Numerical investigation of the effects of overhead straight pipe distance on pressure loss in orifice

In this study, the effects of a chamfered orifice plate on permanent, incompressible and isothermal pipe flow are simulated with numerical solution. Flows are solved using Reynolds-avarage Navier stokes equations and SST turbulence model. The main purpose of the study was to reduce orifice pressure loses and shortening the length of the orifice upper flow straight pipe. Here, the effects of the orifice plate with the chamfer angle (0, 15, 30, 45, 60) on the pressure loss and flow read error are investigated for two different cases according to whether the chamfered side faces upflow and downflow of the orifice (left chamfered) and (right chamfered). First the standard orifice flow meter is calibrated with a long straight pipe flow in the orifice upper flow. Then, an obstacle was created in the orifice upper flow and the upper flow length was shortened. The effects of the deteriorating flow due to the obstacle on the flow reading of the standard orifice flow meter were measured at short distance. Orifice flows are analyzed in 5000, 15000, 25000, 40000 and 100000 Reynolds numbers. According to the numerical results, the chamfer angle on the right chamfered orifice has no effect on pressure loss and flow read error and is the same as the chamfered orifice. In the left chamfered orifice, pressure loss was found to be lowest at chamfer angles around 33 o and flow reading error was lowest at chamfer angles around 45 o. In this study, the effect of pressure difference measurement points on flow reading error in orifice meter was also investigated. It was observed that flow reading error decreases as pressure difference measurement points move away from orifice.