Boundary Layer Development in Axial Compressors and Turbines: Part 2 of 4—Compressors

Halstead, David E.; Wisler, D. C.; Okiishi, T. H.; Walker, G. J.; Hodson, H. P.; Shin, Hyun Wook

doi:10.1115/1.2841142

Cited by 74 publications

(53 citation statements)

References 5 publications

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“…Also, errors of 20% or more arise when hot films calibrated in a laminar flow are used to measure a turbulent flow. The hot film sensors were used on the aft part of suction surfaces and were therefore likely to see laminar, turbulent, calmed and separated flow at different positions of the upstream rotor, see Halstead et al [17] or Banieghbal et al [18]. Calibration for all these conditions would be extremely difficult and quite probably impossible.…”

Section: Methodsmentioning

confidence: 99%

Boundary Layer Development in the BR710 and BR715 LP Turbines—The Implementation of High-Lift and Ultra-High-Lift Concepts

Howell

Hodson

Schulte

et al. 2002

Journal of Turbomachinery

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This paper describes a detailed study into the unsteady boundary layer behaviour in two high lift and one ultra high lift Rolls-Royce Deutschland LP turbines. The objectives of the paper are to show that high lift and ultra high-lift concepts have been successfully incorporated into the design of these new LP turbine profiles.Measurements from surface mounted hot film sensors were made in full size, cold flow test rigs at the altitude test facility at Stuttgart University. The LP turbine blade profiles are thought to be state of the art in terms of their lift and design philosophy. The two high lift profiles represent slightly different styles of velocity distribution. The first high-lift profile comes from a two stage LP turbine (the BR710 cold-flow, high-lift demonstrator rig). The second high-lift profile tested is from a three-stage machine (the BR715 LPT rig). The ultra-high lift profile measurements come from a redesign of the BR715 LP turbine: this is designated the BR715UHL LP turbine. This ultra high-lift profile represents a 12% reduction in blade numbers compared to the original BR715 turbine.The results from NGV2 on all of the turbines show "classical" unsteady boundary layer behaviour. The measurements from NGV3 (of both the BR715 and BR715UHL turbines) are more complicated, but can still be broken down into classical regions of wake-induced transition, natural transition and calming. The wakes from both upstream rotors and NGVs interact in a complicated manner, affecting the suction surface boundary layer of NGV3. This has important implications for the prediction of the flows on blade rows in multistage environments.

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Section: Methodsmentioning

confidence: 99%

Boundary Layer Development in the BR710 and BR715 LP Turbines—The Implementation of High-Lift and Ultra-High-Lift Concepts

Howell

Hodson

Schulte

et al. 2002

Journal of Turbomachinery

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“…With low or moderate kinematic perturbation by the impinging wakes, the induction of Klebanoff distortions is similar as with mean steady flow, as observed experimentally by, e.g., Liu and Rodi [25] and by Orth [26]. A general description of the transition under wake paths and in between wake paths was given by Halstead et al [27][28][29][30] for axial turbomachines, based on tests covering a broad range of Reynolds numbers and loading levels, but always with a sufficiently high level of background turbulence such that natural transition did not occur. Figure 1 is a schematic of the different zones in a time-space diagram (t = time; x = streamwise distance along the blade surface).…”

Section: Wake-induced Transitionmentioning

confidence: 72%

Transition Models for Turbomachinery Boundary Layer Flows: A Review

Dick

Kubacki

2017

IJTPP

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Current models for transition in turbomachinery boundary layer flows are reviewed. The basic physical mechanisms of transition processes and the way these processes are expressed by model ingredients are discussed. The fundamentals of models are described as far as possible, with a common structure of the equations and with emphasis on the similarities between the models. Tests of models reported in the literature are summarized and our own test is added. A conclusion on the performance of models is formulated.Keywords: turbomachinery flows; transition models; boundary layers; bypass transition; separationinduced transition; wake-induced transition; Reynolds-averaged Navier-Stokes; intermittency; laminar kinetic energy Transition MechanismsWith the objective of modelling with Reynolds-averaged Navier-Stokes (RANS) or URANS (unsteady or time-accurate RANS) description of a flow, generally, four types of transition from laminar state to turbulent state in turbomachinery boundary layer flows are distinguished [1,2]. These are: natural transition in attached boundary layer state, bypass transition in attached boundary layer state under a statistically steady mean flow, separation-induced transition in the free shear layer formed by separation of a boundary layer under a statistically steady mean flow, and wake-induced transition due to periodically unsteady impact of wakes on boundary layers in attached or separated state. Despite the vast amount of studies on these transition types during the last 4 or 5 decades, understanding of the mechanisms is still not complete, although large progress has been made in the last decade thanks to direct numerical simulation (DNS) and large-eddy simulation (LES). Hereafter, we summarise the mean mechanisms, taking into account the inherent limitations of modelling with Reynolds-averaged Navier-Stokes description of a flow. This means that secondary effects, which mostly are the least understood and sometimes still are a matter of controversy, are not discussed, because, anyhow these features cannot be represented by RANS or URANS. Natural TransitionUnder a statistically steady mean flow of low turbulence level, transition in an attached boundary layer is initiated by 2D viscosity-dependent Tollmien-Schlichting instability waves, followed by a 3D instability, leading to formation of spanwise periodic hairpin vortices, which, farther downstream, cause breakdown of the laminar layer with generation of turbulent spots. These spots finally merge resulting in the formation of a turbulent boundary layer [1,2]. This type of transition is called natural transition. It is a rather slow process and, under a very low mean-flow turbulence level, as in external Int.

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“…The study presented and interpreted the data from the surface hot film probes and the boundary layer survey for baseline operating conditions. The study by Halstead et al (1995) has contributed to better understanding the flow physics through an LP-turbine component.…”

Section: Turbine Stage Investigationsmentioning

confidence: 99%

“…In a four-part study, Halstead et al (1995) investigated the boundary layer development in axial compressors and turbines. Part 3 of the study focused on unsteady flow and the effects of the wakes on the performance of LP-turbines.…”

Section: Turbine Stage Investigationsmentioning

confidence: 99%

Aerodynamic and Performance Behavior of a Three-Stage High Efficiency Turbine at Design and Off-Design Operating Points

Schobeiri¹,

Gilarranz²,

Johansen³

2004

The International Journal of Rotating Machinery

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This article deals with the aerodynamic and performance behavior of a three-stage high pressure research turbine with 3-D curved blades at its design and off-design operating points. The research turbine configuration incorporates six rows beginning with a stator row. Interstage aerodynamic measurements were performed at three stations, namely downstream of the first rotor row, the second stator row, and the second rotor row. Interstage radial and circum-ferential traversing presented a detailed flow picture of the middle stage. Performance measurements were carried out within a rotational speed range of 75% to 116% of the design speed. The experimental investigations have been carried out on the recently established multi-stage turbine research facility at the Turbomachinery Performance and Flow Research Laboratory, TPFL, of Texas A&M University. Keywords Development in the field of turbomachinery computational fluid dynamics (CFD) has reached an advanced level that allows a detailed computation of the complex three-dimensional viscous flow field through a turbomachinery stage using Navier-Stokes codes. Numerous published cases demonstrate the capability of different CFD-methods to calculate various flow quantities in a remarkably detailed fashion. The efficiency and loss calculations, however, reveal noticeable disagreement between the experimental and computational results. The detailed 3-D flow pictures delivered by viscous flow solvers display the source and location of the total pressure losses and entropy distribution within the blade channel, particularly at the blade hub and tip regions. Based on these results, the turbine aerodynamicist is able to reconfigure the blade geometry to reduce the profile and the secondary flow losses. The latter is especially relevant for high pressure (HP) turbine design with relatively small aspect ratios where the secondary flow losses significantly contribute to the reduction of the stage efficiency. In recent years, the power generation turbine manufacturers have been increasingly focus-ing their efforts on reducing the secondary flow losses of HP-turbine blades by implementing the information obtained from the Navier-Stokes flow simulations. To account for the discrepancy mentioned above, the Navier-Stokes codes are frequently calibrated. The calibration process may provide a temporary matching solution for cases in which experimental results are available. However, it is not appropriate for a priori predicting of the efficiency of new designs. The disagreement between the Navier-Stokes based efficiency calculations and the measurements , however, does not allow the engine manufacturer to issue efficiency and performance guaranty without thoroughly testing their new design. Considering the physical aspects of the computation , among other things, two major issues may be considered primarily responsible for the above discrepancy, namely the turbulence modeling and the modeling of the laminar-turbulent boundary layer transition process. The latter directly impacts the a...

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Boundary Layer Development in Axial Compressors and Turbines: Part 2 of 4—Compressors

Cited by 74 publications

References 5 publications

Boundary Layer Development in the BR710 and BR715 LP Turbines—The Implementation of High-Lift and Ultra-High-Lift Concepts

Boundary Layer Development in the BR710 and BR715 LP Turbines—The Implementation of High-Lift and Ultra-High-Lift Concepts

Transition Models for Turbomachinery Boundary Layer Flows: A Review

Aerodynamic and Performance Behavior of a Three-Stage High Efficiency Turbine at Design and Off-Design Operating Points

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