CFD Analysis of the Combustion Chamber of a Commercial Aircraft Engine of Medium Thrust Class From a Maintenance Perspective

2017 ◽  
Author(s):  
Stefan Kuntzagk ◽  
Jörn Kraft ◽  
Ina Esemann
Keyword(s):  
Combustion Chamber ◽  
Temperature Profile ◽  
Measurement Errors ◽  
Burning Velocity ◽  
Combustion Model ◽  
Cfd Analysis ◽  
Hexahedral Mesh ◽  
Flow Topology ◽  
Geometrical Features ◽  
Exit Temperature

The combustion chamber of aircraft engines plays an important role in achieving the optimum performance during an engine overhaul. For long decades, it has been common understanding in the MRO business that a well overhauled compressor and turbine are required to get an engine with low SFC and high EGT margin. In recent work at Lufthansa Technik AG, a comprehensive CFD analysis of the combustion chamber showed that, in contrast to this, small geometrical features influence the mixing process in the combustion chamber and can have an effect on the exit temperature profile. This in turn can reduce the accuracy of the EGT measurement significantly and create measurement errors and misinterpretations of the real engine performance. In order to get insight into the flow topology, a very detailed digital model has been created using scans of the hardware available in the shop. Important geometrical features such as the cooling provisions and swirl creating components have been included in a very detailed manner with an efficient hexahedral mesh. The model includes the HPT vanes and the cooling flow extraction from the secondary cold flow. CFD results have been generated using the flow solver Ansys CFX 17.1, which is able to predict all relevant physical effects such as injection of liquid fuel, evaporation, and combustion of Jet A1 fuel using the Burning-Velocity combustion model. The flow in the combustion chamber shows large natural fluctuations. Subsequently, for each case a transient calculation has been carried out in order to allow an evaluation of the time-averaged flow field. Different geometrical features are investigated to predict the effect of geometry deviations on the exit temperature profile, e.g. the shape and size of the dilution holes. Finally along the example of two CFM56 engines it will be shown how the data obtained by the detailed CFD model is used to optimize work-scoping and maintenance procedures. On the two cases put forward the combination of extended test-cell instrumentation and detailed modeling enabled not only the identification but also the rectification of combustion chamber deviations. This in turn minimized the necessary work, whereas in the past combustion chamber issues often went unnoticed and consequently resulted in extensive additional work.

Effects of Combustion Chamber Geometry Deviations Upon Exit Temperature Profiles for Populations With Varied Service Limitations

2011 ◽  
Vol 133 (11) ◽  
Author(s):  
Clayton Kotzer ◽  
Marc LaViolette ◽  
William Allan ◽  
Asad Asghar
Keyword(s):  
Combustion Chamber ◽  
Temperature Profile ◽  
Laser Scanning ◽  
Reference Model ◽  
Ambient Pressure ◽  
Three Dimensional ◽  
Temperature Fields ◽  
Scanning System ◽  
Geometric Deviations ◽  
Exit Temperature

The purpose of this continuing research was to investigate the effects of combustion chamber geometry on exit temperature fields using a validated ambient pressure test rig. Rig test conditions were set to simulate an engine operating condition of 463 km/h (250 kn) at 7620 m (25,000 ft) by matching Mach number, equivalence ratio, and Sauter mean diameter of the fuel spray. Using a thermocouple rake, high resolution temperature measurements were obtained in the combustion chamber exit plane. Following the previously published procedures, a three-dimensional laser scanning system was used to quantify geometric deviations from two populations of combustion chambers. These populations differed in that one had a significantly higher allowable engine operating temperature for continuous cruise condition. Geometric deviations of both populations were compared with the reference model. The relationship between combustion chamber exit temperature profile and geometric deviation of each population was then compared. The main conclusion of this research was that the temperature profile degradation of both populations due to geometric deviations followed similar trends. These results highlighted that the difference in operating limitations of these populations did not significantly affect component performance.

Effects of Combustion Chamber Geometry Deviations Upon Exit Temperature Profiles for Populations With Varied Service Limitations

2010 ◽  
Author(s):  
Clayton Kotzer ◽  
Marc LaViolette ◽  
William Allan ◽  
Asad Asghar
Keyword(s):  
Combustion Chamber ◽  
Temperature Profile ◽  
Laser Scanning ◽  
Reference Model ◽  
Ambient Pressure ◽  
Three Dimensional ◽  
Temperature Fields ◽  
Scanning System ◽  
Geometric Deviations ◽  
Exit Temperature

The purpose of this continuing research was to investigate the effects of combustion chamber geometry on exit temperature fields using a validated ambient pressure test rig. Rig test conditions were set to simulate an engine operating condition of 463 km/h (250 knots) at 7 620 m (25,000 ft) by matching Mach number, equivalence ratio and Sauter mean diameter of the fuel spray. Using a thermocouple rake, high resolution temperature measurements were obtained in the combustion chamber exit plane. Following the previously published procedures, a three-dimensional laser scanning system was used to quantify geometric deviations from two populations of combustion chambers. These populations differed in that one had a significantly higher allowable engine operating temperature for continuous cruise condition. Geometric deviations of both populations were compared to the reference model. The relationship between combustion chamber exit temperature profile and geometric deviation of each population was then compared. The main conclusion of this research was that the temperature profile degradation of both populations due to geometric deviations followed similar trends. These results highlighted that the difference in operating limitations of these populations did not significantly affect component performance.

scholarly journals Laminar burning velocity of ethanol premixed combustion enriched with liquefied petroleum gas (LPG)

Energetika ◽  
2017 ◽  
Vol 63 (1) ◽  
Author(s):  
Muh Nurkoyim Kustanto ◽  
I Nyoman Gede Wardana ◽  
Mega Nur Sasongko ◽  
Lilis Yuliati
Keyword(s):  
Combustion Chamber ◽  
Burning Velocity ◽  
Premixed Combustion ◽  
Combustion Model ◽  
Oh Radicals ◽  
Laminar Burning Velocity ◽  
Liquefied Petroleum Gas ◽  
Pure Ethanol

The laminar burning velocity of ethanol premixed combustion enriched with liquefied petroleum gas (LPG) has been studied experimentally. The  study was conducted in a  cylindrical combustion chamber, and combustion model was spherically expanding flame. The  results showed that the laminar burning velocity of ethanol enriched with 5–10% LPG is higher than that of pure ethanol and that of pure LPG. This is due to the formation of H and OH radicals in the preheating zone, where the reaction occurs to form H2O and release heat. It raises temperature in the preheating zone which contributes to increase in the laminar burning velocity.

Design Analysis of a Micro Gas Turbine Combustion Chamber Burning Natural Gas

2012 ◽  
Author(s):  
André Perpignan V. de Campos ◽  
Fernando L. Sacomano Filho ◽  
Guenther C. Krieger Filho
Keyword(s):  
Experimental Data ◽  
Natural Gas ◽  
Combustion Chamber ◽  
Gas Turbines ◽  
Low Cost ◽  
Mixture Fraction ◽  
Combustion Model ◽  
Inlet Temperature ◽  
Gas Combustion ◽  
Micro Turbine

Gas turbines are reliable energy conversion systems since they are able to operate with variable fuels and independently from seasonal natural changes. Within that reality, micro gas turbines have been increasing the importance of its usage on the onsite generation. Comparatively, less research has been done, leaving more room for improvements in this class of gas turbines. Focusing on the study of a flexible micro turbine set, this work is part of the development of a low cost electric generation micro turbine, which is capable of burning natural gas, LPG and ethanol. It is composed of an originally automotive turbocompressor, a combustion chamber specifically designed for this application, as well as a single stage axial power turbine. The combustion chamber is a reversed flow type and has a swirl stabilized combustor. This paper is dedicated to the diagnosis of the natural gas combustion in this chamber using computational fluid dynamics techniques compared to measured experimental data of temperature inside the combustion chamber. The study emphasizes the near inner wall temperature, turbine inlet temperature and dilution holes effectiveness. The calculation was conducted with the Reynolds Stress turbulence model coupled with the conventional β-PDF equilibrium along with mixture fraction transport combustion model. Thermal radiation was also considered. Reasonable agreement between experimental data and computational simulations was achieved, providing confidence on the phenomena observed on the simulations, which enabled the design improvement suggestions and analysis included in this work.

Effects of Fuel Nozzle Condition on Gas Turbine Combustion Chamber Exit Temperature Distributions

2010 ◽  
Author(s):  
Kristen Bishop ◽  
William Allan
Keyword(s):  
Combustion Chamber ◽  
Ambient Pressure ◽  
Cone Angle ◽  
Operating Conditions ◽  
Spray Cone Angle ◽  
Mixing Processes ◽  
Spray Cone ◽  
Temperature Distributions ◽  
Fuel Nozzle ◽  
Exit Temperature

The effects of fuel nozzle condition on the temperature distributions experienced by the nozzle guide vanes have been investigated using an optical patternator. Average spray cone angle, symmetry, and fuel streaks were quantified. An ambient pressure and temperature combustion chamber test rig was used to capture exit temperature distributions and to determine the pattern factor. The rig tests matched representative engine operating conditions by matching Mach number, equivalence ratio, and fuel droplet size. It was observed that very small deviations (± 10° in spray cone angle) from a nominal distribution in the fuel nozzle spray pattern correlated to increases in pattern factor, apparently due to a degradation of mixing processes, which created larger regions of very high temperature core flow and smaller regions of cooler temperatures within the combustion chamber exit plane. The spray cone angle had the most measureable influence while the effects of spray roundness and streak intensity had slightly less influence. Comparisons were made with published studies conducted on the combustion chamber geometry, and recommendations were made for fuel nozzle inspections.

Investigation of Loss Impact From Production-Like Features in a Compressor Duct Under Engine Realistic Conditions

2017 ◽  
Author(s):  
Fredrik Wallin ◽  
Mark H. Ross ◽  
Max Rusche ◽  
Scott Morris ◽  
Steven Ray
Keyword(s):  
Surface Roughness ◽  
Total Pressure ◽  
Experimental Testing ◽  
Computational Grid ◽  
Test Facility ◽  
Pressure Probe ◽  
Cfd Analysis ◽  
Roughness Model ◽  
Geometrical Features ◽  
Real Geometry

An experimental and numerical investigation of the flow in a compressor duct with engine-realistic in-production features is presented in this paper. The experimental testing was conducted in the ND-FSCC test facility at University of Notre Dame, Indiana, USA. A baseline duct was also tested for back-to-back comparison. The ducts were heavily instrumented; duct inlet and exit flowfields were scanned using a five-hole pressure probe that provided total pressure, velocities and flow angles. Based on the five-hole probe total pressures, duct losses could be assessed. Furthermore the duct inlet boundary layers were traversed and turbulence intensity levels were assessed. For the CFD analysis of the production-like duct, a highly complex computational grid, resolving all the geometrical features present, was used. A previously validated surface roughness model was used to account for the cast aero-surfaces. Both experimental and numerical results show that there is a significant increase in loss for the production-like duct when compared to the baseline duct loss. The CFD results agree very well with experimental results for the baseline duct, which makes it possible to use the experimental data recorded for the production-like duct to validate CFD tools for real geometry effects, such as interface steps and surface roughness for example.

CFD analysis of fluid flow inside a pentroof combustion chamber with different piston shapes

2017 ◽  
Vol 73 (4) ◽  
pp. 281
Author(s):  
M. Manikandan ◽  
Samir Saraswati ◽  
K. Ananthakrishnan
Keyword(s):  
Fluid Flow ◽  
Combustion Chamber ◽  
Cfd Analysis
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