The calibration problem

When measuring gas pressure changes in a container, for example an engine cylinder or a gun, by means of a piezoelectric pressure transducer, highly relatively accurate values must be made available in order to obtain the specified absolute accuracy. For this, special measuring and calibrating techniques are necessary, which allow the quantitative determination of the dynamic measuring properties of the transducer. The output from the transducer is in electric voltage. Therefore we must perform the calibration of the transducer so as to finally get the pressure. This is not difficult when we are working with a static pressure. The design of the equipment which enables well defined dynamic pressure measurement is much more complicated. This problem was solved by different authors by using a hydraulic pressure chamber, see [3]. For such a system we developed in our recent research project an experimental method for the dynamic pressure calibration. The essential problem connected with this method consists in the development of a physical model which allows a mathematical description of the hydraulic pressure pulses. This model enables us to calibrate a dynamic pulse pressure transducer in absolute pressure units. The schema of the experimental method is given in Figure 13.1. In the next chapter we will define a physical model using the results contained in [1].