Effect of nozzle external geometry on the pressure and shear stress exerted on the surface being gaged in fluid dynamic gauging

PERALTA, J. M.; CHEW, Y.M.J.; WILSON, D. I.

Mar del Plata, Argentina

Congreso; VI Congreso Argentino de Ingeniería Química; 2010

Asociación Argentina de Ingenieros Químicos (AAIQ)

Fouling is the unwanted deposition of species from process fluids onto surfaces. Fluid dynamic gauging (FDG) is an experimental technique that exploits the behaviour of a suction flow through a nozzle located near a fouling deposit to determine the deposit’s thickness. The objective of this work was to study the effect of the shape of the external part of the nozzle on the shear stress and pressure profiles on the surface being gauged using computational fluid dynamics simulations. Different nozzle shapes were studied using a 2D axysimmetric computational domain. The operating conditions were set by using different values of mass flow rate through the nozzle. The minimum clearance between the nozzle (of internal diameter 20 mm) and the surface was set at 1 mm. Model validation, comprising mesh independency testing and comparisons with experimental pressure and theoretical shear stress profiles was performed. The results showed that certain desirable pressure and shear stress profiles can be obtained by using relatively simple external nozzle geometries.