Aerodynamic Optimization of High-Pressure Turbines for Lean-Burn Combustion System

2013 ◽  
Vol 135 (5) ◽  
Author(s):  
Shahrokh Shahpar ◽  
Stefano Caloni
Keyword(s):  
High Pressure ◽  
Swirling Flow ◽  
The Novel ◽  
Aerodynamic Optimization ◽  
Lean Burn ◽  
Flow Swirl ◽  
Optimization Study ◽  
Computational Fluid Dynamics Cfd ◽  
Multipoint Approximation ◽  
Optimization Methodology

Modern lean-burn combustors make use of high flow swirl to maintain flame stability. The swirling flow can persist downstream of the turbine first vane, changing the loading on the rotor, leading to a reduction in efficiency. This paper presents the results of an automatic optimization study carried out to mitigate the effect of high swirling flow on a high pressure turbine stage. A high-fidelity computational fluid dynamics (CFD)-based design optimization using a multipoint approximation (response surface) method is carried out to produce a new vane and a new rotor configuration with a significantly improved aerodynamic performance. It is demonstrated that the novel optimization methodology can cope well with a number of near equality constraints needed for a practical design.

Aerodynamic Optimisation of High Pressure Turbines for Lean-Burn Combustion System

2012 ◽  
Author(s):  
Shahrokh Shahpar ◽  
Stefano Caloni
Keyword(s):  
High Pressure ◽  
Swirling Flow ◽  
High Fidelity ◽  
Flame Stability ◽  
The Novel ◽  
Turbine Stage ◽  
Lean Burn ◽  
Flow Swirl ◽  
Surface Method ◽  
Practical Design

Modern lean-burn combustors make use of high flow swirl to maintain flame stability. The swirling flow can persist downstream of the turbine first vane, changing the loading on the rotor, leading to a reduction in efficiency. This paper presents the results of an automatic optimisation study carried out to mitigate the effect of high swirling flow on a high pressure turbine stage. A high-fidelity CFD-based design optimisation using a multi-point approximation (response surface) method is carried-out to produce a new vane and a new rotor configuration with a significantly improved aerodynamic performance. It is demonstrated that the novel optimisation methodology can cope well with a number of near equality constraints needed for a practical design.

Analysis of Radial Migration of Hot-Streak in Swirling Flow Through High-Pressure Turbine Stage

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
B. Khanal ◽  
L. He ◽  
J. Northall ◽  
P. Adami
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Swirling Flow ◽  
Guide Vane ◽  
Lean Burn ◽  
Considerable Impact ◽  
Computational Fluid Dynamics Cfd ◽  
Nozzle Guide ◽  
Hot Streak ◽  
Computational Analyses

The high pressure (HP) turbine is subject to inlet flow nonuniformities resulting from the combustor. A lean-burn combustor tends to combine temperature variations with strong swirl and, although considerable research efforts have been made to study the effects of a circumferential temperature nonuniformity (hot-streak), there is relatively little known about the interaction between the two. This paper presents a numerical investigation of the transonic test HP stage MT1 behavior under the combined influence of the swirl and hot-streak. The in house Rolls-Royce HYDRA numerical computational fluid dynamics (CFD) suite is used for all the simulations of the present study. Baseline configurations with either hot-streak or swirl at the stage inlet are analyzed to assess the methodology and to identify reference performance parameters through comparisons with the experimental data. Extensive computational analyses are then carried out for the cases with hot-streak and swirl combined, including both the effects of the combustor-nozzle guide vane (NGV) clocking and the direction of the swirl. The present results for the combined hot-streak and swirl cases reveal distinctive radial migrations of hot fluid in the NGV and rotor passages with considerable impact on the aerothermal performance. It is illustrated that the blade heat transfer characteristics and their dependence on the clocking position can be strongly affected by the swirl direction. A further computational examination is carried out on the validity of a superposition of the influences of swirl and hot-streak. It shows that the blade heat transfer in a combined swirl and hot-streak case cannot be predicted by the superposition of each in isolation.

Adiabatic Effectiveness on High Pressure Turbine Nozzle Guide Vanes Under Realistic Swirling Conditions

2018 ◽  
Author(s):  
T. Bacci ◽  
R. Becchi ◽  
A. Picchi ◽  
B. Facchini
Keyword(s):  
High Pressure ◽  
Film Cooling ◽  
Swirling Flow ◽  
Cooling System ◽  
Density Ratio ◽  
Leading Edge ◽  
Suction Side ◽  
Flame Stabilization ◽  
Lean Burn ◽  
Relevant Effect

In modern lean burn aero-engine combustors, highly swirling flow structures are adopted to control the fuel-air mixing and to provide the correct flame stabilization mechanisms. Aggressive swirl fields and high turbulence intensities are hence expected in the combustor-turbine interface. Moreover, to maximize the engine cycle efficiency, an accurate design of the high pressure nozzle cooling system must be pursued: in a film cooled nozzle the air taken from last compressor stages is ejected through discrete holes drilled on vane surfaces to provide a cold layer between hot gases and turbine components. In this context, the interactions between the swirling combustor outflow and the vane film cooling flows play a major role in the definition of a well performing cooling scheme, demanding for experimental campaigns at representative flow conditions. An annular three-sector combustor simulator with fully cooled high pressure vanes has been designed and installed at THT Lab of University of Florence. The test rig is equipped with three axial swirlers, effusion cooled liners and six film cooled high pressure vanes passages, for a vortex-to-vane count ratio of 1:2. The relative clocking position between swirlers and vanes has been chosen in order to have the leading edge of the central airfoil aligned with the central swirler. In this experimental work, adiabatic film effectiveness measurements have been carried out in the central sector vanes, in order to characterize the film-cooling performance under swirling inflow conditions. The Pressure Sensitive Paint technique, based on heat and mass transfer analogy, has been exploited to catch highly detailed 2D distributions. Carbon dioxide has been used as coolant in order to reach a coolant-to-mainstream density ratio of 1.5. Turbulence and five hole probe measurements at inlet/outlet of the cascade have been carried out as well, in order to highlight the characteristics of the flow field passing through the cascade and to provide precise boundary conditions. Results have shown a relevant effect of the swirling mainflow on the film cooling behaviour. Differences have been found between the central airfoil and the adjacent ones, both in terms of leading edge stagnation point position and of pressure and suction side film coverage characteristics.

Optimization of Piecewise Conical Nozzles: Theory and Application

2019 ◽  
Vol 141 (12) ◽  
Author(s):  
Karsten Hasselmann ◽  
Stefan aus der Wiesche ◽  
Eugeny Y. Kenig
Keyword(s):  
Flow Separation ◽  
Design Method ◽  
The Novel ◽  
Conical Nozzle ◽  
Measured Velocity ◽  
Separation Criterion ◽  
Pressure Distributions ◽  
Optimization Study ◽  
Computational Fluid Dynamics Cfd ◽  
Separation Number

An optimization study based on computational fluid dynamics (CFD) in combination with Stratford's analytical separation criterion was developed for the design of piecewise conical contraction zones and nozzles. The risk of flow separation was formally covered by a newly introduced dimensionless separation number. The use of this separation number can be interpreted as an adaption of Stratford's separation criterion to piecewise conical nozzles. In the nozzle design optimization process, the risk of flow separation was reduced by minimizing the separation number. It was found that the flow-optimized piecewise conical nozzle did not correspond to a direct geometric approximation of an ideal polynomial profile. In fact, it was beneficial to reduce the flow deflection in the outlet region for a piecewise conical nozzle to increase the nozzle performance. In order to validate the novel design method, extensive tests for different nozzle designs were conducted by means of wind tunnel tests. The measured velocity profiles and wall pressure distributions agreed well with the CFD predictions.

scholarly journals Multi-Disciplinary Design Optimisation of the Cooled Squealer Tip for High Pressure Turbines

Aerospace ◽  
2018 ◽  
Vol 5 (4) ◽  
pp. 116
Author(s):  
Stefano Caloni ◽  
Shahrokh Shahpar ◽  
Vassili Toropov
Keyword(s):  
Stress Level ◽  
Computer Aided Design ◽  
Turbine Rotor ◽  
The Novel ◽  
Design Optimisation ◽  
Aerodynamic Loss ◽  
Computational Fluid Dynamics Cfd ◽  
Multipoint Approximation ◽  
Aided Design ◽  
Novel Design

The turbine tip geometry can significantly alter the performance of the turbine stage; its design represents a challenge for a variety of reasons. Multiple disciplines are involved in its design and their requirements limit the creativity of the designer. Multi-Disciplinary Design Optimisation (MDO) offers the capability to improve the performance whilst satisfying all the design constraints. This paper presents a novel design of a turbine tip achieved via MDO techniques. A fully parametrised Computer-Aided Design (CAD) model of the turbine rotor is used to create the squealer geometry and to control the location of the cooling and dust holes. A Conjugate Heat Transfer Computational Fluid Dynamics (CFD) analysis is performed for evaluating the aerothermal performance of the component and the temperature the turbine operates at. A Finite Element (FE) analysis is then performed to find the stress level that the turbine has to withstand. A bi-objective optimisation reduces simultaneously the aerodynamic loss and the stress level. The Multipoint Approximation Method (MAM) recently enhanced for multi-objective problems is chosen to solve this optimisation problem. The paper presents its logic in detail. The novel geometry offers a significant improvement in the aerodynamic performance whilst reducing the maximum stress. The flow associated with the new geometry is analysed in detail to understand the source of the improvement.

Adiabatic Effectiveness on High-Pressure Turbine Nozzle Guide Vanes Under Realistic Swirling Conditions

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Tommaso Bacci ◽  
Riccardo Becchi ◽  
Alessio Picchi ◽  
Bruno Facchini
Keyword(s):  
High Pressure ◽  
Film Cooling ◽  
Swirling Flow ◽  
Cooling System ◽  
Density Ratio ◽  
Leading Edge ◽  
Suction Side ◽  
Flame Stabilization ◽  
Lean Burn ◽  
Relevant Effect

In modern lean-burn aero-engine combustors, highly swirling flow structures are adopted to control the fuel-air mixing and to provide the correct flame stabilization mechanisms. Aggressive swirl fields and high turbulence intensities are hence expected in the combustor-turbine interface. Moreover, to maximize the engine cycle efficiency, an accurate design of the high-pressure nozzle cooling system must be pursued: in a film-cooled nozzle, the air taken from last compressor stages is ejected through discrete holes drilled on vane surfaces to provide a cold layer between hot gases and turbine components. In this context, the interactions between the swirling combustor outflow and the vane film cooling flows play a major role in the definition of a well-performing cooling scheme, demanding for experimental campaigns at representative flow conditions. An annular three-sector combustor simulator with fully cooled high-pressure vanes has been designed and installed at THT Lab of University of Florence. The test rig is equipped with three axial swirlers, effusion-cooled liners, and six film-cooled high-pressure vanes passages, for a vortex-to-vane count ratio of 1:2. The relative clocking position between swirlers and vanes has been chosen in order to have the leading edge of the central airfoil aligned with the central swirler. In this experimental work, adiabatic film effectiveness measurements have been carried out in the central sector vanes, in order to characterize the film-cooling performance under swirling inflow conditions. The pressure-sensitive paint (PSP) technique, based on heat and mass transfer analogy, has been exploited to catch highly detailed 2D distributions. Carbon dioxide has been used as coolant in order to reach a coolant-to-mainstream density ratio of 1.5. Turbulence and five-hole probe measurements at inlet/outlet of the cascade have been carried out as well, in order to highlight the characteristics of the flow field passing through the cascade and to provide precise boundary conditions. Results have shown a relevant effect of the swirling mainflow on the film cooling behavior. Differences have been found between the central airfoil and the adjacent ones, both in terms of leading edge stagnation point position and of pressure and suction side film coverage characteristics.

scholarly journals Design of Novel Flash Ironmaking Reactors for Greatly Reduced Energy Consumption and CO2 Emissions

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 332
Author(s):  
Hong Yong Sohn ◽  
De-Qiu Fan ◽  
Amr Abdelghany
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Large Diameter ◽  
Reduction Reaction ◽  
The Novel ◽  
Height Ratio ◽  
Fine Iron ◽  
Computational Fluid Dynamics Cfd ◽  
High Reduction ◽  
Iron Ore Concentrate

The development of a novel ironmaking technology based on fine iron ore concentrate in a flash reactor is summarized. The design of potential industrial reactors for flash ironmaking based on the computational fluid dynamics technique is described. Overall, this simulation work has shown that the size of the reactor used in the novel flash ironmaking technology (FIT) can be quite reasonable vis-à-vis the blast furnaces. A flash reactor of 12 m diameter and 35 m height with a single burner operating at atmospheric pressure would produce 1.0 million tons of iron per year. The height can be further reduced by either using multiple burners, preheating the feed gas, or both. The computational fluid dynamics (CFD)-based design of potential industrial reactors for flash ironmaking pointed to a number of features that should be incorporated. The flow field should be designed in such a way that a larger portion of the reactor is used for the reduction reaction but at the same time excessive collision of particles with the wall must be avoided. Further, a large diameter-to-height ratio that still allows a high reduction degree should be used from the viewpoint of decreased heat loss. This may require the incorporation of multiple burners and solid feeding ports.

scholarly journals Morphological and Hemodynamic Changes during Cerebral Aneurysm Growth

2021 ◽  
Vol 11 (4) ◽  
pp. 520
Author(s):  
Emily R. Nordahl ◽  
Susheil Uthamaraj ◽  
Kendall D. Dennis ◽  
Alena Sejkorová ◽  
Aleš Hejčl ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Kinetic Energy ◽  
Swirling Flow ◽  
Morphological Changes ◽  
Cerebral Aneurysms ◽  
Patient Specific ◽  
Aneurysm Wall ◽  
Aneurysm Growth ◽  
Computational Fluid Dynamics Cfd

Computational fluid dynamics (CFD) has grown as a tool to help understand the hemodynamic properties related to the rupture of cerebral aneurysms. Few of these studies deal specifically with aneurysm growth and most only use a single time instance within the aneurysm growth history. The present retrospective study investigated four patient-specific aneurysms, once at initial diagnosis and then at follow-up, to analyze hemodynamic and morphological changes. Aneurysm geometries were segmented via the medical image processing software Mimics. The geometries were meshed and a computational fluid dynamics (CFD) analysis was performed using ANSYS. Results showed that major geometry bulk growth occurred in areas of low wall shear stress (WSS). Wall shape remodeling near neck impingement regions occurred in areas with large gradients of WSS and oscillatory shear index. This study found that growth occurred in areas where low WSS was accompanied by high velocity gradients between the aneurysm wall and large swirling flow structures. A new finding was that all cases showed an increase in kinetic energy from the first time point to the second, and this change in kinetic energy seems correlated to the change in aneurysm volume.

CAD AND CAE TECHNOLOGIES OF A NOVEL PLANE SIX-BAR SWAYING MACHINE

2008 ◽  
Vol 07 (01) ◽  
pp. 65-67
Author(s):  
CHANGPING ZOU ◽  
LI DU ◽  
XIANDE HUANG
Keyword(s):  
High Pressure ◽  
Kinetic Analysis ◽  
Rotational Speed ◽  
Preliminary Analysis ◽  
Unit Weight ◽  
The Novel ◽  
Parameterized Modeling ◽  
New Type ◽  
Working Principle ◽  
Key Dimensions

A new type of six-bar swaying machine was put forward, which is an ingenious combination of plane multi-bar mechanism and high pressure oil cylinder. Preliminary analysis shows that this machine has many advantages, such as the torque produced by its unit weight, its small size, its light deadweight, etc. Thus it can be applied to situations that need swaying mechanism with low rotational speed and great torque. Firstly, the mechanism composition and working principle of the swaying machine were introduced. Secondly, parameterized modeling of the mechanism was carried out by utilizing software ADAMS. Then kinematic analysis and kinetic analysis were completed by using ADAMS. Finally, key dimensions were adjusted according to kinetic analysis. These tasks are believed to be beneficial to the development of the novel transmission.

The Novel Complex[LRuIV(μ-O)3RuIVL][PF6]2·H2O–a Molecular Section of the Structures of BaRuIVO3(High-Pressure Phase) and Ba5/6Sr1/6RuIVO3

1989 ◽  
Vol 28 (6) ◽  
pp. 763-765 ◽  
Author(s):  
Peter Neubold ◽  
Beatriz S. P. C. Della Vedova ◽  
Karl Wieghardt ◽  
Bernd Nuber ◽  
Johannes Weiss
Keyword(s):  
High Pressure ◽  
High Pressure Phase ◽  
The Novel ◽  
Novel Complex ◽  
Pressure Phase
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