Research Papers

Transport of Entropy Waves Within a High Pressure Turbine Stage

[+] Author and Article Information
Paolo Gaetani

Politecnico di Milano,
Dipartimento di Energia,
Laboratorio di Fluidodinamica delle Macchine
Via Lambruschini, 4,
Milano 20158, Italy
e-mail: paolo.gaetani@polimi.it

Giacomo Persico

Politecnico di Milano,
Dipartimento di Energia,
Laboratorio di Fluidodinamica delle Macchine
Via Lambruschini, 4,
Milano 20158, Italy
e-mail: giacomo.persico@polimi.it

1Corresponding author.

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received September 19, 2018; final manuscript received November 29, 2018; published online January 16, 2019. Editor: Kenneth Hall.

J. Turbomach 141(3), 031006 (Jan 16, 2019) (9 pages) Paper No: TURBO-18-1254; doi: 10.1115/1.4042165 History: Received September 19, 2018; Revised November 29, 2018

This paper presents the results of an experimental study on the transport of entropy waves within a research turbine stage, representative of the key aero-thermal phenomenon featuring the combustor-turbine interaction in aero-engines. The entropy waves are injected upstream of the turbine by a dedicated entropy wave generator (EWG) and are released in axial direction; they feature circular shape with peak amplitude in the center and exhibit sinusoidal-like temporal evolution over the whole wave area. The maximum over-temperature amounts to 7% of the undisturbed flow, while the frequency is 30 Hz. The entropy waves are released in four azimuthal positions upstream of the stage, so to simulate four different burner-to-stator blade clocking. Time-resolved temperature measurements were performed with fast microthermocouples (FTC); the flow and the pressure field upstream and downstream of the stator and the rotor was measured with five-hole pneumatic probes and fast-response aerodynamic pressure probes. The entropy waves are observed to undergo a relevant attenuation throughout their transport within the stator blade row, but they remain clearly visible at the stator exit and retain their dynamic characteristics. In particular, the total temperature distribution appears severely altered by burner-stator clocking position. At the stage exit, the entropy waves loose their coherence, appearing spread in the azimuthal direction to almost cover the entire pitch in the outer part of the channel, while being more localized below midspan. Despite the severe and unsteady interaction of the entropy waves within the rotor, they retain their original dynamic character. A comparison with measurements performed by injecting steady hot streaks is finally reported, remarking both differences and affinities. As a relevant conclusion, it is experimentally shown that entropy waves can be proficiently simulated by considering a succession of hot streaks of different amplitude.

Copyright © 2019 by ASME
Your Session has timed out. Please sign back in to continue.


Sharma, O. P. , Pickett, G. F. , and Ni, R. H. , 1992, “ Assessment of Unsteady Flow in Turbines,” ASME J. Turbomach., 114(1), pp. 79–90. [CrossRef]
Butler, T. , Sharma, O. P. , Joslyn, H. , and Dring, R. , 1989, “ Redistribution of an Inlet Temperature Distortion in an Axial Flow Turbine Stage,” AIAA J. Propuls. Power, 5(1), pp. 64–71. [CrossRef]
Dorney, D. J. , and Sondak, D. L. , 2000, “ Effects of Tip Clearance on Hot Streak Migration in a High Subsonic Single Stage Turbine,” ASME J. Turbomach., 122(4), pp. 613–620. [CrossRef]
An, B. , Liu, J. , and Jiang, H. , 2009, “ Numerical Investigation on Unsteady Effects of Hot Streak on Flow and Heat Transfer in a Turbine Stage,” ASME J. Turbomach., 131(3), p. 031015. [CrossRef]
Knoblock, K. , Neuhaus, L. , Bake, F. , Gaetani, P. , and Persico, G. , 2017, “ Experimental Assessment of Noise Generation and Transmission in a High-Pressure Transonic Turbine Stage,” ASME J. Turbomach., 139, p. 101006. [CrossRef]
Munk, M. , and Prim, R. C. , 1947, “ On the Multiplicity of Steady Gas Flows Having the Same Streamline Pattern,” Proc. Natl. Acad. Sci. U. S. A., 33(5), pp. 137–141. [CrossRef] [PubMed]
Hawthorne, W. R. , 1974, “ Secondary Vorticity in Stratified Compressible Fluids in Rotating Systems,” University of Cambridge, Cambridge, UK, Report No. CUEDA-Turbo TR63.
Giles, M. B. , and Saxer, A. P. , 1994, “ Predictions of Three-Dimensional Steady and Unsteady Inviscid Transonic Stator/Rotor Interaction With Inlet Radial Temperature Nonuniformity,” ASME J. Turbomach., 116(3), pp. 347–357. [CrossRef]
Ong, J. , and Miller, R. J. , 2012, “ Hot Streak and Vane Coolant Migration in a Downstream Rotor,” ASME J. Turbomach., 134(5), p. 051002. [CrossRef]
Gaetani, G. , and Persico, G. , 2017, “ Hot Streak Evolution in an Axial HP Turbine Stage,” Int. J. Turbomach., Propul. Power, 2(2), p. 6. [CrossRef]
Koupper, C. , Bonneau, G. , and Gicquel, L. , 2016, “ Large Eddy Simulation of the Combustor Turbine Interface: Study of the Potential and Clocking Effects,” ASME Paper No. GT2016-56443.
Jacobi, S. , Mazzoni, C. , Chana, K. , and Rosic, B. , 2017, “ Investigation of Unsteady Flow Phenomena in the First Vane Caused by the Combustor Flow With Swirl,” ASME J. Turbomach., 139(4), p. 041006. [CrossRef]
Gaetani, P. , Persico, G. , Spinelli, A. , Sandu, C. , and Niculescu, F. , 2015, “ Entropy Wave Generator for Indirect Combustion Noise Experiments in a High-Pressure Turbine,” 11th European Turbomachinery Conference, Madrid, Spain, Mar. 23–27, Paper No. ETC2015-025. https://www.euroturbo.eu/publications/proceedings-papers/etc2015-025/
Persico, G. , Gaetani, P. , and Spinelli, A. , 2017, “ Assessment of Synthetic Entropy Waves for Indirect Combustion Noise Experiments in Gas Turbines,” Exp. Therm Fluid Sci., 88, pp. 376–388. [CrossRef]
Gaetani, P. , Persico, G. , Dossena, V. , and Osnaghi, C. , 2007, “ Investigation of the Flow Field in a High-Pressure Turbine Stage for Two Stator-Rotor Axial Gaps—Part I: Three-Dimensional Time-Averaged Flow Field,” ASME J. Turbomach., 129(3), pp. 572–579. [CrossRef]
Gaetani, P. , Persico, G. , and Spinelli, A. , 2017, “ Coupled Effect of Expansion Ratio and Blade Loading on the Aerodynamics of a High-Pressure Gas Turbine,” Appl. Sci., 7(3), p. 259. [CrossRef]
Persico, G. , Gaetani, P. , and Osnaghi, C. , 2009, “ A Parametric Study of the Blade Row Interaction in a High Pressure Turbine Stage,” ASME J. Turbomach., 131(3), p. 031006. [CrossRef]
Gaetani, P. , Persico, G. , and Osnaghi, C. , 2010, “ Effects of Axial Gap on the Vane-Rotor Interaction in a Low Aspect Ratio Turbine Stage,” AIAA J. Propuls. Power, 26(2), pp. 325–334. [CrossRef]
Persico, G. , Mora, A. , Gaetani, P. , and Savini, M. , 2012, “ Unsteady Aerodynamics of a Low Aspect Ratio Turbine Stage: Modeling Issues and Flow Physics,” ASME J. Turbomach., 134(6), p. 061030. [CrossRef]
Persico, G. , Gaetani, P. , and Guardone, A. , 2005, “ Design and Analysis of New Concept Fast-Response Pressure Probes,” Meas. Sci. Technol., 16(9), pp. 1741–1750. [CrossRef]
Kundu, P. K. , Cohen, I. M. , and Dowling, D. R. , 2012, Fluid Mechanics, 5th ed., Academic Press, Waltham, MA.


Grahic Jump Location
Fig. 1

Meridional cut of the test section; T0, T1, T2 = stage-inlet, stator-exit, stage-exit traverses; EWG: entropy wave generator

Grahic Jump Location
Fig. 2

Amplitude of temperature oscillations in the entropy wave at the stage inlet (T0). Injector aligned with the stator leading edge.

Grahic Jump Location
Fig. 3

Flow field downstream of the stator (T1): (a) total pressure loss, (b) streamwise vorticity, (c) absolute flow angle, and (d) Mach number

Grahic Jump Location
Fig. 4

Amplitude of EW temperature oscillations at the stator-exit for the four different injector-stator clocking positions, made nondimensional with respect to the maximum of the entropy wave at the stator inlet reported in Fig. 2 (in Celsius)

Grahic Jump Location
Fig. 5

Entropy wave time evolution for the PS case

Grahic Jump Location
Fig. 6

Time-averaged flow field in the relative frame downstream of the rotor

Grahic Jump Location
Fig. 7

Total temperature field downstream of the rotor. Stage inlet total temperature = 50 °C.

Grahic Jump Location
Fig. 8

Temperature fluctuations at the rotor exit made nondimensional with respect to the inlet maximum temperature fluctuation (represented in Fig. 2), for the four EW injection positions

Grahic Jump Location
Fig. 9

Temperature difference with respect to the case without injection at the rotor exit, for hot streak injection (taken from Ref. [10])

Grahic Jump Location
Fig. 10

Time-evolution of the entropy wave at the rotor-exit for stator midpitch injection



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