Improved accuracy, second-order response model for pressure sensing systems

The primary difficulty with obtaining high-fidelity pressure measurements is acoustical distortion within the various components of the pneumatic system. The method of Berg and Tijdeman is the de facto standard for the aerospace industry for calculating the frequency response of pressure-sensing systems. However, the model is complex, difficult to program, and inherently linked to the frequency domain. For many applications, a less complex time-domain model is desired, and considerable work has previously been performed on this topic. Unfortunately, existing low-order response models are not particularly accurate. These models are derived using simplifying assumptions that lose many of the salient features of the flow physics. This paper derives a second-order model directly from the Berg and Tijdeman solution and the model accurately describes the physical characteristics of the dominant response harmonic. The model is modified for application to both laminar and turbulent flow conditions. Frequency- and step-response comparisons are presented to demonstrate that the derived second-order model has superior response fidelity. Accuracies of model predictions are validated by a series of laboratory step-response experiments.