Numerical Calibration of Mass Flow Plug for Inlet Testing

Abstract

A simple control volume model has been developed to calculate the discharge coefficient through a mass flow plug (MFP) and validated with a calibration experiment. The maximum error of the model within the operating region of the MFP is 0.54%. The control volume analysis developed work is comprised of a sequence of flow calculations through the MFP. The model uses the MFP geometry and operating pressure and temperature to couple continuity, momentum, energy, an equation of state, and wall shear. The discharge coefficient calculation also includes the effects of boundary layer growth, including the reduction in cross-sectional flow area as characterized by the boundary layer displacement thickness. The last calculation in the sequence uses an integral method to calculate the growth of the boundary layer, from which the displacement thickness is then determined. The result of these successive calculations is an accurate one-dimension model of the velocity, pressure, and temperature through the MFP. For comparison, a computational fluid dynamic (CFD) calibration is shown, which when compared to the presented numerical model, had a lower accuracy with a maximum error of 1.35% in addition to being slower by a factor of 100."

Effects of Distortion on Mass Flow Plug Calibration

“…These numerical calibration distributions are compared to the experimental distributions in Ref. 7. With the exception of the smallest area ratio, the distributions trend the same where the experimental discharge coefficient is slightly below the numerical value.…”

“…The details of the ASME nozzle and its calibration are found in Ref. 7. The discharge coefficient for the mass-flow plug is defined as:…”