Optical instrumentation for fluid flow in gas turbines

Both a novel shearing interferometer and the first demonstration of particle image velocimetry (PIV) to the stator-rotor gap of a spinning turbine cascade are presented. Each of these techniques are suitable for measuring gas turbine representative flows. The simple interferometric technique has been demonstrated on a compressor representative flow in a 2-D wind tunnel. The interferometer has obvious limitations, as it requires a clear line of sight for the integration of refractive index along an optical path. Despite this, it is a credible alternative to schlieren or shadowgraph in that it provides both qualitative visualisation and a quantitative measurement of refractive index and the variables to which it is dependent without the vibration isolation requirements of beam splitting interferometry. The 2-D PIV measurements have been made in the stator-rotor gap of the MTI high-pressure turbine stage within DERA's Isentropic Light Piston Facility (lLPF). The measurements were made at full engine representative conditions adjacent to a rotor spinning at 8200 rpm. This is a particularly challenging application due to the complex geometry and random and periodic effects generated as the stator wake interacts with the adjacent spinning rotor. The application is further complicated due to the transient nature of the facility. The measurements represent a 2- D, instantaneous, quantitative description of the unsteady flow field and reveal evidence of shocks and wakes. The estimated accuracy after scaling, timing, particle centroid and particle lag errors have been considered is ± 5%. Non-smoothed, non-time averaged measurements are qualitatively compared with a numerical prediction generated using a 2-D unsteady flow solver (prediction supplied by DERA). A very close agreement has been achieved. A novel approach to characterising the third component of velocity from the diffraction rings of a defocusing particle viewed through a single camera has been explored. This 3-D PIV technique has been demonstrated on a nozzle flow but issues concerning the aberrations of the curved test section window of the turbine cascade could not be resolved in time for testing on the facility. Suggestions have been made towards solving this problem. Recommendations are also made towards the eventual goal of revealing a temporally and spatially resolved 3-D velocity distribution of the stator wake impinging on the passing rotor

Collective excitations of atomic Bose-Einstein condensates

We apply linear-response analysis of the Gross-Pitaevskii equation to obtain the excitation frequencies of a Bose-Einstein condensate confined in a time-averaged orbiting potential trap. Our calculated values are in excellent agreement with those observed in a recent experiment.Comment: 11 pages, 2 Postscript figures, uses psbox.tex for automatic figure inclusion. More info at http://amo.phy.gasou.edu/bec.htm

Incorporating Mythic and Interpretive Analysis in the Investigation of Hearing Loss on the Family Farm

Despite knowing about the dangers of hearing loss, farmers typically choose not to protect their hearing. Examining the myth of farm life, this study aims to discern whether rhetorical myths influence farmers\u27 decisions to wear hearing protection. Researchers conducted 40 interviews with farmers regarding farm life and hearing loss. Results suggest that farmers typically do not use hearing protection; their answers reflect the myths of sacrifice and safety. Analysis demonstrates that knowledge of the relationship between myth and practice should impact future attempts to change farmers\u27 behavior

The effect of levonorgestrel intrauterine device placement on serum CA‐125 levels in healthy premenopausal women

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135190/1/ijgo179.pd

William Gillette and American Theatrical Realism of the Late Nineteenth Century

This thesis, entitled William Gillette and American Theatrical Realism of the Late Nineteenth Century studies the realistic staging techniques employed by William Gillette during the latter part of the nineteenth century in order to bring recognition and establish William Gillette as an innovator in the realistic staging of drama during the time in American theatre known as the movement toward realism. The study examines four plays written and staged by William Gillette which range both in chronology of production and importance to the movement: those plays being Held By The Enemy, Secret Service, Sherlock Holmes, and Electricity. Using these plays, a style of realistic staging, which includes lighting, sound, scenic design, costuming, and dialogue are examined through careful use of the scripts, reviews of the plays from periodicals of the time, and history books which recorded highlights of the era