ABSTRACT:The extensional viscosity for aqueous solutions of high molecular weight poly(acrylamide) copolymers and poly(ethylene oxide) homopolymers was measured using a laboratory-designed screen extensional rheometer. A Bingham model was developed to estimate the average local polymer coil extensional viscosity ( coil ). A strong correlation was found between the measured coil values and the polymer extensional viscosity predicted by a bead-spring model. The dilute aqueous solution drag reduction was measured with a rotating disk instrument under conditions minimizing the effects of shear degradation. Extensional viscosity and drag reduction measurements were performed in deionized water and in 0.514M sodium chloride. The relative drag reduction efficiency values (⌬) in both solvents were found to strongly correlate with measured coil values. This is the first report of the accurate prediction of drag reduction behavior for a wide range of polymer types in various solvents from the independently measured molecular parameters coil and []C. The often-used relative drag reduction efficiency expressed as the product of []C and ⌬ can now be replaced by the absolute drag reduction efficiency []C coil .

Extensional flow encountered by polymers used in reservoir flooding for EOR has been studied on a lab scale using flow through a series of 0.5 inch diameter woven mesh nylon screens. Dilute polymer solutions have been used as mobility control agents in EOR because of the high viscosity resulting from solutions undergoing extension. Polymer chemical composition, solvent quality, and molecular weight were found to affect extensional performance. A yield stress was measured for many of the polymers examined in this study indicating that not all polymers undergo extension at the low flow rates typical of EOR. Polymer FloodingAqueous polymer solutions are often used as displacing fluids employed during reservoir flooding. To be economical, the polymers must increase the flow resistance of the displacing fluid at concentrations as low as parts per million. 310

The interface between rotating and stationary components in a gas turbine is commonly called “disk cavities”. In pursuit of a performance benefit from Secondary Air Flow System (SAF) flow reduction, rotating/stationary disk cavity flow ingestion management in the turbine section becomes an important subject. To completely avoid ingestion, large amount of purging flow is utilized which reduces engine performance. Too much ingestion and the risk of reduced engine durability becomes an issue. Therefore, a partial ingestion condition is desired for optimizing SAF for performance. Typical methodology would be analysing purging flow using 3-D computational fluid dynamics (CFD) modeling in conjunction with engine test data to validate the design and ensure optimal SAF partial ingestion. This approach puts a very heavy demand on computational resources even at steady state. To extend the practice into a transient and unsteady flow field to attempt full design optimization will be even more taxing on computational resources and analysis labor time. An quick alternative would be using a 1-D flow solver for the task in conjunction with baseload main gas path circumferential pressure variation either from main flow path 3D CFD or engine test data. Unfortunately, currently there are no 1-D flow solvers can resolve the poly-directional nature of partial flow ingestion. This paper presents a quick and reliable alternative using a numerical method for augmenting a 1-D flow solver to resolve the partial flow ingestion situation. This is used in conjunction with the 1-D flow solver to resolve the bulk cavity temperature and heat transfer in the disk cavity. The results of this augmented 1-D flow solver show excellent agreement to field measurement data and 3-D CFD solutions. The tool enables a very realistic transient thermal analysis with partial flow ingestion at a fraction of the cost and analysis time of a full 3-D CFD analysis. This enables a faster design optimization with multiple iteration of a turbomachinery disk cavity with partial flow ingestion.