0
Research Papers

Parasitic Loss Due to Leading Edge Instrumentation on a Low-Pressure Turbine Blade

[+] Author and Article Information
Henry C.-H. Ng

Whittle Laboratory,
University of Cambridge,
Cambridge CB3 0DY, UK
e-mail: hchn2@cam.ac.uk

John D. Coull

Whittle Laboratory,
University of Cambridge,
Cambridge CB3 0DY, UK
e-mail: jdc38@cam.ac.uk

1Corresponding author.

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received August 30, 2016; final manuscript received September 14, 2016; published online January 10, 2017. Editor: Kenneth Hall.

J. Turbomach 139(4), 041007 (Jan 10, 2017) (10 pages) Paper No: TURBO-16-1218; doi: 10.1115/1.4035043 History: Received August 30, 2016; Revised September 14, 2016

During the testing of development engines and components, intrusive instrumentation such as Kiel-head pitot probes and shrouded thermocouples are used to evaluate gas properties and performance. The size of these instruments can be significant relative to the blades, and their impact on aerodynamic efficiency must be considered when analyzing the test data. This paper reports on such parasitic losses for instruments mounted on the leading edge of a stator in a low-pressure turbine, with particular emphasis on understanding the impact of probe geometry on the induced loss. The instrumentation and turbine blades have been modeled in a low Mach number cascade facility with an upstream turbulence grid. The cascade was designed so that the leading edge probes were interchangeable in situ, allowing for rapid testing of differing probe geometries. Reynolds-averaged Navier–Stokes (RANS) calculations were performed to complement the experiments and improve understanding of the flow behavior. A horseshoe vortex-like system forms at the join of the probe body and blade leading edge, generating pairs of streamwise vortices which convect over the blade pressure and suction surfaces. These vortices promote mixing between the freestream and boundary layer fluid and promote the transition of the boundary layer from laminar to turbulent flow. The size and shape of the leading edge probes relative to the blade vary significantly between applications. Tests with realistic probe geometries demonstrate that the detailed design of the shroud bleed system can impact the loss. A study of idealized cylinders is performed to isolate the impact of probe diameter, aspect ratio, and incidence. Beyond a probe aspect ratio of two, parasitic loss was found to scale approximately with probe frontal area.

Copyright © 2017 by ASME
Your Session has timed out. Please sign back in to continue.

References

Kiel, G. , 1935, “ Total-Head Meter With Small Sensitivity to Yaw,” NACA, Technical Note 775.
Russell, W. R. , Gracey, W. , Letko, W. , and Fournier, P. G. , 1951, “ Wind-Tunnel Investigation of Six Shielded Total-Pressure Tubes at High Angles of Attack Subsonic Speeds,” NACA, Technical Note 2530.
Gracey, W. , 1956, “ Wind-Tunnel Investigation of a Number of Total-Pressure Tubes at High Angles of Attack Subsonic,” NACA Transonic and Supersonic Speeds, Technical Note 3641.
Lepicovsky, J. , 2008, “ Effects of a Rotating Aerodynamic Probe on the Flow Field of a Compressor Rotor,” NASA, Technical Report No. NASA/CR–2008-215215.
Stieger, R. D. , and Hodson, H. P. , 2004, “ The Transition Mechanism of Highly Loaded Low Pressure Turbine Blades,” ASME J. Turbomach., 126(4), pp. 536–543. [CrossRef]
Drela, M. , 1985, “ Two-Dimensional Transonic Aerodynamic Design and Analysis Using the Euler Equations,” Ph.D. thesis, Massachusetts Institute of Technology, Cambridge, MA.
Youngren, H. , and Drela, M. , 1991, “ Viscous/Inviscid Method for Preliminary Design of Transonic Cascades,” AIAA Paper No. AIAA-91-2364-CP.
Roach, P. E. , 1987, “ The Generation of Nearly Isotropic Turbulence by Means of Grids,” Heat Fluid Flow, 8(2), pp. 82–92. [CrossRef]
Moinier, P. , and Giles, M. B. , 1998, “ Preconditioned Euler and Navier-Stokes Calculations on Unstructured Meshes,” 6th ICFD Conference on Numerical Methods for Fluid Dynamics, Oxford, UK, Mar.
Dargahi, B. , 1989, “ The Turbulent Flow Field Around a Circular Cylinder,” Exp. Fluids, 8(1), pp. 1–12. [CrossRef]
Williamson, C. H. K. , 1996, “ Vortex Dynamics in the Cylinder Wake,” Ann. Rev. Fluid Mech., 28(1), pp. 477–539. [CrossRef]
Kirkil, G. , and Constantinescu, G. , 2015, “ Effect of Cylinder Reynolds Number on the Turbulent Horseshoe Vortex System and Newar Wake of a Surface-Mounted Circular Cylinder,” Phys. Fluids, 27(7), p. 075102. [CrossRef]
Hunt, J. C. R. , Wray, A. A. , and Moin, P. , 1988, “ Eddies, Stream and Convergence Zones in Turbulent Flows,” Center for Turbulence Research, Stanford, CA, Report No. CTR-S88.
Broadwell, J. E. , and Breidenthal, R. E. , 1984, “ Structure and Mixing of a Transverse Jet in Incompressible Flow,” J. Fluid Mech., 148, pp. 405–412. [CrossRef]
Fric, T. F. , and Roshko, A. , 1994, “ Vortical Structure in the Wake of a Transverse Jet,” J. Fluid Mech., 279, pp. 1–47. [CrossRef]
Kelso, R. M. , Lim, T. T. , and Perry, A. E. , 1996, “ A Experimental Study of Round Jets in Cross-Flow,” J. Fluid Mech., 306, pp. 111–144. [CrossRef]
Haven, B. A. , and Kurosaka, M. , 1997, “ Kidney and Anti-Kidney Vortices in Crossflow Jets,” J. Fluid Mech., 352, pp. 27–64. [CrossRef]
Bunker, R. S. , 2005, “ A Review of Shaped Hole Turbine Film Cooling Technology,” ASME J. Hear Transfer, 127(4), pp. 441–453. [CrossRef]
Hoerner, F. S. , 1965, “ Fluid-Dynamic Drag: Theoretical, Experimental and Statistical Information,” Hoerner Fluid Dynamics, Bakersfield, CA.
Schubauer, G. B. , and Spangenberg, W. G. , 1960, “ Forced Mixing in Boundary Layers,” J. Fluid Mech., 8(1), pp. 10–32. [CrossRef]
Westphal, R. V. , Pauley, W. R. , and Eaton, J. K. , 1987, “ Interaction Between a Vortex and a Turbulent Boundary Layer—Part 1: Mean Flow Evolution and Turbulence Properties,” NASA, Report No. TM-88361.

Figures

Grahic Jump Location
Fig. 1

Sketch of the cascade with instrumented blade

Grahic Jump Location
Fig. 2

Measured blade static pressure distribution for uninstrumented vane (circles) and Mises target distribution (solid line)

Grahic Jump Location
Fig. 3

Plots of yaw angle and Yp taken at cascade midspan for passages adjacent to instrumented blade

Grahic Jump Location
Fig. 4

Mass-averaged Yp as a function of cell count showing baseline refinement levels for a clean vane and instrumented vane

Grahic Jump Location
Fig. 5

Mesh of instrumented vane and mesh details of realistic temperature probe

Grahic Jump Location
Fig. 6

Sketch of realistic probe models. Left: pressure probe and right: temperature probe.

Grahic Jump Location
Fig. 7

Left-to-right: contours of yaw angle, pitch angle, and Yp measured with a five-hole probe at cascade exit for uninstrumented vane: (a) yaw angle, (b) pitch angle, and (c) Yp

Grahic Jump Location
Fig. 8

Left-to-right: contours of yaw angle, pitch angle, and Yp measured with a five-hole probe at cascade exit for realistic pressure probes: (a) yaw angle, (b) pitch angle, and (c) Yp

Grahic Jump Location
Fig. 9

Left-to-right: contours of yaw angle, pitch angle, and Yp measured with a five-hole probe at cascade exit for realistic temperature probes: (a) yaw angle, (b) pitch angle, and (c) Yp

Grahic Jump Location
Fig. 10

Flow visualization for the realistic temperature probe

Grahic Jump Location
Fig. 11

Isosurfaces of Q colored by vorticity ((a) and (d)), viewing the LE probe from the suction side and pressure side, respectively. Corresponding isosurfaces of negative axial velocity ((b) and (e)) and corresponding surface streamlines ((c) and (f)).

Grahic Jump Location
Fig. 12

Contours of Yp for each test case. From left-to-right: (1) real temperature Kiel, (2) shroud bleed holes at 45 deg, (3) shroud bleed holes at 90 deg, (4) shroud bleed holes covered, and (5) solid cylinders.

Grahic Jump Location
Fig. 13

Schematic of probe incidence. Left: LE probe yaw angle relative to design and right: LE probe pitch angle relative to design.

Grahic Jump Location
Fig. 14

Contours of Yp for LE probe yaw angles as indicated

Grahic Jump Location
Fig. 15

Contours of Yp for LE probe pitch angles as indicated

Grahic Jump Location
Fig. 16

Mass-averaged Yp as a function of LE probe incidence relative to design inlet

Grahic Jump Location
Fig. 17

Mass-averaged Yp as a function of LE probe diameter. Constant probe length Lprobe/Cx=0.18.

Grahic Jump Location
Fig. 18

Mass-averaged Yp as a function of probe frontal area-to-passage area. Constant probe length Lprobe/Cx=0.18.

Grahic Jump Location
Fig. 19

Measured blade static pressure distribution for uninstrumented vane (circles), vane with Dprobe/Cx=0.03 probes mounted (squares and diamonds), and Mises target distribution (solid line)

Grahic Jump Location
Fig. 20

Flow visualization photos of suction side blade surface. Top: uninstrumented blade with separated region between (b) and (c). Bottom: LE probes of Dprobe/Cx=0.03 and Lprobe/Cx=0.18 mounted. LE probe locations indicated by white triangles in image. Note suppression of separation region in bottom photo.

Grahic Jump Location
Fig. 21

Blade static pressure distribution for increasing leading edge probe diameters and constant length Lprobe/Cx=0.18

Grahic Jump Location
Fig. 22

Mass-averaged Yp as a function of LE probe length. Increasing diameters as labeled.

Grahic Jump Location
Fig. 23

Blade static pressure distribution measured directly behind LE probes (left) and between LE probes (right), for increasing length (0.08<Lprobe/Cx<0.31) at constant diameters: Dprobe/Cx=0.10 (top) and 0.19 (bottom). Mises design intent plotted for reference.

Grahic Jump Location
Fig. 24

Mass-averaged Yp as a function of LE probe length aspect ratio. Probe diameters as labeled.

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In