Investigation of the Contamination Influence on the Parameters of Gas Flow Through Multihole Orifice Flowmeter

The aim of this article is to determine the contamination influence on the parameters of gas flow through multihole orifice (MHO) meter. The numerical investigations of the contamination influence for the MHO flow meters have not been reported in the previous researches. The air flow was steady, 3-D, and turbulent. The finite volume method was used for the purpose of numerical analyses. The main considered physical properties of air were density and dynamic viscosity. The standard $k-\varepsilon $ turbulence model was used. MHO meter with two different $\beta $ parameters was observed. Also, the influence of contamination formed in front of the MHO meter with the same $\beta $ parameters was analyzed. In order to qualitatively analyze the influence of the contamination, the 15 different combinations of contamination parameters for seven different Reynolds numbers were analyzed. The pressure drop, singular pressure loss coefficient, and discharge coefficient were analyzed. The grid sensitivity study was performed on four systematically refined numerical grids for MHO meter without contamination and the results were compared with the experimental results found in the literature. Also, the grid refinement was done for MHO meter with contamination for two different values of Reynolds number. It was found that for the same values of contamination angle, regardless of the contamination parameters ratio, the results were unchanged. Also, it was found that the contamination has an influence on the change of pressure drop values, which directly affects the change of other parameters. Pressure drop and singular pressure loss coefficient of the orifice with contamination are smaller compared to the values for a pure orifice, whereby the measurement accuracy was reduced. Also, for cases of contamination, the discharge coefficient was increased, leading to a negative measurement error. It was found that the same trend occurs regardless of the Reynolds number. It was found that the MHO meter was less sensitive to the pressure drop changes due to the increase of contamination angle in regard to the single-hole orifice meters.