Thermo-Structural Analysis of a Micro Gas Turbine Jet- and Recirculation- Stabilized Combustion Chamber

2020 ◽  
Author(s):  
Daniele Cirigliano ◽  
Felix Grimm ◽  
Peter Kutne ◽  
Manfred Aigner
Keyword(s):  
Fluid Dynamics ◽  
High Pressure ◽  
Structural Analysis ◽  
Combustion Chamber ◽  
Gas Turbines ◽  
Thermal Stresses ◽  
Numerical Models ◽  
Equivalent Stress ◽  
Heat Fluxes ◽  
Finite Elements Analysis

Abstract Modern Micro Gas Turbines must be capable to operate at different load points, in order to fulfill the demand of Combined Heat and Power for which they are designed. The combustion chamber structures are therefore subjected to regularly variable thermal loads, yet remaining physically constrained at the rest of the structure. Hence, they experience variable metal temperatures, temperature gradients and thermal stresses which can lead to thermal failure. Typical failure mechanisms in combustion chambers are fatigue and creep. Oxidation can also play an important role. In the present study, Computational Fluid Dynamics methods are used for validation of flow prediction, combustion and heat transfer of an atmospheric combustion chamber. Convective and radiative heat losses towards the ambient are specifically taken into account, leading to better agreement with experimental data from preceding studies. The comparison is presented in this paper. The real-scale machine-operated combustion chamber is then tested at its nominal high-pressure conditions. In this respect, the hereby validated numerical models are employed to simulate the high-pressure operation. A fully coupled Thermo-Structural analysis is performed in order to account for heat fluxes within the solid materials. By so doing, wall temperature distributions can be obtained. The results from Fluid Dynamics simulations serve as input for a Finite Elements Analysis, which provides equivalent stress, strain and deformation distributions by using a linear elastic mechanical model. Such distributions highlight the most critical areas, allowing a first estimate of the components’ life according to thermo-mechanical fatigue. The additional influence of Creep and Oxidation is currently under development at DLR Stuttgart and will be presented in subsequent works.

Micro Gas Turbine Cycle Humidification for Increased Flexibility: Numerical and Experimental Validation of Different Steam Injection Models

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Ward De Paepe ◽  
Massimiliano Renzi ◽  
Marina Montero Carrerro ◽  
Carlo Caligiuri ◽  
Francesco Contino
Keyword(s):  
Combustion Chamber ◽  
Gas Turbines ◽  
Numerical Models ◽  
Steam Injection ◽  
Power Production ◽  
Cycle Performance ◽  
Small Scale ◽  
Model Parameters ◽  
Complete Combustion ◽  
The Impact

With the current shift from centralized to more decentralized power production, new opportunities arise for small-scale combined heat and power (CHP) production units like micro gas turbines (mGTs). However, to fully embrace these opportunities, the current mGT technology has to become more flexible in terms of operation—decoupling the heat and power production in CHP mode—and in terms of fuel utilization—showing flexibility in the operation with different lower heating value (LHV) fuels. Cycle humidification, e.g., by performing steam injection, is a possible route to handle these problems. Current simulation models are able to correctly assess the impact of humidification on the cycle performance, but they fail to provide detailed information on the combustion process. To fully quantify the potential of cycle humidification, more advanced numerical models—preferably validated—are necessary. These models are not only capable of correctly predicting the cycle performance, but they can also handle the complex chemical kinetics in the combustion chamber. In this paper, we compared and validated such a model with a typical steady-state model of the steam injected mGT cycle based on the Turbec T100. The advanced one is an in-house MATLAB model, based on the NIST database for the characterization of the properties of the gaseous compounds with the combustion mechanisms embedded according to the Gri-MEch 3.0 library. The validation one was constructed using commercial software (Aspen Plus), using the more advance Redlich-Kwong-Soave (RKS)- Boston-Mathias(BM) property method and assuming complete combustion by using a Gibbs reactor. Both models were compared considering steam injection in the compressor outlet or in the combustion chamber, focusing only on the global cycle performance. Simulation results of the steam injection cycle fueled with natural gas and syngas showed some differences between the two presented models (e.g., 5.9% on average for the efficiency increase over the simulated steam injection rates at nominal power output for injection in the compressor outlet); however, the general trends that could be observed are consistent. Additionally, the numerical results of the injection in the compressor outlet were also validated with steam-injection experiments in a Turbec T100, indicating that the advanced MATLAB model overestimates the efficiency improvement by 25–45%. The results show the potential of simulating the humidified cycle using more advanced models; however, in future work, special attention should be paid to the experimental tuning of the model parameters in general and the recuperator performance in particular to allow correct assessment of the cycle performance.

scholarly journals Effects of Damaged Rotor Blades on the Aerodynamic Behavior and Heat-Transfer Characteristics of High-Pressure Gas Turbines

Mathematics ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 627
Author(s):  
Thanh Dam Mai ◽  
Jaiyoung Ryu
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Rotor Blade ◽  
High Speed ◽  
Power Plants ◽  
Thermal Stresses ◽  
Turbine Blades ◽  
Combined Cycle

Gas turbines are critical components of combined-cycle power plants because they influence the power output and overall efficiency. However, gas-turbine blades are susceptible to damage when operated under high-pressure, high-temperature conditions. This reduces gas-turbine performance and increases the probability of power-plant failure. This study compares the effects of rotor-blade damage at different locations on their aerodynamic behavior and heat-transfer properties. To this end, we considered five cases: a reference case involving a normal rotor blade and one case each of damage occurring on the pressure and suction sides of the blades’ near-tip and midspan sections. We used the Reynolds-averaged Navier-Stokes equation coupled with the k − ω SST γ turbulence model to solve the problem of high-speed, high-pressure compressible flow through the GE-E3 gas-turbine model. The results reveal that the rotor-blade damage increases the heat-transfer coefficients of the blade and vane surfaces by approximately 1% and 0.5%, respectively. This, in turn, increases their thermal stresses, especially near the rotor-blade tip and around damaged locations. The four damaged-blade cases reveal an increase in the aerodynamic force acting on the blade/vane surfaces. This increases the mechanical stress on and reduces the fatigue life of the blade/vane components.

Predicting the Influence of Microporosity on the Mechanical Properties and Fracture Behavior of High-Pressure Die-Cast AM50 Magnesium Alloy

2014 ◽  
Vol 670-671 ◽  
pp. 90-94
Author(s):  
X. Sun ◽  
Z.Y. Cao ◽  
H.F. Liu ◽  
W. Jiang ◽  
L.P. Liu
Keyword(s):  
High Pressure ◽  
Stress Field ◽  
Tensile Properties ◽  
Fracture Behavior ◽  
Numerical Models ◽  
Equivalent Stress ◽  
Die Cast ◽  
Areal Fraction ◽  
Am50 Alloy ◽  
Power Law Equation

In this paper, experimental and finite element modeling methods were adopted to investigate the effects of microporosity on the tensile properties and fracture behavior of high-pressure die-casting (HPDC) AM50 alloy. By specimen-to-specimen fractographic analysis, the variability in tensile properties could be quantitatively correlated with the areal fraction of the porosity presented in the corresponding fracture surfaces by using a simple power law equation. Numerical models of synthetic microstructures with different pore sizes, areal fractions of pores and pore distributions were established. Based on the experimental and numerical simulation results, it could be concluded that the fracture will initially occur in the region where has the highest intensity of equivalent stress field (i.e., contains the most highly localized cluster of pores and shrinkage), and then, fracture crack will fast propagate through the adjacent regions which have the relatively high intensity of stress field.

A High-Pressure Water Mist System: Clean Fire Protection for Gas Turbines

2005 ◽  
Author(s):  
Heikki Voutilainen ◽  
Herbert Rohrbacher
Keyword(s):  
High Pressure ◽  
Fire Protection ◽  
Gas Turbines ◽  
Thermal Stresses ◽  
Health And Safety ◽  
Droplet Size Distribution ◽  
Water Mist ◽  
Third Party ◽  
Protection Systems ◽  
Pressure Water

Modern high-pressure water mist systems are an advanced choice for rotating machinery fire protection. High-pressure water mist systems can provide: • Proven extinguishing efficiency, • Proven capability to protect equipment from thermal stresses, • Tolerance to poor enclosure integrity, • A safe and reliable alternative to gaseous systems, and • An environmentally friendly alternative to dry chemicals, halons and halon alternatives. Generally, the systems have total flooding design, which is the most appropriate for protecting rotating equipment in their purpose-built enclosures. Fine water mist with a specific application rate, droplet size distribution and high discharge momentum is used to fill the enclosure quickly and completely. For all fire protection systems, third party testing and appraisal is important. FM and VdS have approved gas turbine fire protection systems for enclosures up to 500m3, while systems for enclosures up to 3300 m3 are (2004) within approval process. This paper explains the water mist system basic terminology and fundamentals. The paper then discusses system design requirements and features. In the end, health and safety, as well as environmental aspects are reviewed.

scholarly journals COLD FLOW NUMERICAL ANALYSIS OF GAS MICROTURBINE COMBUSTION CHAMBER THROUGH CFD TOOL

2019 ◽  
Vol 18 (1) ◽  
pp. 29
Author(s):  
G. K. Caetano ◽  
J. F. T. de Carvalho ◽  
J. S. Rosa
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Combustion Chamber ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Reverse Flow ◽  
Ideal Point ◽  
Random Motion ◽  
Design Data ◽  
Cold Flow

Gas turbines are equipment used mainly in the generation of electric energy. They have as one of their main components the combustion chamber. Therefore, it is relevant to study the characteristics of this component, in order to reach a satisfactory operation. In this context, this paper presents an analysis of a combustion chamber applied to a gas turbine with a cold flow approach using the numerical theoretical method, through the computational fluid dynamics technique. In this experiment, the software Abaqus CFD (computational fluid dynamics) – present in the 3DExperience platform – and the finite volume method are used. The objective was to evaluate the flow, pressure and velocity profiles during the single-phase flow. The gas turbine prototype is configured using a combustion chamber of reverse flow type in order to decrease flow velocity and increase the combustion efficiency. Based on input data obtained from practical experiments, the calculation of the number and Reynolds confirmed – according to the literature of fluid mechanics – the occurrence of a flow classified as turbulent, with chaotic and random motion, what allows defining the ideal point of injection from analysis of velocity plots with stream lines. In addition, a Mach number smaller than 0.3 confirms the theory of having an incompressible flow, in which compressibility effects can be disregarded. The analysis of mass flow rates of the combustion zones made it possible to evaluate maximum differences of 3% between the design data and the one found in the study. To determine the inherent error of the mesh in the CFD study was calculated through the grid conference method, the value found was around 2.68%.

Aerothermal Prediction of an Aeronautical Combustion Chamber Based on the Coupling of Large Eddy Simulation, Solid Conduction and Radiation Solvers

2015 ◽  
Author(s):  
Sandrine Berger ◽  
Stéphane Richard ◽  
Gabriel Staffelbach ◽  
Florent Duchaine ◽  
Laurent Gicquel
Keyword(s):  
Heat Transfer ◽  
Large Eddy Simulation ◽  
Combustion Chamber ◽  
Gas Turbines ◽  
Thermal Environment ◽  
Heat Fluxes ◽  
High Fidelity ◽  
Eddy Simulation ◽  
Precise Knowledge ◽  
Large Eddy

A precise knowledge of the thermal environment is essential for gas turbines design. Combustion chamber walls in particular are subject to strong thermal constraints. It is thus essential for designers to characterize accurately the local thermal state of such devices. Today, the determination of wall temperatures is performed experimentally by complex thermocolor tests. To limit such expensive experiments and integrate the knowledge of the thermal environment earlier in the design process, efforts are currently performed to provide high fidelity numerical tools able to predict the combustion chamber walls temperature. Many coupled physical phenomena are involved: turbulent combustion, convection and mixing of hot products and cold flows, conduction in the solid parts as well as gas to gas, gas to wall and wall to wall radiative transfers. The resolution of such a multiphysics problem jointly in the fluid and the solid domains can be done numerically through the use of several dedicated numerical and algorithmic approaches. In this paper, a partitioned coupling methodology is used to investigate the solid steady state wall temperature of a helicopter combustor in take-off conditions. The methodology relies on a high fidelity Large Eddy Simulation reacting flow solver coupled to conduction and radiative solvers. Different computations are presented in order to assess the role of each heat transfer process in the temperature field. A conjugate heat transfer simulation is first proposed and compared with experimental thermocolor tests. The effect of radiation is then investigated comparing relative importance of convective and radiative heat fluxes.

Multidimensional Modeling of Temperature Distribution in Engine Combustion Chamber

2011 ◽  
Author(s):  
Yuanhong Li ◽  
Song-Charng Kong
Keyword(s):  
Heat Conduction ◽  
Combustion Chamber ◽  
Thermal Stresses ◽  
Combustion Process ◽  
Numerical Procedure ◽  
Heat Fluxes ◽  
Operating Conditions ◽  
Uniform Temperature ◽  
Temperature Distributions ◽  
Engine Combustion

Heat conduction calculations are coupled with in-cylinder combustion modeling for engine simulation in this study. Heat transfer on the fluid-solid interface will affect the in-cylinder combustion process, emissions formation, and thermal loading on the combustion chamber surface. Full knowledge of heat fluxes on the interface is important in helping improve engine efficiency, reduce exhaust emissions, and reduce combustion chamber thermal stresses. To account for the unsteady, non-uniform temperature distributions on the combustion chamber surface, a fully coupled numerical procedure was developed and applied to calculate in-cylinder flows and heat conduction in solids simultaneously. The current approach was first validated against analytical heat conduction solutions. The model was then applied to simulate diesel engine combustion under different operating conditions. Unsteady, non-uniform temperature distributions on the piston surface were successfully predicted. Global engine parameters including in-cylinder pressure, heat release rate, and emissions were also comparable to the experimental data.

Micro Gas Turbine Cycle Humidification for Increased Flexibility: Numerical and Experimental Validation of Different Steam Injection Models

2018 ◽  
Author(s):  
Ward De Paepe ◽  
Massimiliano Renzi ◽  
Marina Montero Carrerro ◽  
Carlo Caligiuri ◽  
Francesco Contino
Keyword(s):  
Combustion Chamber ◽  
Gas Turbines ◽  
Numerical Models ◽  
Steam Injection ◽  
Power Production ◽  
Cycle Performance ◽  
Small Scale ◽  
Model Parameters ◽  
Complete Combustion ◽  
The Impact

With the current shift from centralized to more decentralized power production, new opportunities arise for small-scale Combined Heat and Power (CHP) production units like micro Gas Turbines (mGTs). However, to fully embrace these opportunities, the current mGT technology has to become more flexible in terms of operation — decoupling the heat and power production in CHP mode — and in terms of fuel utilization — showing flexibility in the operation with different Lower Heating Value (LHV) fuels. Cycle humidification e.g. by performing steam injection, is a possible route to handle these problems. Current existing simulation models are able to correctly assess the impact of humidification on the cycle performance, but they fail to provide detailed information on the combustion process. To fully quantify the potential of cycle humidification, more advanced numerical models — preferably validated — are necessary. These models are not only capable of correctly predicting the cycle performance, but they can also handle the complex chemical kinetics in the combustion chamber. In this paper, we compared and validated such a model with a typical steady-state model of the steam injected mGT cycle based on the Turbec T100. The advanced one is an in-house MATLAB® model, based on the NIST database for the characterization of the properties of the gaseous compounds with the combustion mechanisms embedded according to the Gri-MEch 3.0 library. The validation one was constructed using commercial software (Aspen® Plus), using the more advance RKS-BM property method and assuming complete combustion by using a Gibbs reactor. Both models were compared considering steam injection in the compressor outlet or in the combustion chamber, focussing only on the global cycle performance. Simulation results of the steam injection cycle fuelled with natural gas and syngas showed some differences between the two presented models (e.g. 5.9% on average for the efficiency increase over the simulated steam injection rates at nominal power output for injection in the compressor outlet); however, the general trends that could be observed are consistent. Additionally, the numerical results of the injection in the compressor outlet were also validated with steam-injection experiments in a Turbec T100, indicating that the advanced MATLAB® model overestimates the efficiency improvement by 25 % to 45 %. The results show the potential of simulating the humidified cycle using more advanced models; however, in future work, special attention should be paid to the experimental tuning of the model parameters in general and the recuperator performance in particular to allow correct assessment of the cycle performance.

scholarly journals CFD Investigation of Trout-Like Configuration Holding Station near an Obstruction

Fluids ◽  
2021 ◽  
Vol 6 (6) ◽  
pp. 204
Author(s):  
Kamran Fouladi ◽  
David J. Coughlin
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Laboratory Experiment ◽  
Numerical Models ◽  
Interaction Model ◽  
Underwater Vehicle ◽  
Water Stream ◽  
Hydrodynamic Analysis ◽  
Structure Interaction ◽  
Vehicle Systems

This report presents the development of a fluid-structure interaction model using commercial Computational fluid dynamics software and in-house developed User Defined Function to simulate the motion of a trout Department of Mechanical Engineering, Widener University holding station in a moving water stream. The oscillation model used in this study is based on the observations of trout swimming in a respirometry tank in a laboratory experiment. The numerical simulations showed results that are consistent with laboratory observations of a trout holding station in the tank without obstruction and trout entrained to the side of the cylindrical obstruction. This paper will be helpful in the development of numerical models for the hydrodynamic analysis of bioinspired unmanned underwater vehicle systems.

scholarly journals Trans-lithospheric diapirism explains the presence of ultra-high pressure rocks in the European Variscides

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Petra Maierová ◽  
Karel Schulmann ◽  
Pavla Štípská ◽  
Taras Gerya ◽  
Ondrej Lexa
Keyword(s):  
High Pressure ◽  
Numerical Models ◽  
Classical Concept ◽  
Plate Interface ◽  
Ultra High Pressure ◽  
Common Process ◽  
Mountain Belts ◽  
Collisional Orogens ◽  
Rock Association ◽  
European Variscides

AbstractThe classical concept of collisional orogens suggests that mountain belts form as a crustal wedge between the downgoing and overriding plates. However, this orogenic style is not compatible with the presence of (ultra-)high pressure crustal and mantle rocks far from the plate interface in the Bohemian Massif of Central Europe. Here we use a comparison between geological observations and thermo-mechanical numerical models to explain their formation. We suggest that continental crust was first deeply subducted, then flowed laterally underneath the lithosphere and eventually rose in the form of large partially molten trans-lithospheric diapirs. We further show that trans-lithospheric diapirism produces a specific rock association of (ultra-)high pressure crustal and mantle rocks and ultra-potassic magmas that alternates with the less metamorphosed rocks of the upper plate. Similar rock associations have been described in other convergent zones, both modern and ancient. We speculate that trans-lithospheric diapirism could be a common process.

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