An assessment was conducted to determine the suitability of subscale, low-Mach-number, particle image velocimetry (PIV) testing and computational fluid dynamics (CFD) analysis to evaluate swirling flow downstream of a swirl pattern generation system composed of continuous patterns of turning vanes. Successful demonstration of the evaluation methods required acceptable comparison of the PIV and CFD to an independent five-hole probe measurement performed at the design Mach number and full-scale geometry. The focus of the investigation was on direct comparison of flow angles and flow features one diameter downstream of the swirl pattern generator. Both the subscale PIV and the CFD provide adequate representation of the swirling flow produced by the full-scale generator. The subscale PIV and CFD may be used to predict the performance of the full-scale swirl pattern generator and allow for inexpensive testing and analysis to be performed during the design process, thus improving the accuracy of generating a desired swirl pattern.

No abstract

The flowfield of the L1A low pressure (LP) turbine blade subjected to traversing upstream wakes was experimentally and computationally investigated at an inlet Reynolds number of 25,000. The L1A profile is a high-lift aft-loaded low pressure turbine blade design. The profile was designed to separate at low Reynolds numbers making it an ideal airfoil for use in flow separation control studies. This study applied a new two-dimensional CFD model to the L1A LP turbine blade design using a three-equation eddy-viscosity type transitional flow model developed by Walters and Leylek. Velocity field measurements were obtained by two-dimensional planer particle image velocimetry, and comparisons were made to the CFD predictions using the Walters and Leylek [13] k-kL-ω transitional flow model and the Menter’s [24] k-ω(SST) model. Hotwire measurements and pressure coefficient distributions were also used to compare each model’s ability to predict the wake produced from the wake generator, and the loading on the L1A LP turbine blade profile with unsteady wakes. These comparisons were used to determine which RANS CFD model could better predict the unsteady L1A blade flowfield at low inlet Reynolds number. This research also provided further characterization of the Walters and Leylek transitional flow model for low Reynolds number aerodynamic flow prediction in low pressure turbine blades.

The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS.

No abstract