requirements of the auxiliary equipment necessary for the investigation of transient heat flow using the control computer.