Computational Investigation of A Volume Flow Meter Design

Abstract

Investigation of instantaneous wall pressure in a volume flow meter design has been carried out. The focus of the study was to obtain spectral analysis of the differential pressure between two pressure transducers. The following Reynolds numbers, based on bulk velocity and pipe diameter, have been studied; 17 000, 46 000, 92 000 and 150 000. The following models were used; SST, SST SAS and SST DES. Several researchers have contributed to the development of these model. F.R Menter was the original formulator of SST, which the other two models are extensions of. Menter are principally behind the SST SAS model. The concept of DES originated with P.R Spalart, but have since been worked on by many researchers including Spalart.

Six different grids were employed, ranging from 300 000 to 2 250 000 grid cells. Grid dependence for SST were investigated using four of the grids. Grid dependence for mean velocity was found to be within 1.5 percent for the grids investigated.

Time-averaged flow data were examined. The averaging time was found to be too short to exhibit statistical steadiness of second moment statistics for the SAS model. Instantaneous flow data were presented qualitatively for the DES model, using axial contour plots, and quantitatively for both DES and SAS models , using one-point spectra of fluctuating velocity. Distributions of mean skin-friction and mean wall pressure coefficient for the SST model were presented. It was further shown that the SST model alone is not able to produce wall pressure fluctuations, but that SAS and DES are. Spectral analysis of instantaneous differential pressure between the two pressure transducers were carried out for Re = 46 000, 92 000, 150 000. An increase in bulk velocity was found to increase the level of spectral amplitude of instantaneous wall pressure. The flow calculations and data analysis were not accurate and extensive enough to provide a more detailed relation.