Numerical Study of Spray Parametric Effects on Gas Turbine Combustion Performance

1999 ◽  
Author(s):  
K. Su ◽  
C. Q. Zhou
Keyword(s):  
Temperature Distribution ◽  
Gas Turbine ◽  
Numerical Study ◽  
Combustion Efficiency ◽  
Fuel Spray ◽  
Injection Velocity ◽  
Fuel Sprays ◽  
Combustion Performance ◽  
Mean Diameter ◽  
Spray Distribution

Abstract A numerical study was conducted to determine the effects of fuel spray characteristics on the gas turbine combustion performance including the combustion efficiency and the overall temperature distribution factor (OTDF) at the exit of the combustor using the KIVA-3V code. A model of a typical annular combustor was used in the computations. Operating conditions were varied with inlet pressure from 0.1 to 1.2 MPa, inlet temperature from 400 to 650 K, and air fuel ratio from 0.015 to 0.024. A log-normal spray distribution was assumed to simulate a real fuel spray distribution at injection. The droplet mean diameter as well as injection velocity and angle were independently varied to distinguish the separate effects of variables involved. Flow fields and temperature distributions in the combustor were analyzed. The results reasonably agreed with those from a semi-empirical approach. It is found that the overall temperature distribution deteriorates as the Sauter mean diameter of fuel spray increases. There is an optimum range of the Sauter mean diameters for the efficient combustion of fuel sprays. The overall temperature distribution is improved as the injection velocity of fuel sprays increases, but the combustion efficiency does not change much with it. It appears that the KIVA-3V code can be used to guide the design and improvement of the gas turbine combustor.

Effects of Spray Parameters and Operating Conditions on an Industrial Gas Turbine Washing System

2004 ◽  
Author(s):  
Friederike C. Mund ◽  
Pericles Pilidis
Keyword(s):  
Gas Turbine ◽  
Droplet Size ◽  
Mass Flow ◽  
Gas Turbines ◽  
Numerical Study ◽  
Operating Conditions ◽  
Injection Velocity ◽  
Spray Parameters ◽  
Compressor Inlet ◽  
Spray Distribution

Gas turbines for power generation are exposed to a variety of ambient conditions and are therefore bound to breathe contaminated airflow, thus degrading the engines internal gas path. In particular, accumulated debris on the compressor blades reduces engine efficiency. To recover this performance loss, online compressor washes may be performed. Cleaning fluid is injected through the nozzles upstream of the compressor to wash off the debris from the blades. This paper presents a numerical study of a generic compressor washing system based on an application case for a heavy duty gas turbine power plant. The inlet duct of the engine was modeled and droplet trajectories were calculated. Different spray patterns including single jet and full cone have been investigated for different ranges of injection velocity and droplet size. The spray angle was evaluated experimentally and was used to model the full cone spray pattern. The boundary conditions for the airflow were iterated with a performance simulation tool to match pressure loss and mass flow. To investigate the effect of different operating conditions on the airflow and spray distribution, an installation scenario of the engine at altitude on a hot summer day was modeled. The scenario was based on a review of plant installations and local meteorological conditions. Fluid concentration plots at the compressor inlet plane were evaluated for the different computational cases. Generally with lower injection momentum, the water droplets were significantly deflected by the main airflow. Higher injection velocity and droplet size reduced the effect of the main airflow. Different operating conditions and the significant change of air mass flow affected the spray distribution of the washing system at the compressor inlet. This can be compensated by adjusting the injection angles.

Parametric Studies of Gas Turbine Combustion NOx Emissions Using KIVA With a Reduced Mechanism

2000 ◽  
Author(s):  
K. Su ◽  
C. Q. Zhou
Keyword(s):  
Gas Turbine ◽  
Chemical Mechanism ◽  
Inlet Pressure ◽  
Fuel Spray ◽  
Injection Velocity ◽  
Inlet Temperature ◽  
Nox Emissions ◽  
Wide Range ◽  
Mean Diameter ◽  
Gas Turbine Combustion

Abstract A numerical study was conducted to determine the effects of combustion condition parameters, including inlet temperature and pressure, fuel spray characteristics on NOx emissions in gas turbine combustion using the KIVA-3V code. Log-normal spray distribution was assumed for the simulation of real fuel spray distributions at injection. A simplified mechanism with 17-species and 26-step was employed for chemical reactions of Jet A in a formula of C12H23. A sector model of a typical annular combustor was used in calculations. Flow fields and temperature distributions were analyzed. A wide range of operating condition was varied with the inlet pressure from 0.1 to 2.0 MPa, inlet temperature from 400 to 900 K, and overall fuel/air ratio from 0.012 to 0.08. The results reasonably agreed with those from experimental data and Chemkin modeling, which demonstrates the applicability of KIVA-3V and the chemical mechanism to the predictions of NOx emissions. With respect to the inlet temperature, NOx productions show a trend of monotone increasing. As the inlet pressure increases, NOx emissions increase at the beginning and then decrease. The droplet mean diameter as well as injection velocity and angle were independently varied to distinguish the separate effects of variables involved. It is found that the NOx emissions decrease with the Sauter mean diameter, but increase with the injection velocity and angle of fuel sprays. It appears that KIVA-3V code can be a valuable tool for the development of low emission combustors.

A comparative numerical study of the combustion performance of the syngas-fueled HCCI engine using a toroidal piston, square bowl piston, and flat piston shape at different loads

2021 ◽  
pp. 1-27
Author(s):  
Kabbir Ali ◽  
Changup Kim ◽  
Yonggyu Lee ◽  
Seungmook Oh ◽  
Ki-Seong Kim
Keyword(s):  
Numerical Study ◽  
Pressure Rise ◽  
Fuel Mixture ◽  
Combustion Efficiency ◽  
Maximum Pressure ◽  
Cross Sectional ◽  
Combustion Performance ◽  
Hcci Engine ◽  
Heat Loss Rate ◽  
Piston Bowl

Abstract This study analyzes the combustion performance of a syngas-fueled homogenous charge compression ignition (HCCI) engine using a toroidal piston, square bowl, and flat piston shape, at low, medium, and high loads, with a constant compression ratio of 17.1. In this study, the square bowl shape is optimized by reducing the piston bowl depth and squish area ratio (squish area/cylinder cross-sectional area) from (34 to 20, 10, and 2.5) %, and compared with the flat piston shape and toroidal piston shape. This HCCI engine operates under an overly lean air–fuel mixture condition for power plant usage. ANSYS Forte CFD with GRI Mech3.0 chemical kinetics is used for combustion analysis, and the calculated results are validated by the experimental results. All simulations are accomplished at maximum brake torque (MBT) by altering the air–fuel mixture temperature at IVC with a constant equivalence ratio of 0.27. This study reveals that the main factors that affect the start of combustion , maximum pressure rise rate (MPRR), combustion efficiency, and thermal efficiency by changing the piston shape are the squish flow and reverse squish flow effects. Therefore, the square bowl piston D is the optimized piston shape that offers low MPRR and high combustion performance for the syngas-fueled HCCI engine, due to the weak squish flow and low heat loss rate through the combustion chamber wall, respectively, compared to the other piston shapes of square bowl piston A, B, and C, flat piston, and toroidal (baseline) piston shape.

Liquid Fuel Spray Characterization for the Design of the Dual-Fuel PGT10B Combustor

2001 ◽  
Author(s):  
F. A. Tap ◽  
R. Modi ◽  
J. P. Van Buijtenen
Keyword(s):  
Liquid Film ◽  
Gas Turbine ◽  
Large Scale ◽  
Drop Size ◽  
Numerical Study ◽  
Fuel Spray ◽  
Small Scale ◽  
Dual Fuel ◽  
Test Results ◽  
Liquid Concentration

The Dry Low NOx (DLN) silo combustor of the Nuovo Pignone PGT10B gas turbine is being redesigned to meet Dual-Fuel capability. A prototype with specially designed fuel injectors, placed on airfoil-shaped elements, was tested at cold conditions (using water instead of Diesel fuel) to map the spray mass distribution at the premixer exit. The resulting profile showed high concentrations of liquid near the premixer centerline and on the premixer wall. Parallel to this test, a small-scale experimental and numerical study was made of a single atomizer of the fuel system, placed in cross flow position. This small-scale study was launched in order to gain insight in the behavior of the spray, as well as to assess the relative importance of spray modeling parameters. The PDPA experiments and 2D CFD simulations of these experiments showed fair agreement on the average drop size distribution and drop size-velocity correlation. The flow visualization also revealed liquid film formation on the surface of the airfoil, behind the injector, due to the low atomization pressure differential at cold conditions. Using this modeling experience, the spray patternation test with the prototype combustor has been modeled using an existing 3D CFD model of the premixer. The model also showed high liquid concentration on the wall, but not near the centerline. From the results of the small-scale study it is concluded that the measured high concentration near the premixer centerline is not a result of the flow field. It is assumed that in the complete assembly the liquid film from the injector vanes accumulates on the center body, resulting in a high liquid concentration downstream on the premixer centerline. Overall, the application of CFD analyses on the tests performed proved to be a very useful tool to evaluate the test results. The modeling experience identified the important factors in modeling the fuel spray in a gas turbine environment, but further evolution of computer resources is required before large-scale test results will be reproducible with CFD models.

scholarly journals Numerical Heat Transfer Analysis of an Innovative Gas Turbine Combustor: Coupled Study of Radiation and Cooling in the Upper Part of the Liner

2005 ◽  
Author(s):  
A. Andreini ◽  
A. Bacci ◽  
C. Carcasci ◽  
B. Facchini ◽  
A. Asti ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Gas Turbine ◽  
Cooling System ◽  
Numerical Study ◽  
Radiative Properties ◽  
Heat Transfer Analysis ◽  
Transfer Model ◽  
Cold Side ◽  
Additional Tool

A numerical study of a single can combustor for the GE10 heavy-duty gas turbine, which is being developed at GE-Energy (Oil & Gas), is performed using the STAR-CD CFD package. The topic of the present study is the analysis of the cooling system of the combustor liner’s upper part, named “cap”. The study was developed in three steps, using two different computational models. As first model, the flow field and the temperature distribution inside the chamber were determined by meshing the inner part of the liner. As second model, the impingement cooling system of the cold side of the cap was meshed to evaluate heat transfer distribution. For the reactive calculations, a closure of the BML (Bray-Moss-Libby) approach based on Kolmogorov-Petrovskii-Piskunov theorem was used. The model was implemented in the STAR-CD code using its user coding features. Then the radiative thermal load on the liner walls was evaluated by means of the STAR-CD-native Discrete Transfer model. The selection of the radiative properties of the flame was performed using a correlation procedure involving the total emissivity of the gas, the mean beam length and the gas temperature. The estimated heat flux on the cap was finally used as boundary condition for the calculation of the cooling system, consisting of 68 staggered impingement jet lines on the cold side of the cap. The resulting temperature distribution shows a good agreement with the experimental values measured by thermocouples. The results confirm the validity of the implemented procedure, and point out the importance of a full CFD computation as an additional tool to support classic correlation design procedures.

Effect of Primary Zone Operating Condition for Dilution Mixing Behavior in a Gas Turbine

2015 ◽  
Author(s):  
Wei Dai ◽  
Yuzhen Lin ◽  
Quanhong Xu ◽  
Chi Zhang ◽  
Xin Xue
Keyword(s):  
Temperature Distribution ◽  
Gas Turbine ◽  
Numerical Study ◽  
Experimental Results ◽  
Fuel Particle ◽  
Radial Temperature ◽  
Operating Condition ◽  
Fuel Ratio ◽  
Primary Zone ◽  
Exit Temperature

The exit temperature distribution had a great effect on reliability and security in a gas turbine. In this paper, the exit temperature distribution of a small engine reverse-flow combustor with three injectors test module was experimentally obtained to qualitatively analyze the influence of the primary zone operating condition by changing the fuel air ratio at the ambient pressure and temperature condition. Under the nearly identical air condition, there was no obvious difference on the mixing performance with different fuel flow rate. The hot zones occurred at the same position of the combustor exit section, and the temperature declined in the radial direction from the center. It could be seen that the radial temperature profiles in FAR of 0.022–0.03 were almost same. Malvern experimental results showed that the air fuel ratio of swirler cup ranges from 5 to 40 and the droplet distribution index n could not be increased or decreased by the ratio at different air pressure drop. The air fuel ratio of combustor swirl cup had reached more than 5 which fuel particle had been nearly stable and not got some variation by changing the fuel mass rate. As a result, the increase of fuel air ratio had no impact on fuel atomization uniformity in combustor dome. The fuel had been completely atomized when the combustor fuel air ratio ranged from 0.022 to 0.03, and its impact on the droplet size and uniformity of fuel could be neglected. With the uniform fuel spray, a numerical study of the whole combustor had been made to analyze the strong relation between swirl flow and jets of primary holes and dilution holes. The dilution jets had a strong effect on quenching flame and temperature dilution. Along the combustor flow direction, the temperature difference became less and less obvious, the addition of fuel would enhance the combustion intensity mainly in combustion zone, but with an effect of dilution jet, the temperature distributions had little deviation when increasing the fuel air ratio. And it showed a same phenomenon that different fuel air ratio would make the same exit temperature distribution which was found to be in line with the experimental results. In a word, for the primary zone operating condition in the combustor, it almost had no effect on the temperature distribution at the exit of the combustor by changing the fuel air ratio from 0.022 to 0.030 in primary zone at normal pressure and temperature condition.

scholarly journals Influence of Residence Time on Fuel Spray Sauter Mean Diameter (SMD) and Emissions Using Biodiesel and its Blends in a Low NOx Gas Turbine Combustor

2016 ◽  
Author(s):  
Mohamed A. Altaher ◽  
Hu Li ◽  
Gordon E. Andrews
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Fuel Spray ◽  
Inlet Temperature ◽  
Nox Emissions ◽  
Gaseous Emissions ◽  
Low Carbon ◽  
Sauter Mean Diameter ◽  
Gas Turbine Combustor ◽  
Mean Diameter

Biodiesels have advantages of low carbon footprint, reduced toxic emissions, improved energy supply security and sustainability and therefore attracted attentions in both industrial and aero gas turbines sectors. Industrial gas turbine applications are more practical biodiesels due to low temperature waxing and flow problems at altitude for aero gas turbine applications. This paper investigated the use of biodiesels in a low NOx radial swirler, as used in some industrial low NOx gas turbines. A waste cooking oil derived methyl ester biodiesel (WME) was tested on a radial swirler industrial low NOx gas turbine combustor under atmospheric pressure, 600K air inlet temperature and reference Mach number of 0.017&0.023. The pure WME, its blends with kerosene (B20 and B50) and pure kerosene were tested for gaseous emissions and lean extinction as a function of equivalence ratio for both Mach numbers. Sauter Mean Diameter (SMD) of the fuel spray droplets was calculated. The results showed that the WME and its blends had lower CO, UHC emissions and higher NOx emissions than the kerosene. The weak extinction limits were determined for all fuels and B100 has the lowest value. The higher air velocity (at Mach = 0.023) resulted in smaller SMDs which improved the mixing and atomizing of fuels and thus led to reductions in NOx emissions.

Numerical Study of the Effect of Nozzle Configurations on Characteristics of MILD Combustion for Gas Turbine Application

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
Xiaowen Deng ◽  
Yan Xiong ◽  
Hong Yin ◽  
Qingshui Gao
Keyword(s):  
Gas Turbine ◽  
Numerical Study ◽  
Combustion Efficiency ◽  
Low Noise ◽  
Peak Temperature ◽  
Pollutant Emissions ◽  
Operating Point ◽  
Low Oxygen ◽  
Mild Combustion ◽  
Jet Velocity

The MILD (moderate or intense low-oxygen dilution) combustion is characterized by low emission, stable combustion, and low noise for various kinds of fuel. This paper reports a numerical investigation of the effect of different nozzle configurations, such as nozzle number N, reactants jet velocity V, premixed and nonpremixed modes, on the characteristics of MILD combustion applied to one F class gas turbine combustor. An operating point is selected considering the pressure p = 1.63 MPa, heat intensity Pintensity = 20.5 MW/m3 atm, air preheated temperature Ta = 723 K, equivalence ratio φ = 0.625. Methane (CH4) is adopted as the fuel for combustion. Results show that low-temperature zone shrinks while the peak temperature rises as the nozzle number increases. Higher jet velocity will lead to larger recirculation ratio and the reaction time will be prolonged consequently. It is helpful to keep high combustion efficiency but can increase the NO emission obviously. It is also found that N = 12 and V = 110 m/s may be the best combination of configuration and operating point. The premixed combustion mode will achieve more uniform reaction zone, lower peak temperature, and pollutant emissions compared with the nonpremixed mode.

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