The streamwise development of two-dimensional wall jets and other two-dimensional turbulent shear flows.

This thesis presents the formulation, evaluation and application of a method for predicting the streamwise development of turbulent shear flows, and the three chapters relate respectively to these three aspects of the work

THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS COMPUTATIONS OF FILM COOLING FOR THE LEADING EDGE REGION OF A TURBINE BLADE MODEL

ABSTRACT Computations of film cooling are presented based on the geometry of a UBC experimental turbine blade model. This model has a semi-circlar leading edge with four rows of laterally-inclined film cooling orifices positioned symmetrically about the stagnation line. The computational domain follows the physical domain and includes the curved blade surface as well as the coolant regions in the circular coolant orifices. The injection orifices are inclined spanwise at 30 0 to the blade surface. A multi-zone curvilinear grid is used to simulate the complex configuration. Grids are generated by a block-structured elliptic grid generation method which represents exactly the curved blade surface as well as the circular injection orifices. Computations over the cooled turbine blade model are carried out for overall mass flow ratios of 0.52 and 0.97. The relative mass flow ratios from each orifice are specified to match experimental values. Density ratios of coolant to free stream were taken to be unity (constant density). Comparison of predicted film cooling effectiveness with experimental data showed reasonable agreement

Multiple Jets in a Crossflow: Detailed Measurements and

ABSTRACT The fluid mechanics and heat transfer characteristics of film cooling is three-dimensional and highly complex. To better understand this problem, an experimental study was conducted in a low speed wind tunnel on a row of six rectangular jets injected at 900 to the crossflow (main stream flow). The jet-tocrossflow velocity ratios (blowing ratios) examined were 0.5, 1.0, and 1.5, and the jet spacing-to-jet width ratio was 3.0. No significant temperature difference between jet and crossflow air was introduced. Mean velocities, and six flow stresses were measured using a three-component laser Doppler velocimeter operating in coincidence-mode. Seeding of both jet and crossstream air was achieved with a commercially available smoke generator. Flow statistics are reported in the form of vector plots, contours, and x-y graphs, showing velocity, turbulence intensity, and Reynolds stresses. To complement the detailed measurements, flow visualization was accomplished by transmitting the laser beam through a cylindrical lens, thereby generating a narrow, intense sheet of light. Jet air only was seeded with smoke, which was illuminated in the plane of the light sheet. Therefore, it was possible to record on video tape the trajectory and penetration of the jets in the crossflow. Selected still images from the recordings are presented. Numerical simulations of the observed flow field were made by using a multi-grid, segmented, k-E CFD code. Special near wall treatment included a non-isotropic formulation for the effective viscosity, a low Re model for k, and an algebraic model for the length scale. Comparisons between the measured and computed velocities show good agreement for the non-uniform mean flow at the jet exit plane. Velocities and stresses on the jet centerline downstream of the orifice are less well predicted, probably because of inadequate turbulence modeling, while values off the centerline match those of the experiments much more closely

Anion Dependent Redox Changes in Iron Bis-terdentate Nitroxide {NNO} Chelates

The reaction of [Fe II(BF4)2]·6H2O with the nitroxide radical, 4,4-dimethyl-2,2-di(2-pyridyl) oxazolidine-N-oxide (L•), produces the mononuclear transition metal complex [FeII(L•)2](BF4)2 (1) which has been investigated using temperature dependent susceptibility, Mössbauer spectroscopy, electrochemistry, density functional theory (DFT) calculations, and X-ray structure analysis. Single crystal X-ray diffraction analysis and Mössbauer measurements reveal an octahedral low spin Fe2+ environment where the pyridyl donors from L• coordinate equatorially while the oxygen containing the radical from L• coordinates axially forming a linear O•··Fe(II)··O• arrangement. Magnetic susceptibility measurements show a strong radical-radical intramolecular antiferromagnetic interaction mediated by the diamagnetic Fe2+ center. This is supported by DFT calculations which show a mutual spatial overlap of 0.24 and a spin density population analysis which highlights the antiparallel spin alignment between the two ligands. Similarly the monocationic complex [FeIII(L-)2](BPh4)·0.5H2O (2)  has been fully characterized with Fe ligand and N-O bond length changes in the X-ray structure analysis, magnetic measurements revealing a Curie-like S = 1/2 ground state, electron paramagnetic resonance (EPR) spectra, DFT calculations, and electrochemistry measurements all consistent with assignment of Fe in the (III) state and both ligands in the L- form. 2 is formed by a rare, reductively induced oxidation of the Fe center, and all physical data are self-consistent. The electrochemical studies were undertaken for both 1 and 2, thus allowing common Fe-ligand redox intermediates to be identified and the results interpreted in terms of square reaction schemes

CCDC 925602: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures