scholarly journals Numerical study of flame/vortex interactions in 2-D Trapped Vortex Combustor

2014 ◽  
Vol 18 (4) ◽  
pp. 1373-1387 ◽  
Author(s):  
Prasad Mishra ◽  
Renganathan Sudharshan ◽  
Kumar Ezhil
Keyword(s):  
Numerical Study ◽  
Flame Structure ◽  
Reaction Rates ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Base Case ◽  
Primary Vortex ◽  
Vortex Interactions ◽  
Wide Range ◽  
Trapped Vortex

The interactions between flame and vortex in a 2-D Trapped Vortex Combustor are investigated by simulating the Reynolds Averaged Navier Stokes (RANS) equations, for the following five cases namely (i) non-reacting (base) case, (ii) post-vortex ignition without premixing, (iii) post-vortex ignition with premixing, (iv) pre-vortex ignition without premixing and (v) pre-vortex ignition with premixing. For the post-vortex ignition without premixing case, the reactants are mixed well in the cavity resulting in a stable ?C? shaped flame along the vortex edge. Further, there is insignificant change in the vorticity due to chemical reactions. In contrast, for the pre-vortex ignition case (no premixing); the flame gets stabilized at the interface of two counter rotating vortices resulting in reduced reaction rates. There is a noticeable change in the location and size of the primary vortex as compared to case (ii). When the mainstream air is premixed with fuel, there is a further reduction in the reaction rates and thus structure of cavity flame gets altered significantly for case (v). Pilot flame established for cases (ii) and (iii) are well shielded from main flow and hence the flame structure and reaction rates do not change appreciably. Hence, it is expected that cases (ii) and (iii) can perform well over a wide range of operating conditions.

A CFD-Based Parametric Study on Modification of Discrete Sister Holes Location for the Film Cooling Flow

2014 ◽  
Author(s):  
Siavash Khajehhasani ◽  
Bassam Jubran
Keyword(s):  
Film Cooling ◽  
Numerical Study ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Base Case ◽  
Spanwise Direction ◽  
Cooling Performance ◽  
Cooling Flow ◽  
Lift Off ◽  
The Individual

A numerical study on the effects of sister holes locations on film cooling performance is presented. This includes the change of the location of the individual discrete sister holes in the streamwise and spanwise directions, where each one of these directions includes 9 different locations, The simulations are performed using three-dimensional Reynolds-Averaged Navier Stokes analysis with the realizable k–ε model combined with the standard wall function. The variation of the sister holes in the streamwise direction provides similar film cooling performance as the base case for both blowing ratios of 0.5 and 1. On the other hand, the spanwise variation of the sister holes’ location has a more prominent effect on the effectiveness. In some cases, as a result of the anti-vortices generated from the sister holes and the repositioning of the sister holes in the spanwise direction, the jet lift-off effect notably decreases and more volume of coolant is distributed in the spanwise direction.

Detailed Study of Front Module for Low-Emission Combustor

2020 ◽  
Author(s):  
A. Vasilyev ◽  
V. Zakharov ◽  
O. Chelebyan ◽  
O. Zubkova
Keyword(s):  
Experimental Data ◽  
Numerical Study ◽  
Flame Structure ◽  
Combustion Efficiency ◽  
Liquid Fuels ◽  
Pollutant Emission ◽  
Additional Information ◽  
Low Emission ◽  
Wide Range ◽  
To Receive

Abstract At the ASME Turbo Expo 2018 conference held in Oslo (Norway) on the 11th-15th of June 2018, the paper GT2018-75419 «Experience of Low-Emission Combustion of Aviation and Bio Fuels in Individual Flames after Front Mini-Modules of a Combustion Chamber» was published. This paper continues the studies devoted to the low-emission combustion of liquid fuels in GTE combustors. The paper presents a description of more detailed studies of the front module with a staged pneumatic fuel spray. The aerodynamic computations of the front module were conducted, and the disperse characteristics of the fuel-air spray were measured. The experimental research was carried out in two directions: 1) probing of the 3-burner sector flame tube at the distance of one third of its length (temperature field and gas sampling); 2) numerical study of the model combustor with actual arrangement of the modules in the dome within a wide range of fuel-air ratio. The calculated and experimental data of velocity field behind the front module were compared. And new data about the flame structure inside the test sector were obtained. Experimental data confirm the results of preliminary studies of the 3-burner sector: combustion efficiency is higher than 99.8%, EiNOx is at the level of 2–3 g/fuel kg at the combustor inlet air temperature of 680K and fuel-air ratio of 0.0225. The conducted research allowed to receive additional information on the influence of some design units on the pollutant emission and to estimate the different elements of computational methods for simulation of a low-emission combustor with a multi-atomizer dome.

NOx Emissions Reduction in an Innovative Industrial Gas Turbine Combustor (GE10 Machine): A Numerical Study of the Benefits of a New Pilot-System on Flame Structure and Emissions

2005 ◽  
Author(s):  
Antonio Andreini ◽  
Bruno Facchini ◽  
Luca Mangani ◽  
Antonio Asti ◽  
Gianni Ceccherini ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Numerical Study ◽  
Flame Structure ◽  
Combustion Model ◽  
Emissions Reduction ◽  
Minimal Amount ◽  
Nox Emissions ◽  
Ambient Temperatures ◽  
Wide Range

One of the driving requirements in gas turbine design is emissions reduction. In the mature markets (especially the North America), permits to install new gas turbines are granted provided emissions meet more and more restrictive requirements, in a wide range of ambient temperatures and loads. To meet such requirements, design techniques have to take advantage also of the most recent CFD tools. As a successful example of this, this paper reports the results of a reactive 3D numerical study of a single-can combustor for the GE10 machine, recently updated by GE-Energy. This work aims to evaluate the benefits on the flame shape and on NOx emissions of a new pilot-system located on the upper part of the liner. The former GE10 combustor is equipped with fuel-injecting-holes realizing purely diffusive pilot-flames. To reduce NOx emissions from the current 25 ppmvd@15%O2 to less than 15 ppmvd@15%O2 (in the ambient temperature range from −28.9°C to +37.8°C and in the load range from 50% and 100%), the new version of the combustor is equipped with 4 swirler-burners realizing lean-premixed pilot flames; these flames in turn are stabilized by a minimal amount of lean-diffusive sub-pilot-fuel. The overall goal of this new configuration is the reduction of the fraction of fuel burnt in diffusive flames, lowering peak temperatures and therefore NOx emissions. To analyse the new flame structure and to check the emissions reduction, a reactive RANS study was performed using STAR-CD™ package. A user-defined combustion model was used, while to estimate NOx emissions a specific scheme was also developed. Three different ambient temperatures (ISO, −28.9°C and 37.8°C) were simulated. Results were then compared with experimental measurements (taken both from the engine and from the rig), resulting in reasonable agreement. Finally, an additional simulation with an advanced combustion model, based on the laminar flamelet approach, was performed. The model is based on the G-Equation scheme but was modified to study partially premixed flames. A geometric procedure to solve G-Equation was implemented as add-on in STAR-CD™.

Application of an Improved Streamline Curvature Approach to a Modern, Two-Stage Transonic Fan: Comparison With Data and CFD

2002 ◽  
Author(s):  
Keith M. Boyer ◽  
Walter F. O’Brien
Keyword(s):  
Three Dimensional ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Model Parameters ◽  
Two Stage ◽  
Streamline Curvature ◽  
Wide Range ◽  
Improved Model ◽  
Transonic Fan ◽  
Streamline Curvature Method

A streamline curvature method with improvements to key loss models is applied to a two-stage, low aspect ratio, transonic fan with design tip relative Mach number of approximately 1.65. Central to the improvements is the incorporation of a physics-based shock model. The attempt here is to capture the effects of key flow phenomena relative to the off-design performance of the fan. A quantitative analysis regarding solution sensitivities to model parameters that influence the key phenomena over a wide range of operating conditions is presented. Predictions are compared to performance determined from overall and interstage measurements, as well as from a three-dimensional, steady, Reynolds-averaged Navier-Stokes method applied across the first rotor. Overall and spanwise comparisons demonstrate that the improved model gives reasonable performance trending and generally accurate results. The method can be used to provide boundary conditions to higher-order solvers, or implemented within novel approaches using the streamline curvature method to explore complex engine-inlet integration issues, such as time-variant distortion.

Hydrodynamics of Podded Propulsors With Highly Loaded Propellers and in Extreme Azimuthing Conditions

2015 ◽  
Author(s):  
Mohammed Islam ◽  
Fatima Jahra ◽  
Ron Ryan ◽  
Lee Hedd
Keyword(s):  
Numerical Study ◽  
Open Water ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Hydrodynamic Characteristics ◽  
Podded Propulsor ◽  
Order Of Magnitude ◽  
Thrust And Torque ◽  
Straight Ahead ◽  
Highly Loaded

State of the art CFD capabilities has enabled the accurate prediction of forces and moments on the propeller as well as on the pod-strut body due to small to moderate azimuthing angles. The capability of CFD to predict the hydrodynamics at extreme azimuthing angles is yet to be demonstrated. The aim of this research is to develop a simulation capability to capture most of the dynamics of podded propulsion systems in regular to extreme operating conditions. The numerical methodologies to evaluate the hydrodynamic characteristics of podded propulsors in puller configurations in extremely oblique inflow and highly loaded condition in open water and the associated results are presented in this paper. A numerical study is carried out to predict the hydrodynamic forces of a podded propulsor unit in various extreme static azimuthing conditions. An unsteady Reynolds-Averaged Navier Stokes (RANS) solver is used to predict the propulsive performance of the podded propulsor system in puller configuration using both steady and unsteady state solutions. To obtain insight into the reliability and accuracy of the results, grid dependency studies are conducted for a podded propulsor in straight-ahead condition. RANS solver simulation technique is first validated against measurements of a puller podded propulsor in straight ahead condition for multiple loading scenarios. The propeller thrust and torque as well as the forces and moments of the pod unit in the three coordinate directions in straight-ahead condition and at static azimuthing angles in the range of −180° to 180° at advance coefficient of 0.20 are then compared with that of the measurements. Additionally, the velocity and pressure distribution on and around the pod-strut-propeller bodies are presented as derived from the RANS predictions. Analysis demonstrates that the RANS solver can predict the performance coefficients of the podded propulsor in extreme azimuthing and in the highly loaded conditions within the same level of accuracy of the same order of magnitude of the experimental results.

Simulation of Fluid Flow Through a Granular Bed

2006 ◽  
Author(s):  
Arezou Jafari ◽  
S. Mohammad Mousavi
Keyword(s):  
Stokes Equations ◽  
Numerical Study ◽  
Fluid Velocity ◽  
Three Dimensional ◽  
Packed Bed ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Wide Range ◽  
Duct Geometry ◽  
Flow Through

Numerical study of flow through random packing of non-overlapping spheres in a cylindrical geometry is investigated. Dimensionless pressure drop has been studied for a fluid through the porous media at moderate Reynolds numbers (based on pore permeability and interstitial fluid velocity), and numerical solution of Navier-Stokes equations in three dimensional porous packed bed illustrated in excellent agreement with those reported by Macdonald [1979] in the range of Reynolds number studied. The results compare to the previous work (Soleymani et al., 2002) show more accurate conclusion because the problem of channeling in a duct geometry. By injection of solute into the system, the dispersivity over a wide range of flow rate has been investigated. It is shown that the lateral fluid dispersion coefficients can be calculated by comparing the concentration profiles of solute obtained by numerical simulations and those derived analytically by solving the macroscopic dispersion equation for the present geometry.

Viscous Flow Analysis in Mixed Flow Rotors

1980 ◽  
Vol 102 (1) ◽  
pp. 193-201 ◽  
Author(s):  
I. Khalil ◽  
W. Tabakoff ◽  
A. Hamed
Keyword(s):  
Viscous Flow ◽  
Stokes Equations ◽  
Flow Analysis ◽  
Flow Characteristics ◽  
Laminar Flows ◽  
Operating Conditions ◽  
Field Analysis ◽  
Navier Stokes ◽  
Stream Channels ◽  
Wide Range

A method for analyzing the viscous flow through turbomachine rotors is presented. The field analysis is based on the solution of the full Navier-Stokes equations over the rotor blade-to-blade stream channels. An Alternating-Direction-Implicit method is employed to carry out the necessary numerical integration of the elliptic governing equations. The flow analysis may be applied to various types of turbomachine rotors. Preliminarily, only the case of laminar flows are considered in this paper. The flow characteristics within the rotors of a radial inflow turbine and a radial bladed compressor are investigated over a wide range of operating conditions. Excellent results are obtained when compared with existing experimental data. The method of this analysis is quite general and can deal with wide range of applications. Possible modification of the present study to deal with turbulent flow cases are also identified.

Analytical Maps of Aerodynamic Damping as a Function of Operating Condition for a Compressor Profile

2006 ◽  
Author(s):  
Paul J. Petrie-Repar ◽  
Andrew McGhee ◽  
Peter A. Jacobs ◽  
Rowan Gollan
Keyword(s):  
Inviscid Flow ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Compressor Cascade ◽  
Operating Condition ◽  
Flow Solver ◽  
Aerodynamic Damping ◽  
Wide Range ◽  
Contour Plots ◽  
Standard Configuration

In this paper, analytical maps of aerodynamic damping for a two-dimensional compressor cascade (Standard Configuration 10) are presented. The maps are shown as contour plots of the aerodynamic damping as a function of operating condition. The aerodynamic dampings were calculated by a linearized Navier-Stokes flow solver. The flutter boundaries over a wide range of operating conditions are clearly shown on the damping maps and were found to be strongly dependent on the mode frequency and the mode shape. Extremely low values of negative aerodynamic damping were predicted for some off-design operating conditions where flow separation occurred. A damping map was also constructed based on inviscid flow simulations. There were differences in the viscous and inviscid flutter boundaries particularly at off-design inflow angles. The extremely low values of negative aerodynamic damping were only predicted by the viscous simulations and not the inviscid simulations.

scholarly journals Meander-Like Shape Optimization of the Stator-Rotor Platform Cavity

2018 ◽  
Author(s):  
Paht Juangphanich ◽  
Guillermo Paniagua
Keyword(s):  
Geometry Optimization ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Practical Implementation ◽  
Computational Domain ◽  
Optimization Strategy ◽  
Minimum Thickness ◽  
Ansys Fluent ◽  
Driving Mechanisms ◽  
Wide Range

Recent progress in additive manufacturing has enabled opportunities to explore novel stator rim geometries which can be implemented to improve cooling strategies in turbomachinery. This paper presents a simplified stationary geometry optimization strategy to produce enhanced stator-rotor cavity sealing and highlights main driving mechanisms. The stator and rotor rims were designed using a design strategy based on inspiration from the meandering of rivers. A minimum thickness of 2mm was maintained throughout the cavity to ensure a practical implementation. The computational domain comprised of the stator outlet, hub disk leakage cavity, and rotor platform was meshed using NUMECA Int. package, Hexpress. The numerical analysis required 3D Unsteady Reynolds Average Navier-Stokes to replicate vorticial structures using Ansys Fluent. The operating conditions were representative of engine-like conditions, exploring a wide range of massflow ratios from 1 to 3%. The optimization yielded designs that provide 30% reduction in rear platform temperature while minimizing coolant massflow. The applicability of the design was compared against 3D sector in both stationary and in rotation.

Experimental and Numerical Investigation of the Flow in a Low-Pressure Industrial Steam Turbine With Part-Span Connectors

2016 ◽  
Vol 138 (7) ◽  
Author(s):  
Markus Häfele ◽  
Christoph Traxinger ◽  
Marius Grübel ◽  
Markus Schatz ◽  
Damian M. Vogt ◽  
...  
Keyword(s):  
Flow Field ◽  
Steam Turbine ◽  
Numerical Study ◽  
Three Dimensional ◽  
Low Pressure ◽  
Operating Conditions ◽  
Engineering Practice ◽  
Cfd Model ◽  
Wide Range ◽  
The Impact

An experimental and numerical study on the flow in a three-stage low-pressure (LP) industrial steam turbine is presented and analyzed. The investigated LP section features conical friction bolts in the last and a lacing wire in the penultimate rotor blade row. These part-span connectors (PSC) allow safe turbine operation over an extremely wide range and even in blade resonance condition. However, additional losses are generated which affect the performance of the turbine. In order to capture the impact of PSCs on the flow field, extensive measurements with pneumatic multihole probes in an industrial steam turbine test rig have been carried out. State-of-the-art three-dimensional computational fluid dynamics (CFD) applying a nonequilibrium steam (NES) model is used to examine the aerothermodynamic effects of PSCs on the wet steam flow. The vortex system in coupled LP steam turbine rotor blading is discussed in this paper. In order to validate the CFD model, a detailed comparison between measurement data and steady-state CFD results is performed for several operating conditions. The investigation shows that the applied one-passage CFD model is able to capture the three-dimensional flow field in LP steam turbine blading with PSC and the total pressure reduction due to the PSC with a generally good agreement to measured values and is therefore sufficient for engineering practice.

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