Numerical errors in discharge measurements using the KDP method

The kinetic differential pressure (KDP) method for measuring unsteady discharge in pressurized fluid conduits is introduced. The method utilizes two pressure measurements to estimate the unsteady discharge at the sampling rate of the pressure sensors. The technique is based on the linear approximation of the one-dimensional governing equations for transient flow. The application of the method is affected by two sources of error: the numerical error due to linear approximation of the one-dimensional governing equation and the modelling error representing the inability of the one-dimensional model to replicate the real transient behaviour. This research provides a first step in the verification of the KDP method by investigating the numerical error caused by the linear approximation. The numerical error is quantified as a function of the measurement location, system and signal characteristics. The method exhibits minor numerical errors if the system resonance is avoided.