Computational assessment of performance parameters of an aero gas turbine combustor for full flight envelope operation

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Saroj Kumar Muduli ◽  
R. K. Mishra ◽  
Purna Chandra Mishra
Keyword(s):  
Gas Turbine ◽  
Cone Angle ◽  
Performance Estimation ◽  
Temperature Pattern ◽  
Operating Pressure ◽  
Performance Parameters ◽  
Gas Turbine Combustor ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Wide Range

Abstract This paper presents the computational study carried out on an aero gas turbine combustor to assess important performance parameters. The CFD results are compared with experimental dataobtained from the full scale combustor tested at ground test stand simulating various operational conditions. The CFD predictions have agreed very well with the experimental data. The model is then extended to predict combustor exit temperature pattern factors, pressure loss, and combustion efficiency and exhaust gas constituents over a wide range of operating pressure and temperature conditions. The paper also presents the studies carried out on the effect of atomizer spray cone angle, particle size and fuel flow variations expected due to manufacturing tolerances in various flow passages as well as due to operational degradations on temperature pattern factors. The pattern factors are also analyzed on cold and hot day environment. The radial pattern factor (RPF) at mid height is found to increase as altitude increases from sea level to 12 km. Spray cone angle is found to have a predominant effect on temperature non-uniformity at exit, lower cone angle increasing both radial and circumferential pattern factors. The findings of this study are valuable inputs for engine performance estimation.

Experimental and Numerical Studies of Diesel Spray Evaporation and Combustion in a Gas Turbine Matrix Burner

2009 ◽  
Author(s):  
Dieter Bohn ◽  
James F. Willie ◽  
Nils Ohlendorf
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Combustion Instability ◽  
Cone Angle ◽  
Spray Angle ◽  
Test Rig ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Flow Simulations ◽  
Air Inlet

Lean gas turbine combustion instability and control is currently a subject of interest for many researchers. The motivation for running gas turbines lean is to reduce NOx emissions. For this reason gas turbine combustors are being design using the Lean Premixed Prevaporized (LPP) concept. In this concept, the liquid fuel must first be atomized, vaporized and thoroughly premixed with the oxidizer before it enters the combustion chamber. One problem that is associated with running gas turbines lean and premixed is that they are prone to combustion instability. The matrix burner test rig at the Institute of Steam and Gas Turbines at the RWTH Aachen University is no exception. This matrix burner is suitable for simulating the conditions prevailing in stationary gas turbines. Till now this burner could handle only gaseous fuel injection. It is important for gas turbines in operation to be able to handle both gaseous and liquid fuels though. This paper reports the modification of this test rig in order for it to be able to handle both gaseous and liquid primary fuels. Many design issues like the number and position of injectors, the spray angle, nozzle type, droplet size distribution, etc. were considered. Starting with the determination of the spray cone angle from measurements, CFD was used in the initial design to determine the optimum position and number of injectors from cold flow simulations. This was followed by hot flow simulations to determine the dynamic behavior of the flame first without any forcing at the air inlet and with forcing at the air inlet. The effect of the forcing on the atomization is determined and discussed.

scholarly journals Dynamic Response of Fuel Nozzles for Liquid-Fueled Gas Turbine Combustors

1996 ◽  
Author(s):  
Mounir Ibrahim ◽  
Terry Sanders ◽  
Douglas Darling ◽  
Michelle Zaller
Keyword(s):  
Gas Turbine ◽  
Cone Angle ◽  
Outer Region ◽  
Test Fluid ◽  
Mean Flow ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Gas Turbine Combustors ◽  
The Mean ◽  
Piezoelectric Drive

To imitate resonances that might occur in the fuel delivery system of gas turbine combustors, the incoming liquid streams of two pressure swirl nozzles were perturbed using a piezoelectric driver. Frequencies of perturbations examined were from 3 to 20 kHz, and water was used as the test fluid. A video camera and a Phase Doppler Particle Analyzer (PDPA) were used to study the effect of perturbations on the mean flow quantities of the sprays. Various lighting arrangements were used for the video photography: back lighting, front lighting, a strobe synchronized with the input to the piezoelectric, and a laser sheet oriented along the midplane of the sprays. The study showed that the piezoelectric drive had an effect an the spray system at discrete frequencies. At these particular frequencies, by increasing the input voltage, it was found that the piezoelectric drive affected the atomization in the following ways: (1) the mean flow rate decreased, (2) the spray cone angle decreased, (3) the break up length decreased, (4) the peak of the spatial distribution of the mean droplet size decreased, and (5) the mean droplet sizes and velocities increased near the spray center line and decreased in the outer region of the spray. A hysteresis effect of the drive frequency on the spray cone angle was observed. The results indicated that more fundamental research is needed to gain an in-depth understanding of the physical processes induced in the spray by the piezoelectric drive.

scholarly journals Calculation of flow characteristics of liquid fuel supplied through pressure jet atomizers of small-sized gas turbine engines

2021 ◽  
Vol 20 (2) ◽  
pp. 19-35
Author(s):  
N. I. Gurakov ◽  
I. A. Zubrilin ◽  
M. Hernandez Morales ◽  
D. V. Yakushkin ◽  
A. A. Didenko ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Liquid Fuel ◽  
Cone Angle ◽  
Flow Characteristics ◽  
Design Parameters ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Semi Empirical

The paper presents the results of studying the flow characteristics of liquid fuel in pressure jet atomizers of small-sized gas turbine engines with nozzle diameters of 0.4-0.6 mm for various operating and design parameters. The study was carried out using experimental measurements, semi-empirical correlations and CFD (computational fluid dynamics) methods. The Euler approach, the volume- of- fluid (VOF) method, was used to model multiphase flows in CFD simulations. Good agreement was obtained between experimental and predicted data on the fuel coefficient and the primary spray cone angle at the nozzle outlet. Besides, the assessment of the applicability of semi-empirical techniques for the nozzle configurations under consideration is given. In the future, the flow characteristics in question (the nozzle flow rate, the fuel film thickness, and the primary spray cone angle) can be used to determine the mean diameter of the droplets (SMD) required to fully determine the boundary conditions of fuel injection when modeling combustion processes in combustion chambers of small-sized gas turbine engines.

Effect of Injection Rate Shaping Over Diesel Spray Development in Non Reacting Evaporative Conditions

2012 ◽  
Author(s):  
Raul Payri ◽  
Jaime Gimeno ◽  
Michele Bardi ◽  
Alejandro Plazas
Keyword(s):  
Fuel Injection ◽  
Cone Angle ◽  
Injection Rate ◽  
Effective Diameter ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Test Conditions ◽  
Needle Position ◽  
Rate Shaping ◽  
Wide Range

A prototype Diesel common rail direct-acting piezoelectric injector has been used to study the influence of fuel injection rate shaping on spray behavior (liquid phase penetration) under evaporative and non-reacting conditions. This state of the art injector allows a fully flexible control of the nozzle needle, enabling various fuel injection rates typologies under a wide range of test conditions. The tests have been performed employing a novel continuous flow test chamber that allows an accurate control on a wide range of thermodynamic test conditions (up to 1000 K and 15 MPa). The temporal evolution of the spray has been studied recording movies of the injection event with a fast camera (25 kfps) by means of the Mie scattering visualization technique. The analysis of the results showed a strong influence of needle position on the behavior of the liquid length. The needle position controls the effective pressure upstream of the nozzle holes. Higher needle lift is equivalent to higher effective pressures. According to the free-jet theory, the stabilized liquid-length depends mainly on effective diameter, spray cone-angle and fuel/air properties and does not depend on injection velocity. Therefore, higher injection pressures gives slightly lower liquid length due to small change in the spray cone-angle. However, partial needle lifts has an opposite effect: lower effective pressure upstream of the nozzle holes shows a dramatic increase on the spray cone-angle, reducing the liquid length. This behavior could be explained mainly due to the fact that the flow direction upstream of the nozzle holes is affecting the area coefficient, or in other words, the effective diameter of the holes.

scholarly journals Research on the internal flow and macroscopic characteristics of a diesel fuel injection process

PLoS ONE ◽  
2021 ◽  
Vol 16 (9) ◽  
pp. e0255874
Author(s):  
Hua Xia
Keyword(s):  
Fuel Injection ◽  
Cone Angle ◽  
Injection Pressure ◽  
Internal Flow ◽  
Spray Angle ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Injection Process ◽  
Wide Range ◽  
Diesel Fuel Injection

The internal flow and macroscopic spray behaviors of a fuel injection process were studied with schlieren spray techniques and simulations. The injection pressures(Pin)and ambient pressures(Pout)were applied in a wide range. The results showed that increasing the Pin is likely to decrease the flow performance of the nozzle. Furthermore, increasing the Pin can increase the spray tip penetration. However, the effect of Pin on the spray cone angle was not evident. The spray cone angle at an injection pressure of 160MPa was 21.7% greater than at a pressure of 100MPa during the initial spraying stage. Additionally, the discharge coefficient increased under high Pout, and the decrease in Pout can promote the formation of cavitation. Finally, increasing the Pout can decrease the penetration, while the spray angle becomes wider, especially at the initial spray stage, and high Pout will enhance the interaction of the spray and the air, which can enhance the spray quality.

Effect of Spray Cone Angle on Flame Stability in an Annular Gas Turbine Combustor

2016 ◽  
Vol 33 (1) ◽  
Author(s):  
R. K. Mishra ◽  
S. Kishore Kumar ◽  
Sunil Chandel
Keyword(s):  
Cone Angle ◽  
Full Scale ◽  
Experimental Result ◽  
Test Facility ◽  
Flame Stability ◽  
Operating Pressure ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Lean Blowout ◽  
Annular Combustor

AbstractEffect of fuel spray cone angle in an aerogas turbine combustor has been studied using computational fluid dynamics (CFD) and full-scale combustor testing. For CFD analysis, a 22.5° sector of an annular combustor is modeled and the governing equations are solved using the eddy dissipation combustion model in ANSYS CFX computational package. The analysis has been carried out at 125 kPa and 303 K inlet conditions for spray cone angles from 60° to 140°. The lean blowout limits are established by studying the behavior of combustion zone during transient engine operation from an initial steady-state condition. The computational study has been followed by testing the practical full-scale annular combustor in an aerothermal test facility. The experimental result is in a good agreement with the computational predictions. The lean blowout fuel–air ratio increases as the spray cone angle is decreased at constant operating pressure and temperature. At higher spray cone angle, the flame and high-temperature zone moves upstream close to atomizer face and a uniform flame is sustained over a wide region causing better flame stability.

Soot Formation and Its Effect in an Aero Gas Turbine Combustor

2019 ◽  
Vol 36 (1) ◽  
pp. 61-73 ◽  
Author(s):  
R. K. Mishra ◽  
Sunil Chandel
Keyword(s):  
Gas Turbine ◽  
Equivalence Ratio ◽  
Soot Formation ◽  
Cone Angle ◽  
Peak Temperature ◽  
Soot Concentration ◽  
Gas Turbine Combustor ◽  
Spray Cone ◽  
Primary Zone ◽  
Soot Deposit

Abstract Soot formation and the effect of soot deposit on the performance and integrity on an aero gas turbine combustor has been studied. Defective atomizer or blockage of air passages creates a fuel rich mixture which promotes soot formation in combustor primary zone. The temperature field and soot concentration inside the liner has been analyzed at high equivalence ratio using computational model in CFX. The peak temperature in primary zone increases till equivalence ratio reaches ϕ=1.1. But at high equivalence ratio, i. e., ϕ≥1.2, the peak temperature in primary zone decreases and that in dilution zone increases. Soot concentration increases at liner front end as well as in dilution zone when equivalence ratio increases from 1.25 to 3.0. Erosion and distortion of atomizer flow passages cause higher spray cone angle which again increases the soot concentration. Soot deposit inside liner has detrimental effect on the life and performance of the combustor as well as of the aero engine.

Assessment of Exit Temperature Pattern Factors in an Annular Gas Turbine Combustor: An Overview

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
S. K. Muduli ◽  
R. K. Mishra ◽  
P. C. Mishra
Keyword(s):  
Gas Turbine ◽  
Turbine Blades ◽  
Engine Performance ◽  
Turbine Engines ◽  
Geometrical Parameters ◽  
Temperature Pattern ◽  
Gas Turbine Combustor ◽  
Combat Aircraft ◽  
Wide Range ◽  
Exit Temperature

Abstract The present paper overviews the works carried out on achieving desired temperature pattern factors at combustor exit in gas turbine engines. These pattern factors are very important from the point of engine performance and life of turbine blades and vanes. They are controlled by a number of geometrical parameters such as liner front-end air passages, primary air holes, atomizer characteristics and air swirl number and dilution zone geometrical configuration. Combustor inlet pressure, Mach number, velocity profile and fuel-air ratio are the major operating parameters that influence the pattern factors. Due to the design uniqueness and importance of pattern factors, it is always a challenge to assess the pattern factors over a wide range of mission points for a gas turbine combustor designed for combat aircraft.

Gas Turbine Inlet Air Cooling: Determination of Parameters to Evaluate Fogging Nozzle’s Atomizing Performance

2003 ◽  
Author(s):  
Sanjay Mahapatra ◽  
Jeffrey K. Gilstrap
Keyword(s):  
Gas Turbine ◽  
Surface Area ◽  
Drop Size ◽  
Cone Angle ◽  
Air Cooling ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Droplet Distribution ◽  
Turbine Inlet ◽  
Air Stream

Gas turbine inlet air-cooling using a fogging system is accomplished by using an array of high-pressure nozzles that inject micron-sized droplets in air stream. These droplets evaporate and diffuse in the air stream resulting in cooling and humidification of air. The cooled and moist inlet air increases net turbine power output, improves heat rate and reduces Nitrogen Oxides formation (NOx). The evaporation and mass diffusion of these droplets are influenced, among other factors, by its surface area to volume ratio. Large surface area facilitates drop interfacial heat transfer and smaller volume or weight aids higher droplet residence times. A fogging nozzle’s atomizing performance can be evaluated from its spray properties that include a mean drop size, droplet distribution, numerical droplet density, spray cone angle, and spray penetration. The spray industry adopts various definitions of mean drop size that suits its application and objective. Mean drop sizes or more commonly droplet diameters used in the gas turbine inlet air fogging industry are 90% cumulative volume frequency, Dv0.90 and the Sauter Mean Diameter, D32. Two sprays having identical mean or representative diameter are not necessarily similar in performance. Further, a spray from nozzle ‘A’ having a Dv0.90 less than another nozzle ‘B’ does not necessarily imply that ‘A’ is superior to ‘B’. This paper explains why the use of one or both of the above characteristic diameters does not effectively reflect a fog nozzle’ atomizing performance. This paper also analyzes various characteristic diameters and their relevance to evaporative cooling using fog nozzles. In fogging applications, the smallest and/or the largest sized drops in a spray will have significant impact on performance and neither Dv0.90 nor D32 can independently provide this information. Therefore, at least one other parameter such as the droplet distribution must be known in order to qualitatively define a spray from a fogging nozzle. This paper also determines these parameters such as the Relative Span Factor and Dispersion Boundary Factor and analyzes their importance to fogging performance.

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