| description abstract | Three comprehensive mechanistic models (Ashford and Pierce, 1974; Sachdeva et al., 1986; Perkins, 1990) dealing with multiphase flow through chokes have been studied. Their common purpose is to determine the flow through a choke under both critical and subcritical flow. Except for their initial assumptions, these three models are basically the same and all are based on the energy equation. Performance of the model developed by Perkins (1990) was the best in a comparison test against a database of 1239 points. The other two models deviated up to 40 percent when compared to the Perkins model for large values of choke to pipe size ratios. A very important application of these models is in prediction of the pressure either upstream or downstream of the choke, given the flow rate through the choke and the known pressure. Pressure predictions against the flow direction (i.e., upstream of the choke) were foundto be in very good agreement with measurements. Not more than 13 percent average absolute error and 17 percent standard deviation were observed. Similar errors were reported for the downstream pressure predictions for data in the subcritical flow regime. However, downstream pressure predictions for data in the critical flow regime gave large errors, up to 40 percent, which were expected. | |
