Gas Turbine Engines For Power Generation Research Articles

Performance Characterization of a Natural Gas–Air Rotating Detonation Engine

An experimental study of a rotating detonation engine (RDE) operating with natural gas and air at elevated chamber pressures and air preheat temperatures was conducted to quantify its performance at conditions representative of land-based power generation gas turbine engines. The thrust produced by the combustor was measured to characterize its work output potential. High-frequency pressure transducers and broadband chemiluminescence measurements of the flame provided information about the wave structure and dynamics. Analysis of common performance metrics demonstrated the necessity of normalizing any RDE performance parameter by the driving system potential, typically the reactant manifold pressure. Application of a thermodynamic performance model to a generic RDE identified the area ratio between the RDE exhaust and injection throats as the primary parameter affecting delivered pressure gain. The model was further applied to draw comparison with experimental measurements of net pressure gain for identical flow conditions. Only one of the two tested injector configurations followed the predicted trends, suggesting that performance of the second was governed by physical processes other than the reactant thermodynamics. Although an absolute pressure gain was not demonstrated, it is promising that the natural gas–air RDE delivered up to 90% of the theoretical performance.

Operability of a Natural Gas–Air Rotating Detonation Engine

A combustor was developed to operate with natural gas and air as the primary propellants at elevated chamber pressures and air preheat temperatures representative of land-based power generation gas turbine engines. Detonation dynamics were studied to characterize the operability of rotating detonation-based pressure gain combustion systems for this application. Measurements of chamber wave dynamics were performed using high-frequency pressure transducers and high-speed imaging of broadband combustion chemiluminescence. The rotating detonation engine was tested with two injector configurations across a broad range of mass flux (), equivalence ratio (0.85–1.2), and oxygen mass fraction (23.2–35%) conditions to determine the effect of operating parameters on the propagation of detonation waves in the combustor. Wave propagation speeds of up to 70% of the mixture Chapman–Jouguet detonation velocity and chamber pressure fluctuations greater than 4 times the mean chamber pressure were observed. Supplementing the air with additional oxygen, varying the equivalence ratio, and enriching the fuel with hydrogen revealed that combustor operability is sensitive to the chemical kinetics of the propellant mixture. Comparing the operational trends of the two injector configurations suggests that one design mixes the incoming propellants more effectively. Although most test conditions exhibited counter-rotating detonation waves within the chamber, the injector design with superior mixing characteristics was able to support single-wave propagation.

Off-design performance of solar Centaur-40 gas turbine engine using Simulink

In the present study, a Simulink model based on Matlab software is used to calculate the off-design running point for single shaft Centaur 40 power generation gas turbine engine. The off-design calculations comprise two models, the first is the operation during engine starting (from 65% to 100% speed, no load) while the other is the engine operation during the loading (constant speed of 100%). For starting model the baseline parameter is the engine speed while the net power is the baseline parameter in the case of loading operation. Herein, the component characteristics maps, the air and air/fuel mixture properties as functions of temperature and the engine design point parameters are introduced to the calculating program. Because of the lack of real component characteristics, scaling law is followed to adapt these characteristics. The loading operation results are then compared with the field results to check the validity of Simulink model. Also the effects of the ambient temperature on the engine performance parameters at the design condition are investigated.

Preparation Methods and Ceramic Materials Selection Guideline for Thermal Barrier Coatings

Thermal barrier coatings (TBCs) are usually applied in aviation and power generation industries, particularly in the gas-turbine engines for power generation. The most common methods for TBCs production include electron beamphysical vapor deposition (EB-PVD) and plasma spraying (PS). The PS TBCs usually show the laminar structure with abundant pores and cracks, whereas the EB-PVD TBCs possess excellent anti-corrosion and anti-oxidation capacities with higher thermal conductivity than PS TBCs. In this review, recent progress on microstructure optimization and failure problems based on the EB-PVD and PS methods was summarized. Several available approaches such as the PS-physical vapor deposition method, solution precursor PS, and suspension PS were reviewed. The ceramic materials selection of TBCs was further discussed. In addition to the YSZ system, the pyrochlore structure considered to be the most potential candidate in the next generation was shown in EP2407579 and EP0992603. Other alternatives, such as YAG-based materials, La-Monazite, and LaMgAl11O19, were shown in US2011236657, US6863999, and CN101928144, respectively. Finally, a number of US patents were discussed, including US5773141, US20120219808, and US20120034491 related to the modified TBCs resistant to environmental pollutants called calcium-alumina-silicate.

Performance Increases for Gas-Turbine Engines Through Combustion Inside the Turbine

In a conventional gas-turbine engine, fuel is burned in separate combustors before the heated high-pressure gas expands through the turbine to provide shaft power for the compressor, fan, propellers, helicoptor rotors, or an electric generator in a ground-based powerplant application. It is proposed in this paper that combustion be continued purposely inside the turbine to increase the efficiency and specific thrust/power of the engine. We term such a turbine with combustion a turbine-burner. A thermodynamic cycle analysis is performed to demonstrate the performance gains of turbojet engines with the turbine burner over the conventional turbojets. Ground-based gas-turbine engines for power generation are also analyzed, with the results showing even better performance gains compared without conventional engines. A mixing-layer analysis with combustion in an accelarated flow similar to the conditions in the turbine burner shows that there is also potential reduction of NOr by using the turbineburner compared with conventional combustors, where the burning is at a constant pressure. Challenges and related research issues that must be addressed to use the turbine-burner technology are identified in this paper.

Nonlinear dynamic simulation of single- and multispool core engines. I - Computational method. II - Simulation, code validation

A new computational method for accurate simulation of the nonlinear, dynamic behavior of single- and multispool core engines, turbofan engines, and power-generation gas turbine engines is presented in Part I of this article. In order to perform the simulation, a modularly structured computer code has been developed that includes individual mathematical modules representing various engine components. The generic structure of the code enables the simulation of arbitrary engine configurations ranging from single-spool thrust generation to multispool thrust/power generation engines under adverse dynamic operating conditions. For precise simulation of turbine and compressor components, row-by-row calculation procedures were implemented that account for the specific turbine and compressor cascade and blade geometry and characteristics.

GETRAN: A Generic, Modularly Structured Computer Code for Simulation of Dynamic Behavior of Aero- and Power Generation Gas Turbine Engines

The design concept, the theoretical background essential for the development of the modularly structured simulation code GETRAN, and several critical simulation cases are presented in this paper. The code being developed under contract with NASA Lewis Research Center is capable of simulating the nonlinear dynamic behavior of single- and multispool core engines, turbofan engines, and power generation gas turbine engines under adverse dynamic operating conditions. The modules implemented into GETRAN correspond to components of existing and new-generation aero- and stationary gas turbine engines with arbitrary configuration and arrangement. For precise simulation of turbine and compressor components, row-by-row diabatic and adiabatic calculation procedures are implemented that account for the specific turbine and compressor cascade, blade geometry, and characteristics. The nonlinear, dynamic behavior of the subject engine is calculated solving a number of systems of partial differential equations, which describe the unsteady behavior of each component individually. To identify each differential equation system unambiguously, special attention is paid to the addressing of each component. The code is capable of executing the simulation procedure at four levels, which increase with the degree of complexity of the system and dynamic event. As representative simulations, four different transient cases with single- and multispool thrust and power generation engines were simulated. These transient cases vary from throttling the exit nozzle area, operation with fuel schedule, rotor speed control, to rotating stall and surge.