scholarly journals Large Eddy Simulations of High Rossby Number Flow in the High Pressure Compressor Inter-Disk Cavity

2020 ◽  
Author(s):  
Deepak Saini ◽  
Richard D. Sandberg
Keyword(s):  
Outer Region ◽  
Large Eddy Simulations ◽  
Rossby Number ◽  
High Pressure Compressor ◽  
Large Eddy ◽  
Number Flow ◽  
Induced Flow ◽  
Inner Region ◽  
Buoyancy Induced Flow ◽  
Pressure Compressor

Abstract The focus of the present study is to understand the effect of Rayleigh number on a high Rossby number flow in a high pressure compressor (HPC) inter-disk cavity. These cavities form between the compressor disks of a gas turbine engine, and they are an integral part of the internal air cooling system. We perform highly resolved large eddy simulations for two Rayleigh numbers of 0.76 × 108 and 1.54 × 108 at a fixed Rossby number of 4.5 by solving the compressible Navier–Stokes equations. The results show a flow structure dominated by a toroidal vortex in the inner region of the cavity. In the outer region, the flow is observed to move radially outwards by Ekman layers formed on the side disks and to move radially inwards through the central core region of the cavity. An enhancement in the intensity of the radial flares is observed in the outer region of the cavity for the high Rayleigh number case with no perceivable effect in the inner region. The near shroud region is mostly dominated by the centrifugal buoyancy-induced flow and the wall Nusselt number calculated at the shroud is in close agreement with centrifugal buoyancy-induced flow without an axial bore flow.

scholarly journals LARGE EDDY SIMULATIONS OF HIGH ROSSBY NUMBER FLOW IN THE HIGH PRESSURE COMPRESSOR INTER-DISK CAVITY

2021 ◽  
pp. 1-22
Author(s):  
Deepak Saini ◽  
Richard Sandberg
Keyword(s):  
Rayleigh Number ◽  
Outer Region ◽  
Large Eddy Simulations ◽  
Rossby Number ◽  
Air Cooling ◽  
Large Eddy ◽  
Number Flow ◽  
Induced Flow ◽  
Inner Region ◽  
Buoyancy Induced Flow

Abstract The focus of the present study is to understand the effect of Rayleigh number on a high Rossby number flow in a high pres- sure compressor (HPC) inter-disk cavity. These cavities form between the compressor disks of a gas turbine engine, and they are an integral part of the internal air cooling system. We perform highly resolved large eddy simulations for two Rayleigh numbers of 0.76 × 108 and 1.54 × 108 at a fixed Rossby number of 4.5 by solving the compressible Navier–Stokes equations. The results show a flow structure dominated by a toroidal vortex in the inner region of the cavity. In the outer region, the flow is observed to move radially outwards by Ekman layers formed on the side disks and to move radially inwards through the central core region of the cavity. An enhancement in the intensity of the radial flares is observed in the outer region of the cavity for the high Rayleigh number case with no perceivable effect in the inner region. The near shroud region is mostly dominated by the centrifugal buoyancy-induced flow and the wall Nusselt number calculated at the shroud is in close agreement with centrifugal buoyancy-induced flow without an axial bore flow.

Measurement and Analysis of Buoyancy-Induced Heat Transfer in Aero-Engine Compressor Rotors

2020 ◽  
Author(s):  
Richard W. Jackson ◽  
Dario Luberti ◽  
Hui Tang ◽  
Oliver J. Pountney ◽  
James A. Scobie ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Three Dimensional ◽  
Outer Region ◽  
Conjugate Problem ◽  
Radial Temperature ◽  
Nusselt Numbers ◽  
Induced Flow ◽  
Aero Engines ◽  
Inner Region ◽  
Buoyancy Induced Flow

Abstract The flow inside cavities between co-rotating compressor discs of aero-engines is driven by buoyancy, with Grashof numbers exceeding 1013. This phenomenon creates a conjugate problem: the Nusselt numbers depend on the radial temperature distribution of the discs, and the disc temperatures depend on the Nusselt numbers. Furthermore, Coriolis forces in the rotating fluid generate cyclonic and anti-cyclonic circulations inside the cavity. Such flows are three-dimensional, unsteady and unstable, and it is a challenge to compute and measure the heat transfer from the discs to the axial throughflow in the compressor. In this paper, Nusselt numbers are experimentally determined from measurements of steady-state temperatures on the surfaces of both discs in a rotating cavity of the Bath Compressor-Cavity Rig. The data are collected over a range of engine-representative parameters and are the first results from a new experimental facility specifically designed to investigate buoyancy-induced flow. The radial distributions of disc temperature were collected under carefully-controlled thermal boundary conditions appropriate for analysis using a Bayesian model combined with the equations for a circular fin. The Owen-Tang buoyancy model has been used to compare predicted radial distributions of disc temperatures and Nusselt numbers with some of the experimentally determined values, taking account of radiation between the interior surfaces of the cavity. The experiments show that the average Nusselt numbers on the disc increase as the buoyancy forces increase. At high rotational speeds the temperature rise in the core, created by compressibility effects in the air, attenuates the heat transfer and there is a critical rotational Reynolds number for which the Nusselt number is a maximum. In the cavity, there is an inner region dominated by forced convection and an outer region dominated by buoyancy-induced flow. The inner region is a mixing region, in which entrained cold throughflow encounters hot flow from the Ekman layers on the discs. Consequently, the Nusselt numbers on the downstream disc in the inner region tend to be higher than those on the upstream disc.

scholarly journals Wall-Modeled Large-Eddy Simulations of a Multistage High-Pressure Compressor

2019 ◽  
Vol 104 (2-3) ◽  
pp. 725-751 ◽  
Author(s):  
Jerome de Laborderie ◽  
Florent Duchaine ◽  
Laurent Gicquel ◽  
Stephane Moreau
Keyword(s):  
High Pressure ◽  
Large Eddy Simulations ◽  
High Pressure Compressor ◽  
Large Eddy ◽  
Pressure Compressor

Large-Eddy Simulation of an Integrated High-Pressure Compressor and Combustion Chamber of a Typical Turbine Engine Architecture

2020 ◽  
Author(s):  
Carlos Pérez Arroyo ◽  
Jérôme Dombard ◽  
Florent Duchaine ◽  
Laurent Gicquel ◽  
Nicolas Odier ◽  
...  
Keyword(s):  
High Pressure ◽  
Large Eddy Simulation ◽  
Combustion Chamber ◽  
High Amplitude ◽  
Turbine Engine ◽  
Eddy Simulation ◽  
High Pressure Compressor ◽  
Large Eddy ◽  
Pressure Perturbations ◽  
Pressure Compressor

Abstract The design optimization of aviation propulsion systems by means of computational fluid dynamics is key to increase their efficiency and reduce pollutant and noise emissions. The recurrent increase in available computing power allows nowadays to perform unsteady high-fidelity computations of the different components of a gas turbine. However, these simulations are often made independently of each other and they only share average quantities at interfaces. In this work, the methodology and first results for a sectoral large-eddy simulation of an integrated high-pressure compressor and combustion chamber of a typical turbine engine architecture is proposed. In the simulation, the compressor is composed of one main blade and one splitter blade, two radial diffuser vanes and six axial diffuser vanes. The combustion chamber is composed of the contouring casing, the flame-tube and a T-shaped vaporizer. This integrated computation considers a good trade-off between accuracy of the simulation and affordable CPU cost. Results are compared between the stand-alone combustion chamber simulation and the integrated one in terms of global, integral and average quantities. It is shown that pressure perturbations generated by the interaction of the impeller blades with the diffuser vanes are propagated through the axial diffuser and enter the combustion chamber through the dilution holes and the vaporizer. Due to the high amplitude of the pressure perturbations, several variables are perturbed at the blade-passing frequency and multiples. This is also reflected on combustion where two broadband peaks appear for the global heat release.

Large-Eddy Simulation of Buoyancy-Induced Flow in a Sealed Rotating Cavity

2018 ◽  
Author(s):  
Diogo B. Pitz ◽  
John W. Chew ◽  
Olaf Marxen
Keyword(s):  
Large Eddy Simulation ◽  
Boundary Layers ◽  
Flow Structure ◽  
Flow Characteristics ◽  
Global Features ◽  
Eddy Simulation ◽  
Rotating Cavity ◽  
Large Eddy ◽  
Induced Flow ◽  
Buoyancy Induced Flow

Buoyancy-induced flows occur in the rotating cavities of gas turbine internal air systems, and are particularly challenging to model due to their inherent unsteadiness. While the global features of such flows are well documented, detailed analyses of the unsteady structure and turbulent quantities have not been reported. In this work we use a high-order numerical method to perform large-eddy simulation (LES) of buoyancy-induced flow in a sealed rotating cavity with either adiabatic or heated disks. New insight is given into long-standing questions regarding the flow characteristics and nature of the boundary layers. The analyses focus on showing time-averaged quantities, including temperature and velocity fluctuations, as well as on the effect of the centrifugal Rayleigh number on the flow structure. Using velocity and temperature data collected over several revolutions of the system, the shroud and disk boundary layers are analysed in detail. The instantaneous flow structure contains pairs of large, counter-rotating convection rolls, and it is shown that unsteady laminar Ekman boundary layers near the disks are driven by the interior flow structure. The shroud thermal boundary layer scales as approximately Ra−1/3, in agreement with observations for natural convection under gravity.

Large-Eddy Simulation of Buoyancy-Induced Flow in a Sealed Rotating Cavity

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Diogo B. Pitz ◽  
John W. Chew ◽  
Olaf Marxen
Keyword(s):  
Large Eddy Simulation ◽  
Boundary Layers ◽  
Flow Structure ◽  
Flow Characteristics ◽  
Global Features ◽  
Eddy Simulation ◽  
Rotating Cavity ◽  
Large Eddy ◽  
Induced Flow ◽  
Buoyancy Induced Flow

Buoyancy-induced flows occur in the rotating cavities of gas turbine internal air systems, and are particularly challenging to model due to their inherent unsteadiness. While the global features of such flows are well documented, detailed analyses of the unsteady structure and turbulent quantities have not been reported. In this work, we use a high-order numerical method to perform large-Eddy simulation of buoyancy-induced flow in a sealed rotating cavity with either adiabatic or heated disks. New insight is given into long-standing questions regarding the flow characteristics and nature of the boundary layers. The analyses focus on showing time-averaged quantities, including temperature and velocity fluctuations, as well as on the effect of the centrifugal Rayleigh number on the flow structure. Using velocity and temperature data collected over several revolutions of the system, the shroud and disk boundary layers are analyzed in detail. The instantaneous flow structure contains pairs of large, counter-rotating convection rolls, and it is shown that unsteady laminar Ekman boundary layers near the disks are driven by the interior flow structure. The shroud thermal boundary layer scales as approximately Ra−1/3, in agreement with observations for natural convection under gravity.

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