Gas Turbine Blade Tip and Near Tip Heat Transfer with Film Cooling

Gas turbine blade tips experience very high thermal loads due to high temperature combustion gases and tip leakage flows. This leads to the tip region being very susceptible to experiencing failures. To better understand these effects, experiments were performed in a suction-type low speed wind tunnel cascade to determine heat transfer coefficients and film cooling effectiveness distributions on a highly-loaded 2-D gas turbine blade model in the tip and near-tip regions. The blade shape was generated to match the pressure coefficients of the operating turbine blade design. The model featured multiple tip and pressure side film cooling holes and a squealer tip geometry. The Reynolds number based on axial chord and cascade inlet velocity for all experiments was 80,000. The heat transfer coefficients and film cooling effectiveness values are presented for the tip, pressure side, and suction side at several blowing ratios for each view. The tip gap was fixed at .85% span for all experiments. Tip heat transfer coefficients are shown to be largest near the leading edge for all blowing ratios. Large differences exist in both the heat transfer coefficient and film cooling effectiveness contours between the upper two and the lower two blowing ratios as ―lift-off‖ of the tip purge jets is observed with increasing blowing ratio. Pressure side heat transfer coefficients show subtle differences in the form of increasing heat transfer coefficient with blowing ratio near and downstream of the coolant holes. Film cooling effectiveness is largest immediately downstream of the pressure side holes and on the suction side squealer rim. The suction side heat transfer coefficients exhibit only subtle differences with changes in blowing ratio. The film cooling effectiveness on the suction side is seen to gradually increase with blowing ratio; primarily in the region of the leakage vortex. Blowing ratio has a significant effect on the tip and pressure side heat transfer coefficients and film cooling effectiveness. While on the suction side, the effect is minimal on heat transfer coefficients, but significant on film cooling effectiveness

Use of a New Spirophosphine To Achieve Catalytic Enantioselective [4 + 1] Annulations of Amines with Allenes To Generate Dihydropyrroles

Due in part to the common occurrence of five-membered nitrogen heterocycles in bioactive molecules, the discovery of methods for the enantioselective synthesis of such structures is a useful endeavor. Building on a single example by Tong of a phosphine-catalyzed [4 + 1] annulation of an amine with an allene that furnished an achiral dihydropyrrole in 22% yield, we have developed, with the aid of a new chiral spirophosphine catalyst, a method with increased utility, specifically, improved yield, enhanced scope (the use of γ-substituted allenes), and good ee. The enantioenriched dihydropyrrole products can be transformed into other interesting families of compounds with very good stereoselectivity

Genetic modifiers of cognitive maintenance among older adults.

ObjectiveIdentify genetic factors associated with cognitive maintenance in late life and assess their association with gray matter (GM) volume in brain networks affected in aging.MethodsWe conducted a genome-wide association study of ∼2.4 M markers to identify modifiers of cognitive trajectories in Caucasian participants (N = 7,328) from two population-based cohorts of non-demented elderly. Standardized measures of global cognitive function (z-scores) over 10 and 6 years were calculated among participants and mixed model regression was used to determine subject-specific cognitive slopes. "Cognitive maintenance" was defined as a change in slope of ≥ 0 and was compared with all cognitive decliners (slope < 0). In an independent cohort of cognitively normal older Caucasians adults (N = 122), top association findings were then used to create genetic scores to assess whether carrying more cognitive maintenance alleles was associated with greater GM volume in specific brain networks using voxel-based morphometry.ResultsThe most significant association was on chromosome 11 (rs7109806, P = 7.8 × 10(-8)) near RIC3. RIC3 modulates activity of α7 nicotinic acetylcholine receptors, which have been implicated in synaptic plasticity and beta-amyloid binding. In the neuroimaging cohort, carrying more cognitive maintenance alleles was associated with greater volume in the right executive control network (RECN; PFWE  = 0.01).ConclusionsThese findings suggest that there may be genetic loci that promote healthy cognitive aging and that they may do so by conferring robustness to GM in the RECN. Future work is required to validate top candidate genes such as RIC3 for involvement in cognitive maintenance

SCMR president's page

News from the Society for Cardiovascular Magnetic Resonanc

Business Warehouse Modeling Using SAP: Simulating A Business Case To Apply Strategic Enterprise Management To Accounting

The goal of this research project is to develop a simulation model specifically for the Management Accounting Information Systems course – an SAP enabled course for junior Accounting majors at Saint Joseph's University. The purpose of this simulation is to present students with a set of business scenarios, and have the students make a knowledgeable decision using SAP Business Warehouse software. The scenarios will act as a simplified replication of the business environment; thus, they will provide the students with an integrated learning experience. They will make business decisions to ensure the profitability and cash flow of a corporation. While making these decisions, students participate in the application and analysis provided by PC4YOU, which is a simulated company within SAP for demonstration and education purposes. Eventually, the students will need to justify the existence of their strategic plans by evaluating benefits of the system using the reporting tools available within SAP. To provide a “learning by doing” experience, the scenarios will be used to demonstrate the reporting functionality within PC4YOU, the simulated company integrated into the SAP SEM system. Today’s global economy is putting a premium on the ability of students to evaluate a broad range of decisions in collaboration with adaptive supply chains. A critical component of the evolving accounting curriculum lies in the ability to extend students beyond the numbers to evaluate the effective and efficient delivery of these supply chains

Static Ricci-flat 5-manifolds admitting the 2-sphere

We examine, in a purely geometrical way, static Ricci-flat 5-manifolds admitting the 2-sphere and an additional hypersurface-orthogonal Killing vector. These are widely studied in the literature, from different physical approaches, and known variously as the Kramer - Gross - Perry - Davidson - Owen solutions. The 2-fold infinity of cases that result are studied by way of new coordinates (which are in most cases global) and the cases likely to be of interest in any physical approach are distinguished on the basis of the nakedness and geometrical mass of their associated singularities. It is argued that the entire class of solutions has to be considered unstable about the exceptional solutions: the black string and soliton cases. Any physical theory which admits the non-exceptional solutions as the external vacuua of a collapsing object has to accept the possibility of collapse to zero volume leaving behind the weakest possible, albeit naked, geometrical singularities at the origin.Finally, it is pointed out that these types of solutions generalize, in a straightforward way, to higher dimensions.Comment: Generalize, in a straightforward way, to higher dimension

Precision timing of PSR J1012+5307 and strong-field GR tests

We report on the high precision timing analysis of the pulsar-white dwarf binary PSR J1012+5307. Using 15 years of multi-telescope data from the European Pulsar Timing Array (EPTA) network, a significant measurement of the variation of the orbital period is obtained. Using this ideal strong-field gravity laboratory we derive theory independent limits for both the dipole radiation and the variation of the gravitational constant.Comment: 3 pages, Proceedings of the 12th Marcel Grossmann Meeting on General Relativity (MG 12