scholarly journals Study of Two-Phase Flow Downstream of a Gas Turbine Combustor Dome Swirl Cup

1993 ◽  
Author(s):  
Anil K. Tolpadi ◽  
David L. Burrus ◽  
Robert J. Lawson
Keyword(s):  
Phase Velocity ◽  
Gas Turbine ◽  
Gas Phase ◽  
Frame Of Reference ◽  
Droplet Velocity ◽  
Computational Domain ◽  
Gas Turbine Combustor ◽  
Two Phase ◽  
Number Count ◽  
Good Agreement

The two-phase axisymmetric flowfield downstream of the swirl cup of an advanced gas turbine combustor is studied numerically. The swirl cup analyzed is that of a single annular GE/SNECMA CFM56 turbofan engine that is comprised of a pair of coaxial counter-swirling air streams together with a fuel atomizer. The atomized fuel mixes with the swirling air stream resulting in the establishment of a complex two-phase flowfield within the swirl chamber. The analysis procedure involves the solution of the gas phase equations in a Eulerian frame of reference. The flow is assumed to be nonreacting and isothermal. The liquid phase is simulated by using a droplet spray model and by treating the motion of the fuel droplets in a Lagrangian frame of reference. Extensive Phase Doppler Particle Analyzer (PDPA) data for the CFM56 engine swirl cup has been obtained at atmospheric pressure by using water as the fuel (Wang et al., 1992a). This includes measurements of the gas phase velocity in the absence and presence of the spray together with the droplet size, droplet number count and droplet velocity distribution information at various axial stations downstream of the injector. Numerical calculations were performed under the exact inlet and boundary conditions as the experimental measurements. The computed gas phase velocity field showed good agreement with the test data. The agreement was found to be best at the stations close to the primary venturi of the swirler and to be reasonable at later stations. To compare the droplet data, a numerical PDPA scheme was formulated whereby several sampling volumes were selected within the computational domain. The trajectories of various droplets passing through these volumes were monitored and appropriately integrated. The calculated droplet count and mean droplet velocity distributions were compared with the measurements and showed very good agreement in the case of larger size droplets and fair agreement for smaller size droplets.

Numerical Computation and Validation of Two-Phase Flow Downstream of a Gas Turbine Combustor Dome Swirl Cup

1995 ◽  
Vol 117 (4) ◽  
pp. 704-712 ◽  
Author(s):  
A. K. Tolpadi ◽  
D. L. Burrus ◽  
R. J. Lawson
Keyword(s):  
Flow Field ◽  
Phase Velocity ◽  
Gas Turbine ◽  
Gas Phase ◽  
Frame Of Reference ◽  
Droplet Velocity ◽  
Phase Flow ◽  
Gas Turbine Combustor ◽  
Two Phase ◽  
Good Agreement

The two-phase axisymmetric flow field downstream of the swirl cup of an advanced gas turbine combustor is studied numerically and validated against experimental Phase-Doppler Particle Analyzer (PDPA) data. The swirl cup analyzed is that of a single annular GE/SNECMA CFM56 turbofan engine that is comprised of a pair of coaxial counterswirling air streams together with a fuel atomizer. The atomized fuel mixes with the swirling air stream, resulting in the establishment of a complex two-phase flow field within the swirl chamber. The analysis procedure involves the solution of the gas phase equations in an Eulerian frame of reference using the code CONCERT. CONCERT has been developed and used extensively in the past and represents a fully elliptic body-fitted computational fluid dynamics code to predict flow fields in practical full-scale combustors. The flow in this study is assumed to be nonreacting and isothermal. The liquid phase is simulated by using a droplet spray model and by treating the motion of the fuel droplets in a Lagrangian frame of reference. Extensive PDPA data for the CFM56 engine swirl cup have been obtained at atmospheric pressure by using water as the fuel (Wang et al., 1992a). The PDPA system makes pointwise measurements that are fundamentally Eulerian. Measurements have been made of the continuous gas phase velocity together with discrete phase attributes such as droplet size, droplet number count, and droplet velocity distribution at various axial stations downstream of the injector. Numerical calculations were performed under the exact inlet and boundary conditions as the experimental measurements. The computed gas phase velocity field showed good agreement with the test data. The agreement was found to be best at the stations close to the primary venturi of the swirler and to be reasonable at later stations. The unique contribution of this work is the formulation of a numerical PDPA scheme for comparing droplet data. The numerical PDPA scheme essentially converts the Lagrangian droplet phase data to the format of the experimental PDPA. Several sampling volumes (bins) were selected within the computational domain. The trajectories of various droplets passing through these volumes were monitored and appropriately integrated to obtain the distribution of the droplet characteristics in space. The calculated droplet count and mean droplet velocity distributions were compared with the measurements and showed very good agreement in the case of larger size droplets and fair agreement for smaller size droplets.

Calculation of Two-Phase Flow in Gas Turbine Combustors

1995 ◽  
Vol 117 (4) ◽  
pp. 695-703 ◽  
Author(s):  
A. K. Tolpadi
Keyword(s):  
Gas Turbine ◽  
Gas Phase ◽  
High Power ◽  
Liquid Droplet ◽  
Frame Of Reference ◽  
Curvilinear Coordinates ◽  
Combustion Model ◽  
Gas Temperature ◽  
Two Phase ◽  
Phase Calculation

A method is presented for computing steady two-phase turbulent combusting flow in a gas turbine combustor. The gas phase equations are solved in an Eulerian frame of reference. The two-phase calculations are performed by using a liquid droplet spray combustion model and treating the motion of the evaporating fuel droplets in a Lagrangian frame of reference. The numerical algorithm employs nonorthogonal curvilinear coordinates, a multigrid iterative solution procedure, the standard k-ε turbulence model, and a combustion model comprising an assumed shape probability density function and the conserved scalar formulation. The trajectory computation of the fuel provides the source terms for all the gas phase equations. This two-phase model was applied to a real piece of combustion hardware in the form of a modern GE/SNECMA single annular CFM56 turbofan engine combustor. For the purposes of comparison, calculations were also performed by treating the fuel as a single gaseous phase. The effect on the solution of two extreme situations of the fuel as a gas and initially as a liquid was examined. The distribution of the velocity field and the conserved scalar within the combustor, as well as the distribution of the temperature field in the reaction zone and in the exhaust, were all predicted with the combustor operating both at high-power and low-power (ground idle) conditions. The calculated exit gas temperature was compared with test rig measurements. Under both low and high-power conditions, the temperature appeared to show an improved agreement with the measured data when the calculations were performed with the spray model as compared to a single-phase calculation.

scholarly journals Scaling of the Two-Phase Flow Downstream of a Gas Turbine Combustor Swirl Cup: Part I—Mean Quantities

1993 ◽  
Vol 115 (3) ◽  
pp. 453-460 ◽  
Author(s):  
H. Y. Wang ◽  
V. G. McDonell ◽  
W. A. Sowa ◽  
G. S. Samuelsen
Keyword(s):  
Gas Turbine ◽  
Droplet Size ◽  
Continuous Phase ◽  
Droplet Velocity ◽  
Scale Model ◽  
Phase Flow ◽  
Gas Turbine Combustor ◽  
Two Phase ◽  
Spatially Resolved ◽  
Phase Doppler Interferometry

A production gas turbine combustor swirl cup and a 3×-scale model (both featuring co-axial, counterswirling air streams) are characterized at atmospheric pressure. Such a study provides an opportunity to assess the effect of scale on the behavior of the continuous phase (gas in the presence of spray) and droplets by comparing the continuous phase velocity, droplet size, and droplet velocity at geometrically analogous positions. Spatially resolved velocity measurements of the continuous phase, droplet size, and droplet velocity were acquired downstream of the production and 3×-scale swirl cups by using two-component phase-Doppler interferometry in the absence of reaction. While the continuous phase flow fields scale well at the exit of the swirl cup, the similarity deviates at downstream locations due to (1) differences in entrainment, and (2) a flow asymmetry in the case of the production hardware. The droplet velocities scale reasonably well with notable exceptions. More significant differences are noted in droplet size, although the presence of the swirl cup assemblies substantially reduces the differences in size that are otherwise produced by the two atomizers when operated independent of the swirl cup.

A Developed Numerical Method for Turbulent Unsteady Fluid Flow in Two-Phase Systems with Moving Interface

2017 ◽  
Vol 14 (06) ◽  
pp. 1750063 ◽  
Author(s):  
A. M. Hegab ◽  
S. A. Gutub ◽  
A. Balabel
Keyword(s):  
Numerical Model ◽  
Gas Phase ◽  
Level Set ◽  
The Body ◽  
Phase System ◽  
Computational Domain ◽  
Two Phase ◽  
Moving Interface ◽  
Level Set Function ◽  
Gas System

This paper presents the development of an accurate and robust numerical modeling of instability of an interface separating two-phase system, such as liquid–gas and/or solid–gas systems. The instability of the interface can be refereed to the buoyancy and capillary effects in liquid–gas system. The governing unsteady Navier–Stokes along with the stress balance and kinematic conditions at the interface are solved separately in each fluid using the finite-volume approach for the liquid–gas system and the Hamilton–Jacobi equation for the solid–gas phase. The developed numerical model represents the surface and the body forces as boundary value conditions on the interface. The adapted approaches enable accurate modeling of fluid flows driven by either body or surface forces. The moving interface is tracked and captured using the level set function that initially defined for both fluids in the computational domain. To asses the developed numerical model and its versatility, a selection of different unsteady test cases including oscillation of a capillary wave, sloshing in a rectangular tank, the broken-dam problem involving different density fluids, simulation of air/water flow, and finally the moving interface between the solid and gas phases of solid rocket propellant combustion were examined. The latter case model allowed for the complete coupling between the gas-phase physics, the condensed-phase physics, and the unsteady nonuniform regression of either liquid or the propellant solid surfaces. The propagation of the unsteady nonplanar regression surface is described, using the Essentially-Non-Oscillatory (ENO) scheme with the aid of the level set strategy. The computational results demonstrate a remarkable capability of the developed numerical model to predict the dynamical characteristics of the liquid–gas and solid–gas flows, which is of great importance in many civilian and military industrial and engineering applications.

Influence of fuel volatility on combustion and emission characteristics in a gas turbine combustor at different inlet pressures and swirl conditions

2002 ◽  
Vol 216 (3) ◽  
pp. 257-268 ◽  
Author(s):  
N. Y. Sharma ◽  
S. K. Som
Keyword(s):  
Gas Turbine ◽  
Gas Phase ◽  
Combustion Efficiency ◽  
Inlet Pressure ◽  
Emission Characteristics ◽  
Spray Parameters ◽  
Gas Turbine Combustor ◽  
Spray Cone ◽  
Emission Level ◽  
Inlet Swirl

The practical challenges in research in the field of gas turbine combustion mainly centre around a clean emission, a low liner wall temperature and a desirable exit temperature distribution for turboma-chinery applications, along with fuel economy of the combustion process. An attempt has been made in the present paper to develop a computational model based on stochastic separated flow analysis of typical diffusion-controlled spray combustion of liquid fuel in a gas turbine combustor to study the influence of fuel volatility at different combustor pressures and inlet swirls on combustion and emission characteristics. A κ-ɛ model with wall function treatment for the near-wall region has been adopted for the solution of conservation equations in gas phase. The initial spray parameters are specified by a suitable probability distribution function (PDF) size distribution and a given spray cone angle. A radiation model for the gas phase, based on the first-order moment method, has been adopted in consideration of the gas phase as a grey absorbing-emitting medium. The formation of thermal NO x as a post-combustion reaction process is determined from the Zeldovich mechanism. It has been recognized from the present work that an increase in fuel volatility increases combustion efficiency only at higher pressures. For a given fuel, an increase in combustor pressure, at a constant inlet temperature, always reduces the combustion efficiency, while the influence of inlet swirl is found to decrease the combustion efficiency only at higher pressure. The influence of inlet pressure on pattern factor is contrasting in nature for fuels with lower and higher volatilities. For a higher-volatility fuel, a reduction in inlet pressure decreases the value of the pattern factor, while the trend is exactly the opposite in the case of fuels with lower volatilities. The NOx emission level increases with decrease in fuel volatility at all combustor pressures and inlet swirls. For a given fuel, the NOx emission level decreases with a reduction in combustor pressure and an increase in inlet swirl number.

OPTICAL MEASUREMENTS OF THE REACTING TWO-PHASE FLOW IN A REALISTIC GAS TURBINE COMBUSTOR AT ELEVATED PRESSURES

2006 ◽  
Vol 16 (5) ◽  
pp. 475-492 ◽  
Author(s):  
Thomas Behrendt ◽  
Martin Carl ◽  
Johannes Heinze ◽  
Christoph Hassa
Keyword(s):  
Gas Turbine ◽  
Two Phase Flow ◽  
Optical Measurements ◽  
Phase Flow ◽  
Gas Turbine Combustor ◽  
Two Phase ◽  
Elevated Pressures

MODELLING WATER ENTRY OF A WEDGE BY MULTIPHASE SPH METHOD

2011 ◽  
Vol 1 (32) ◽  
pp. 10 ◽  
Author(s):  
Kai Gong ◽  
Benlong Wang ◽  
Hua Liu
Keyword(s):  
Water Entry ◽  
Computational Domain ◽  
Two Dimensional ◽  
Hydrodynamic Problem ◽  
Sph Method ◽  
Two Phase ◽  
Boundary Treatment ◽  
Sph Model ◽  
Reflection Boundary ◽  
Good Agreement

The hydrodynamic problem of two-dimensional wedge entering water is studied based on SPH model. A non-reflection boundary treatment for SPH method is proposed to reduce the size of computational domain. The details of water entry and enclosing are simulated using two phase SPH model. Both the water flow around the cavity and wedge and air flow inside the cavity are predicted simultaneity. Good agreement is obtained comparing experimental data in terms of both the hydrodynamics force exerting on the wedge and geometry of the cavity and jet.

scholarly journals Feature-Parameter-Criterion for Predicting Lean Blowout Limit of Gas Turbine Combustor and Bluff Body Burner

2013 ◽  
Vol 2013 ◽  
pp. 1-17 ◽  
Author(s):  
Hongtao Zheng ◽  
Zhibo Zhang ◽  
Yajun Li ◽  
Zhiming Li
Keyword(s):  
Gas Turbine ◽  
Bluff Body ◽  
Flow Distribution ◽  
Gas Turbine Combustor ◽  
Experiment Data ◽  
Lean Blowout ◽  
Feature Parameter ◽  
Computational Fluid Dynamics Cfd ◽  
Mixture Velocity ◽  
Good Agreement

Lean blowout (LBO) limit is one of the most important combustor parameters. A new method named Feature-Parameter-Criterion (FPC) for predicting LBO limit has been put forward in the present work. A computational fluid dynamics (CFD) software FLUENT has been used to simulate the process of LBO of gas turbine combustor and bluff body burner. And “M” flame has been proposed as the portent for predicting lean blowout of gas turbine combustor. Effects of flow velocity, air temperature, droplet averaged-diameter, and flow distribution between swirlers and primary holes on the LBO limit of gas turbine combustor have been researched by use of Feature-Parameter-Criterion in this paper. The effects of fuel air mixture velocity and different structures on bluff body LBO limit have also been analyzed in the present work by use of FPC. The results show that the simulation of LBO limit based on FPC is in good agreement with the experiment data (the errors are about 5%) and this method is reliable for engineering applications.

Energy and Exergy Balance in the Process of Spray Combustion in a Gas Turbine Combustor

2002 ◽  
Vol 124 (5) ◽  
pp. 828-836 ◽  
Author(s):  
S. K. Som ◽  
N. Y. Sharma
Keyword(s):  
Gas Turbine ◽  
Gas Phase ◽  
Transport Processes ◽  
Operating Conditions ◽  
Spray Combustion ◽  
Second Law ◽  
Gas Turbine Combustor ◽  
Thermodynamic Irreversibility ◽  
Entropy Transport ◽  
Exergy Balance

A theoretical model of exergy balance based on availability transfer and flow availability in the process of spray combustion in a gas turbine combustor has been developed to evaluate the total thermodynamic irreversibility and second law efficiency of the process at various operating conditions, for fuels with different volatilities. The velocity, temperature and concentration fields in the combustor, required for the evaluation of the flow availabilities and process irreversibilities, have been computed numerically from a two phase separated flow model of spray combustion. The total thermodynamic irreversibility in the process of spray combustion has been determined from the difference in the flow availability at inlet and outlet of the combustor. The irreversibility caused by the gas phase processes in the combustor has been obtained from the entropy transport equation, while that due to the inter-phase transport processes has been obtained as a difference of gas phase irreversibilities from the total irreversibility. A comparative picture of the variations of combustion efficiency and second law efficiency at different operating conditions for fuels with different volatilities has been made to throw light on the trade off between the effectiveness of combustion and the lost work in the process of spray combustion in a gas turbine combustor.

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