Evaluating the Effect of Vane Trailing Edge Flow on Turbine Rim Sealing

2020 ◽  
Vol 142 (8) ◽  
Author(s):  
Iván Monge-Concepción ◽  
Reid A. Berdanier ◽  
Michael D. Barringer ◽  
Karen A. Thole ◽  
Christopher Robak
Keyword(s):  
Navier Stokes ◽  
Trailing Edge ◽  
Cooling Flow ◽  
Flow Features ◽  
Purge Flow ◽  
Overall Efficiency ◽  
Carbon Dioxide Co2 ◽  
Cavity Cooling ◽  
Cooling Air ◽  
Edge Flow

Abstract Modern gas turbine development continues to move toward increased overall efficiency, driven in part by higher firing temperatures that point to a need for more cooling air to prevent catastrophic component failure. However, using additional cooling flow bled from the upstream compressor causes a corresponding detriment to overall efficiency. A primary candidate for cooling flow optimization is purge flow, which contributes to sealing the stator–rotor cavity and prevents ingestion of hot main gas path (MGP) flow into the wheelspace. Previous research has identified that the external main gas path flow physics play a significant role in driving rim seal ingestion. However, the potential impact of other cooling flow features on ingestion behavior, such as vane trailing edge (VTE) flow, is absent in the open literature. This paper presents experimental measurements of rim cavity cooling effectiveness collected from a one-stage turbine operating at engine-representative Reynolds and Mach numbers. Carbon dioxide (CO2) was used as a tracer gas in both the purge flow and vane trailing edge flow to investigate flow migration into and out of the wheelspace. Results show that the vane trailing edge flow does in fact migrate into the rim seal and that there is a superposition relationship between individual cooling flow contributions. Computational fluid dynamics (CFD) simulations using unsteady Reynolds-averaged Navier–Stokes (URANS) were used to confirm VTE flow ingestion into the rim seal cavity. Radial and circumferential traverse surveys were performed to quantify cooling flow radial migration through the main gas path with and without vane trailing edge flow. The surveys confirmed that vane trailing edge flow is entrained into the wheelspace as purge flow is reduced. Local CO2 measurements also confirmed the presence of VTE flow deep in the wheelspace cavity.

Evaluating the Effect of Vane Trailing Edge Flow on Turbine Rim Sealing

2019 ◽  
Author(s):  
Iván Monge-Concepción ◽  
Reid A. Berdanier ◽  
Michael D. Barringer ◽  
Karen A. Thole
Keyword(s):  
Tracer Gas ◽  
Trailing Edge ◽  
Cooling Flow ◽  
Flow Features ◽  
Purge Flow ◽  
Overall Efficiency ◽  
Carbon Dioxide Co2 ◽  
Cavity Cooling ◽  
Cooling Air ◽  
Edge Flow

Abstract Modern gas turbine development continues to move toward increased overall efficiency, driven in part by higher firing temperatures that point to a need for more cooling air to prevent catastrophic component failure. However, using additional cooling flow bled from the upstream compressor causes a corresponding detriment to overall efficiency. A primary candidate for cooling flow optimization is purge flow, which contributes to sealing the stator-rotor cavity and prevents ingestion of hot main gas path flow into the wheelspace. Previous research has identified that the external main gas path flow physics play a significant role in driving rim seal ingestion. However, the potential impact of other cooling flow features on ingestion behavior, such as vane trailing edge (VTE) flow, is absent in the open literature. This paper presents experimental measurements of rim cavity cooling effectiveness collected from a one-stage turbine operating at engine-representative Reynolds and Mach numbers. Carbon dioxide (CO2) was used as a tracer gas in both the purge flow and vane trailing edge flow to investigate flow migration into and out of the wheelspace. Results show that the vane trailing edge flow does in fact migrate into the rim seal and that there is a superposition relationship between individual cooling flow contributions. Radial and circumferential traverse surveys were performed to quantify cooling flow radial migration through the main gas path with and without vane trailing edge flow. The surveys confirmed that vane trailing edge flow is entrained into the wheelspace as purge flow is reduced. Local CO2 measurements also confirmed the presence of VTE flow deep in the wheelspace cavity.

scholarly journals Flow and windage due to bolts on a rotating disc

2016 ◽  
Vol 231 (15) ◽  
pp. 2925-2941
Author(s):  
Sulfickerali Noor Mohamed ◽  
John Chew ◽  
Nick Hills
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Time Dependent ◽  
Navier Stokes ◽  
Rotating Disc ◽  
Rotating Machine ◽  
Flow Features ◽  
Rotor Surface ◽  
Dynamics Simulations ◽  
Cooling Air

The cooling air in a rotating machine is subject to windage as it passes over the rotor surface, particularly for cases where nonaxisymmetric features such as boltheads are encountered. The ability to accurately predict windage can help reduce the quantity of cooling air required, resulting in increased efficiency. Previous work has shown that the steady computational fluid dynamics solutions can give reasonable predictions for the effects of bolts on disc moment for a rotor–stator cavity with throughflow but flow velocities and disc temperature are not well predicted. Large fluctuations in velocities have been observed experimentally in some cases. Time-dependent computational fluid dynamics simulations reported here bring to light the unsteady nature of the flow. Unsteady Reynolds-averaged Navier–Stokes calculations for 120° and 360° models of the rotor–stator cavity with 9 and 18 bolts were performed in order to better understand the flow physics. Although the rotor–stator cavity with bolts is geometrically steady in the rotating frame of reference, it was found that the bolts generate unsteadiness which creates time-dependent rotating flow features within the cavity. At low throughflow conditions, the unsteady flow significantly increases the average disc temperature.

Phantom Cooling of Nozzle Trailing Edge Discharge on Blade Surface and Platform

2014 ◽  
Author(s):  
Xueying Li ◽  
Jing Ren ◽  
Hongde Jiang
Keyword(s):  
Secondary Flows ◽  
Blade Surface ◽  
Suction Surface ◽  
Trailing Edge ◽  
Cooling Effectiveness ◽  
Cooling Flow ◽  
Discharge Velocity ◽  
Cooling Design ◽  
Cooling Air ◽  
Triangular Zone

Phantom cooling is defined as the cooling redistribution on airfoil surfaces and endwalls due to airfoil cooling discharges and leakages. Understanding of this effect has become especially critical in recent years, because of the restricted amount of cooling air for the achievement of higher efficiency. The phantom cooling effect of the first stage nozzle trailing edge discharge on the first stage blade surfaces and platform are studied numerically with URANS. Both time-dependent and time-averaged cooling effectiveness distributions on the rotor under the influence of vane trailing edge discharge are presented with different discharge velocity ratios. The results show that the nozzle trailing edge ejection affects the suction and pressure side cooling of the blade as well as the platform. The effects on the triangular zones of suction surface are evident, especially the bottom and top zones which are better cooled. Under the influence of passage secondary flows and rotating, different coolant discharge velocity ratios which resulted in different inlet angles have an effect on the phantom cooling distribution. In general, the cooling air discharged from the trailing edge of the first stage nozzle influences the temperature distribution on the blade, which can substantially improve the cooling efficiency in the bottom triangular zone. This suggests that accounting for phantom cooling can improve the cooling design and if actively controlled save cooling flow.

Asymptotic analysis of a linearized trailing edge flow

1972 ◽  
Vol 6 (3) ◽  
pp. 327-347 ◽  
Author(s):  
K. Capell
Keyword(s):  
Boundary Layer ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Wake Region ◽  
Trailing Edge ◽  
Navier Stokes Equations ◽  
Uniform Shear ◽  
Uniform Shear Flow ◽  
Appl Math ◽  
Edge Flow

An Oseén type linearization of the Navier-Stokes equations is made with respect to a uniform shear flow at the trailing edge of a flat plate. Asymptotic expansions are obtained to describe a symmetrical merging flow for distances from the trailing edge that are, in a certain sense, large. Expansions for three regions are found:(i) a wake region,(ii) an inviscid region, and(iii) an upstream lower order boundary layer.The results are compared with those of Hakkinen and O'Neil (Douglas Aircraft Co. Report, 1967) and Stewartson (Proc. Roy. Soc. Ser. A 306 (1968)). They are further related to the results of Stewartson (Mathematika 16 (1969)) and Messiter (SIAM J. Appl. Math. 18 (1970)).

scholarly journals A Machine Learning Approach to Improve Turbulence Modelling from DNS Data Using Neural Networks

2021 ◽  
Vol 6 (2) ◽  
pp. 17
Author(s):  
Yuri Frey Marioni ◽  
Enrique Alvarez de Toledo Ortiz ◽  
Andrea Cassinelli ◽  
Francesco Montomoli ◽  
Paolo Adami ◽  
...  
Keyword(s):  
Machine Learning ◽  
Neural Networks ◽  
Model Development ◽  
Turbulent Channel Flow ◽  
Boussinesq Approximation ◽  
Machine Learning Algorithms ◽  
Navier Stokes ◽  
Cooling Flow ◽  
Machine Learning Approach ◽  
Flow Features

In this paper, we investigate the feasibility of using DNS data and machine learning algorithms to assist RANS turbulence model development. High-fidelity DNS data are generated with the incompressible Navier–Stokes solver implemented in the spectral/hp element software framework Nektar++. Two test cases are considered: a turbulent channel flow and a stationary serpentine passage, representative of internal turbo-machinery cooling flow. The Python framework TensorFlow is chosen to train neural networks in order to address the known limitations of the Boussinesq approximation and a clustering based on flow features is run upfront to enable training on selected areas. The resulting models are implemented in the Rolls-Royce solver HYDRA and a posteriori predictions of velocity field and wall shear stress are compared to baseline RANS. The paper presents the fundamental elements of procedure applied, including a brief description of the tools and methods and improvements achieved.

Trailing-Edge Flow

2018 ◽  
Author(s):  
Anatoly I. Ruban
Keyword(s):  
Stokes Equations ◽  
Navier Stokes ◽  
Trailing Edge ◽  
Displacement Effect ◽  
Navier Stokes Equations ◽  
Reynolds Number Flow ◽  
Number Flow ◽  
High Reynolds ◽  
Interaction Problem ◽  
Edge Flow

Chapter 3 focuses on the high-Reynolds number flow of an incompressible fluid near the trailing edge of a flat plate. It begins with Goldstein’s (1930) solution for a viscous wake behind the plate, and shows that the displacement effect of the wake produces a singular pressure gradient near the trailing edge. It further shows that this singularity leads to a formation triple-deck viscous-inviscid interaction region that occupies a small vicinity of the trailing edge. A detailed analysis of the flow in each tier of the triple-deck structure is conducted based on the asymptotic analysis of the Navier–Stokes equations. As a result, the so-called ‘interaction problem’ is formulated. It concludes with the numerical solution of so-called ‘interaction problem’.

Modeling of Compressor Drum Cavities With Radial Inflow

2016 ◽  
Author(s):  
D. Amirante ◽  
Z. Sun ◽  
J. W. Chew ◽  
N. J. Hills ◽  
N. R. Atkins
Keyword(s):  
Thermal Stratification ◽  
Turbulence Modeling ◽  
Navier Stokes ◽  
Inflow Rate ◽  
Cfd Models ◽  
Flow And Heat Transfer ◽  
Rotating Discs ◽  
Computational Fluid Dynamics Cfd ◽  
Inlet Conditions ◽  
Cooling Air

Reynolds-Averaged Navier-Stokes (RANS) computations have been conducted to investigate the flow and heat transfer between two co-rotating discs with an axial throughflow of cooling air and a radial bleed introduced from the shroud. The computational fluid dynamics (CFD) models have been coupled with a thermal model of the test rig, and the predicted metal temperature compared with the thermocouple data. CFD solutions are shown to vary from a buoyancy driven regime to a forced convection regime, depending on the radial inflow rate prescribed at the shroud. At a high radial inflow rate, the computations show an excellent agreement with the measured temperatures through a transient rig condition. At a low radial inflow rate, the cavity flow is destabilized by the thermal stratification. Good qualitative agreement with the measurements is shown, although a significant over-prediction of disc temperatures is observed. This is associated with under prediction of the penetration of the axial throughflow into the cavity. The mismatch could be the result of strong sensitivity to the prescribed inlet conditions, in addition to possible shortcomings in the turbulence modeling.

Effect of riblets on the drag of a body of revolution with trailing-edge flow separation

1998 ◽  
Vol 33 (1) ◽  
pp. 135-139
Author(s):  
S. F. Konovalov ◽  
Yu. A. Lashkov ◽  
V. V. Mikhailov
Keyword(s):  
Flow Separation ◽  
Body Of Revolution ◽  
Trailing Edge ◽  
Edge Flow

Viscous tails in Hele-Shaw flow

1971 ◽  
Vol 46 (3) ◽  
pp. 569-576
Author(s):  
C. J. Wood
Keyword(s):  
Reynolds Number ◽  
Trailing Edge ◽  
Kutta Condition ◽  
Quantitative Discrepancy ◽  
Edge Flow ◽  
Hele Shaw Cell

An experiment has been performed, using pulsed dye injection on an aerofoil in a Hele-Shaw cell. The purpose was to observe the form of the trailing-edge flow when the Reynolds number was high enough to permit separation and the initiation of a Kutta condition. The experiment provides a successful confirmation of the existence of a ‘viscous tail’ as predicted by Buckmaster (1970) although there is an unexplained quantitative discrepancy.

Analysis of Blunt Trailing Edge Airfoils

2003 ◽  
Author(s):  
K. J. Standish ◽  
C. P. van Dam
Keyword(s):  
Experimental Data ◽  
Wind Turbine ◽  
Turbine Blades ◽  
Navier Stokes ◽  
Computational Techniques ◽  
Wind Turbine Blades ◽  
Trailing Edge ◽  
Blunt Trailing Edge ◽  
Large Wind ◽  
Structural Volume

The adoption of blunt trailing edge airfoils for the inner regions of large wind turbine blades has been proposed. Blunt trailing edge airfoils would not only provide increased structural volume, but have also been found to improve the lift characteristics of airfoils and therefore allow for section shapes with a greater maximum thickness. Limited experimental data makes it difficult for wind turbine designers to consider and conduct tradeoff studies using these section shapes. This lack of experimental data precipitated the present analysis of blunt trailing edge airfoils using computational fluid dynamics. Several computational techniques are applied including a viscous/inviscid interaction method and several Reynolds-averaged Navier-Stokes methods.

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