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 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.

Axisymmetric Unsteady Droplet Vaporization and Gas Temperature Distribution

1989 ◽  
Vol 111 (2) ◽  
pp. 487-494 ◽  
Author(s):  
S. K. Lee ◽  
T. J. Chung
Keyword(s):  
Gas Phase ◽  
Gas Temperature ◽  
The Finite Element Method ◽  
Grid Spacing ◽  
Droplet Model ◽  
Time Step ◽  
Two Phase ◽  
Droplet Vaporization ◽  
Droplet Liquid ◽  
Injection Pulse

Droplet vaporization and temperature distributions of axisymmetric unsteady sprays are investigated. The so-called discrete droplet model of two-phase flows, often known as the Eulerian–Lagrangian method, is used. Calculations are carried out with Eulerian coordinates using finite elements for the gas phase and the method of characteristics using the second-order Runge–Kutta scheme for the droplet liquid phase. The sensitivity of the numerical results to changes in time step, injection pulse time, grid spacing, and number of droplet characteristics is examined. Through a simple example, it is shown that applications of the finite element method to more complicated problems appear to be promising.

Investigation on Reaction Flow Field of Low Emission TAPS Combustors

2014 ◽  
Vol 694 ◽  
pp. 45-48
Author(s):  
Qun Zhang ◽  
Hua Sheng Xu ◽  
Tao Gui ◽  
Shun Li Sun ◽  
Yue Wu ◽  
...  
Keyword(s):  
Combustion Process ◽  
Combustion Efficiency ◽  
Combustion Model ◽  
Outlet Temperature ◽  
Gas Temperature ◽  
Distribution Factor ◽  
Two Phase ◽  
Nox Formation ◽  
Low Emission ◽  
Thermal Nox

A twin annular premixing swirler (TAPS) combustor model of low emissions was developed in this study. And computational studies on combustion process in the combustor model were carried out. Standard k-ε Turbulence Model, PDF non-premixed combustion model, Zeldovich thermal NOx formation model and DPM two-phase model were employed. The distributions of some key performance parameters such as gas temperature, flow velocity, concentrations of NOx and CO emissions were obtained and analyzed. At the same time, combustion mechanics inside the TAPS combustor model were investigated. The computational results indicated that the TAPS combustor employed in this study does a better job of improving key combustion performances such as combustion efficiency, total pressure recovery and outlet temperature distribution factor, and reducing NOx and CO emissions at the same time.

scholarly journals Numerical Simulation of a Vortex Combustor Based on Aluminum and Steam

2016 ◽  
Author(s):  
Xianhe Chen ◽  
Zhixun Xia ◽  
Liya Huang ◽  
Likun Ma
Keyword(s):  
Swirling Flow ◽  
Aluminum Particle ◽  
Reynolds Stress Model ◽  
Combustion Model ◽  
Reacting Flow ◽  
Discrete Phase Model ◽  
Aluminum Particles ◽  
Two Phase ◽  
Phase Calculation ◽  
High Efficient

In this paper we report a new development on the numerical model for aluminum-steam combustion. This model is based on diffusion flame of continuum regime and the thermal equilibrium between the particle and the flow field, which can be used to calculate the aluminum particle combustion model for two phase calculation conditions. The model prediction is in good agreement with the experimental data. A new type of vortex combustor was proposed for the combustion of aluminum and steam, and the mathematical model of the two phase reacting flow with in this combustor was established. The turbulence effects are modeled using the Reynolds Stress Model (RSM) with Linear Pressure-Strain approach, and the Eddy-Dissipation model is used to simulate the gas phase combustion. Aluminum particles are injected into the vortex combustor and form a swirling flow around the chamber and their trajectories are traced using the Discrete Phase Model (DPM). The simulation results show that the vortex combustor can achieve high efficient combustion of aluminum and steam. The influencing factors, such as the eccentric distance of the inlet of aluminum particles, particle size and steam inlet diameter, etc., are studied. The work described in this paper represents an attempt to the design of a vortex combustor in order to increase aluminum combustion efficiency.

scholarly journals CFD Liquid Spray Combustion Analysis of a Single Annular Gas Turbine Combustor

1999 ◽  
Author(s):  
Vanco Smiljanovski ◽  
Norbert Brehm
Keyword(s):  
Gas Phase ◽  
Computational Grid ◽  
Combustion Model ◽  
Reacting Flow ◽  
Cfd Analysis ◽  
Fuel Injector ◽  
Lean Burn ◽  
Two Phase ◽  
Radial Temperature ◽  
Liquid Spray

In this paper CFD analysis of the steady two-phase turbulent combusting flow in a single annular low-NOx combustor is presented. For this purpose the commercial code CFD-ACE (1998) was used, where Eulerian equations are solved for the gas phase and the liquid spray fuel droplets are treated in a Lagrangian frame of reference allowing for evaporation of droplets and providing source terms for the gas phase. The standard k-ε model was used for turbulence and an assumed shape probability density function was used for the instantaneous chemistry in the conserved scalar combustion model. Thermal NOx is assumed to be the only source of NOx production and is decoupled from the gas phase reacting flow and calculated in a postprocessing step. The calculation is done on a block structured multi-domain computational grid. Particular attention has be paid to the detailed modeling of the fuel injector having multiple air swirler passages starting from the trailing edge of the air swirler vanes and utilizing up to 400000 computational grid cells for the entire model. The model represents the single annular low-NOx combustor for the BR700 aircraft engine family, which is based on a Rich Burn - Quick Quench - Lean Burn (RQL) concept. CFD analysis is done for high power reduced take off conditions and is compared with full annular rig test results for the temperature traverse and the integral EINOx. The results imply satisfactory prediction capability for the EINOx and the average radial temperature distribution. The prediction of the details of the temperature traverse is not satisfactory and will remain a challenge for the future.

scholarly journals Numerical Predictions of Idle Power Emissions From Gas Turbine Combustors

1993 ◽  
Author(s):  
Timothy G. Valachovic
Keyword(s):  
Gas Turbine ◽  
Test Data ◽  
Reaction Rates ◽  
Curvilinear Coordinates ◽  
Combustion Model ◽  
Idle Power ◽  
Gas Turbine Combustors ◽  
Cooling Flow ◽  
Numerical Predictions ◽  
Flow Changes

Numerical analyses of two existing gas turbine combustors gave predictions of idle power emissions. The calculated exit emissions of unburned hydrocarbons (UHC) and carbon monoxide (CO) are compared to engine test data. For the first combustor, the effects of varying fuel flow on the UHC and CO emissions were investigated while liner cooling flow changes were examined in the second combustor. A fully elliptic three-dimensional computational fluid dynamics code based on pressure correction techniques was employed to model the flow field inside the combustor. Fuel injection was handled using a Lagrangian liquid droplet spray model coupled to the gas phase equations. The combustion model consists of a two-step global reaction mechanism with reaction rates computed using a modified eddy-breakup technique. The numerical algorithm employs non-orthogonal curvilinear coordinates and the standard k-e turbulence model. The results for the first combustor agree well with the test measurements. The baseline result for the second combustor shows good agreement with test data. Predicted effects of cooling flow changes agree with trends from past experience of idle power emissions.

Numerical modeling of the influence of bubbles on flow and heat transfer in the descending gas-liquid flow in a pipe

2012 ◽  
Vol 9 (1) ◽  
pp. 131-135
Author(s):  
M.A. Pakhomov
Keyword(s):  
Heat Transfer ◽  
Gas Phase ◽  
Liquid Flow ◽  
Bubble Diameter ◽  
Gas Content ◽  
Two Phase ◽  
Eulerian Description ◽  
Flow And Heat Transfer ◽  
Gas Liquid Flow ◽  
The Mathematical Model

The paper presents the results of modeling the dynamics of flow, friction and heat transfer in a descending gas-liquid flow in the pipe. The mathematical model is based on the use of the Eulerian description for both phases. The effect of a change in the degree of dispersion of the gas phase at the input, flow rate, initial liquid temperature and its friction and heat transfer rate in a two-phase flow. Addition of the gas phase causes an increase in heat transfer and friction on the wall, and these effects become more noticeable with increasing gas content and bubble diameter.

Numerical investigation of non-uniform flow in twin-silo combustors and impact on axial turbine stage performance

2021 ◽  
pp. 095765092199394
Author(s):  
Hafiz M Hassan ◽  
Adeel Javed ◽  
Asif H Khoja ◽  
Majid Ali ◽  
Muhammad B Sajid
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Internal Flow ◽  
Large Temperature ◽  
Clear Understanding ◽  
Gas Temperature ◽  
Turbine Stage ◽  
Flow Angle ◽  
Axial Turbine ◽  
Stage Performance

A clear understanding of the flow characteristics in the older generation of industrial gas turbines operating with silo combustors is important for potential upgrades. Non-uniformities in the form of circumferential and radial variations in internal flow properties can have a significant impact on the gas turbine stage performance and durability. This paper presents a comprehensive study of the underlying internal flow features involved in the advent of non-uniformities from twin-silo combustors and their propagation through a single axial turbine stage of the Siemens v94.2 industrial gas turbine. Results indicate the formation of strong vortical structures alongside large temperature, pressure, velocity, and flow angle deviations that are mostly located in the top and bottom sections of the turbine stage caused by the excessive flow turning in the upstream tandem silo combustors. A favorable validation of the simulated exhaust gas temperature (EGT) profile is also achieved via comparison with the measured data. A drop in isentropic efficiency and power output equivalent to 2.28% points and 2.1 MW, respectively is observed at baseload compared to an ideal straight hot gas path reference case. Furthermore, the analysis of internal flow topography identifies the underperforming turbine blading due to the upstream non-uniformities. The findings not only have implications for the turbine aerothermodynamic design, but also the combustor layout from a repowering perspective.

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