Aero-thermal flow characterization downstream of an NGV cascade by five-hole probe and filtered Rayleigh scattering measurements

The characterization of pressure, temperature and velocity fields in turbomachinery flows typically relies on well-proven probe-based technology such as pneumatic probes, hot-wire sensors or thermocouples. These devices have to be introduced into narrow flow channels and by that obstruct part of the duct at the actual measuring position, which can significantly alter the aerodynamic performance of the components under investigation. In this contribution, measurement results of a commercially available five-hole probe with mounted temperature sensor and laser-optical-filtered Rayleigh scattering diagnostics are acquired downstream of a nozzle guide vane cascade with lean-burn combustion representative inlet flow distortions. Pressure results obtained by both methods are found to be on a similar absolute level. However, the unavoidable movement of optical elements following the facilities’ heat-up procedure prevents a sufficient sensitivity of pressure data obtained by filtered Rayleigh scattering and, therefore, an identification of certain flow structures related to probe interference on the static pressure field. Concerning temperature data, results of both methods, despite the probe data being shifted in lateral direction, are found to be in good agreement in topology as well as absolute level. The strongest intrusive influence of the probe body as well as a bias to probe readings in certain flow regions is identified when comparing velocity data by means of the optical Doppler frequency-shift. Whereas filtered Rayleigh scattering results follow a smooth and continuous trend, five-hole probe data are characterized by steep gradients inside the airfoil wakes as well as differing slopes in the flow passages. These findings are backed by a comparison of five-hole probe velocities with a CFD solution, revealing an erroneous reading of axial velocities inside the wake areas. The study concludes that the presented filtered Rayleigh scattering diagnostics, with estimated accuracies of 50–90 hPa, 2–3 K and 2–3 MHz in pressure, temperature and Doppler frequency-shift, is a viable alternative to conventional probe-based measuring approaches in characterizing the aero-thermal properties of turbomachinery flows.Graphical abstract

[1]  C. Boley,et al.  On the Kinetic Model Description of Rayleigh–Brillouin Scattering from Molecular Gases , 1974 .

[2]  B. Lakshminarayana,et al.  Mean velocity and decay characteristics of the guidevane and stator blade wake of an axial flow compressor , 1980 .

[3]  Walter R. Lempert,et al.  Two-dimensional measurement of density, velocity, and temperature in turbulent high-speed air flows by UV rayleigh scattering , 1990 .

[4]  Hiroshi Komine,et al.  Doppler Global Velocimetry: A New Way to Look at Velocity , 1991 .

[5]  David P. Towers,et al.  The Application of Particle Image Velocimetry (PIV)in a Short Duration Transonic Annular Turbine Cascade , 1992 .

[6]  J. N. Forkey,et al.  Development and Demonstration of Filtered Rayleigh Scattering: a Laser Based Flow Diagnostic for Planar Measurement of Velocity, Temperature and Pressure. , 1996 .

[7]  Mark P. Wernet,et al.  Development of digital particle imaging velocimetry for use in turbomachinery , 2000 .

[8]  J. Westerweel.  Experiments in Fluids , 2000 .

[9]  Christian Willert,et al.  Extension of Doppler global velocimetry to periodic flows , 2001 .

[10]  Richard B. Miles,et al.  Flow field imaging through sharp-edged atomic and molecular 'notch' filters , 2001 .

[11]  W. Sanz,et al.  Laser-optical investigation of turbine wake flow , 2003 .

[12]  Bernd Stoffel,et al.  Experimental investigations on steady wake effects in a high-lift turbine cascade , 2004 .

[13]  K. A. Elam,et al.  Time-average measurement of velocity, density, temperature, and turbulence velocity fluctuations using Rayleigh and Mie scattering , 2005 .

[14]  Christian E. Willert,et al.  Assessment of camera models for use in planar velocimetry calibration , 2006 .

[15]  Thomas Povey,et al.  HP Vane Aerodynamics and Heat Transfer in the Presence of Aggressive Inlet Swirl , 2011 .

[16]  R. Mailach,et al.  Investigation of the Tip Clearance Flow in a Compressor Cascade Using a Novel Laser Measurement Technique With High Temporal Resolution , 2012 .

[17]  Peter Jeschke,et al.  Measuring Failures and Correction Methods for Pneumatic Multi-Hole Probes , 2012 .

[18]  Melanie Voges,et al.  The challenge of stereo PIV measurements in the tip gap of a transonic compressor rotor with casing treatment , 2012 .

[19]  Heinz-Peter Schiffer,et al.  Investigation of the tip leakage flow at turbine rotor blades with squealer cavity , 2013 .

[20]  Thomas Povey,et al.  HP Vane Aerodynamics and Heat Transfer in the Presence of Aggressive Inlet Swirl , 2013 .

[21]  Vasudevan Kanjirakkad,et al.  A new experimental facility to investigate combustor-turbine interactions in gas turbines with multiple can combustors , 2014 .

[22]  Anders Lundbladh,et al.  LEMCOTEC: Improving the Core-Engine Thermal Efficiency , 2014 .

[23]  Marco Marengo,et al.  Oblique impacts of water drops onto hydrophobic and superhydrophobic surfaces: outcomes, timing, and rebound maps , 2014 .

[24]  Ulrich Doll,et al.  Endoscopic filtered Rayleigh scattering for the analysis of ducted gas flows , 2014 .

[25]  J. Aschenbruck,et al.  Influence of a Multi-Hole Pressure Probe on the Flow Field in Axial-Turbines , 2015 .

[26]  Bruno Facchini,et al.  Flowfield and Temperature Profiles Measurements on a Combustor Simulator Dedicated to Hot Streaks Generation , 2015 .

[27]  C. Willert,et al.  Methods to improve pressure, temperature and velocity accuracies of filtered Rayleigh scattering measurements in gaseous flows , 2016 .

[28]  Ulrich Doll,et al.  Temperature Measurements at the Outlet of a Lean Burn Single-Sector Combustor by Laser Optical Methods , 2016 .

[29]  Ulrich Doll,et al.  Flow Field Characterization at the Outlet of a Lean Burn Single Sector Combustor by Laser-Optical Methods , 2016 .

[30]  P. Jeschke,et al.  Numerical Studies on the Intrusive Influence of a Five-Hole Pressure Probe in a High-Speed Axial Compressor , 2017 .

[31]  Ulrich Doll,et al.  Pressure, temperature, and three-component velocity fields by filtered Rayleigh scattering velocimetry. , 2017, Optics letters.

[32]  A. Andreini,et al.  Impact of Predicted Combustor Outlet Conditions on the Aerothermal Performance of Film-Cooled HPT Vanes , 2018, Volume 5C: Heat Transfer.