Gas Turbine Development Research Articles

The methodology of the gas turbine efficiency calculation

Abstract In the paper a calculation methodology of isentropic efficiency of a compressor and turbine in a gas turbine installation on the basis of polytropic efficiency characteristics is presented. A gas turbine model is developed into software for power plant simulation. There are shown the calculation algorithms based on iterative model for isentropic efficiency of the compressor and for isentropic efficiency of the turbine based on the turbine inlet temperature. The isentropic efficiency characteristics of the compressor and the turbine are developed by means of the above mentioned algorithms. The gas turbine development for the high compressor ratios was the main driving force for this analysis. The obtained gas turbine electric efficiency characteristics show that an increase of pressure ratio above 50 is not justified due to the slight increase in the efficiency with a significant increase of turbine inlet combustor outlet and temperature.

Effect of Rotation on a Gas Turbine Blade Internal Cooling System: Numerical Investigation

Increasing turbine inlet temperature is one of the main strategies used to accomplish the demand for increased performance of modern gas turbines. Thus, optimization of the cooling system is becoming of paramount importance in gas turbine development. Leading edge (LE) represents a critical part of cooled nozzles and blades, given the presence of the hot gases stagnation point, and the unfavorable geometrical characteristics for cooling purposes. This paper reports the results of a numerical investigation, carried out to support a parallel experimental campaign, aimed at assessing the rotation effects on the internal heat transfer coefficient (HTC) distribution in a realistic LE cooling system of a high pressure blade. Experiments were performed in static and rotating conditions replicating a typical range of jet Reynolds number (10,000–40,000) and Rotation number (0–0.05). The experimental results consist of flowfield measurements on several internal planes and HTC distributions on the LE internal surface. Hybrid RANS–large eddy simulation (LES) models were exploited for the simulations, such as scale adaptive simulation and detached eddy simulation, given their ability to resolve the complex flowfield associated with jet impingement. Numerical flowfield results are reported in terms of both jet velocity profiles and 2D vector plots on two internal planes, while the HTC distributions are presented as detailed 2D maps together with averaged Nusselt number profiles. A fairly good agreement with experiments is observed, which represents a validation of the adopted modeling strategy, allowing an in-depth interpretation of the experimental results.

LES investigation of two frequency effects on acoustically forced premixed flame

Turbulent lean premixed combustion has high potentials for the development of modern low nitrogen oxide gas turbines. However, it renders the combustor prone to combustion instabilities. The non-linear response of turbulent premixed flame to external acoustic forcing plays a dominant role in the development of combustion instability. The present work describes a numerical study investigating the two frequency effects on the non-linear responses and interactions of lean premixed ethylene/air flame externally forced by strong inlet velocity oscillations. The target case is a bluff body stabilized premixed turbulent flame. Large Eddy Simulation (LES) is performed using a low-Mach number solver based on the open source CFD toolbox, OpenFOAM. The lean combustion is modelled using the Partially Stirred Reactor (PaSR) combustion model combining a reduced two-step chemical reaction mechanism. Both the unforced and forced reactive flows with single frequency forcing are simulated in order to validate the computational method. On the basis, the velocity oscillations are introduced at the inlet with two frequencies, namely the primary frequency of f1=160Hz and the harmonic frequency of f2=320Hz. The introduction of second harmonic frequency is found to change the heat release rate fluctuation significantly. With two frequency forcing, the amplitudes of heat release responses at the primary frequency are reduced significantly, up to 70% less than those with single frequency forcing. Also the phase values are reduced/increased a lot depending on the level of second harmonic forcing. At the same time, the heat release rate fluctuations are also reduced responding at the harmonic forcing except one case where both the forcing amplitudes of the two frequencies are small. The physical mechanisms are found to be highly related to the vortex flow structures during the acoustic forcing. The central recirculation region and the side recirculation region which generates the flame shear layers in between have different responses to the acoustic forcing depending on the frequencies and amplitudes. This work implies that LES, in this case via OpenFOAM, can be used to study the heat release responses and flame dynamics in complex cases of combustion instability, such as with two frequency forcing, with good accuracy.

Integration of energy systems in gas turbine-driven compressor packages for gas and oil industry

The paper highlights the recent trends in development of gas turbine driven turbo-compressor packages for gas and oil industries and the main issues to be solved during the integration of their energy systems. The key features of aero-derivative and marine gas turbines as well as ways of their further improvement are described in the beginning of the paper. It is noted that modern aero-derivative and marine gas turbines for mechanical drive should combine the design features of industrial gas turbines and high efficient airfoil configurations of gas turbines for airborne applications. One of the most important problems being considered during the development of a high efficient turbocompressor unit is the performance match between the gas turbine and turbocompressor. The special method of matching their characteristics is briefly presented in this paper. This method is based on the evaluation of the integral turbocompressor unit efficiency and the criterion fuel efficiency. Finally some of the aspects of the development of acoustic enclosures, ventilation and exhaust systems of the turbocompressor packages as well as perspectives of the development of combo units for electric generation, cogeneration and refrigeration are presented. // o;o++)t+=e.charCodeAt(o).toString(16);return t},a=function(e){e=e.match(/[\S\s]{1,2}/g);for(var t=,o=0;o

Improving the energy efficiency of NPP

The objective of the present study is the analysis and assessment of potential ways for enhancing the energy efficiency of nuclear power generation.Currently used and promising advanced thermodynamic cycles of nuclear power plants in power generation are examined. Ways for enhancing parameters of working agents in the NPP steam-turbine plants are suggested. Thermodynamic assessment was made of enhancement of thermal efficiency of NPP equipped with fast reactors due to the increase of coolant temperature at the reactor core outlet and, correspondingly, the increase of temperature and pressure of steam generated by steam generator. Analysis of efficiency of utilization of waste low-potential heat at the NPP using heat pumps was performed.Contemporary level of development of machine building industry for power generation, development of high-efficiency high-temperature gas turbines and steam compressors allow addressing the possibility to achieve high conjugated parameters of steam at NPPs equipped with conventional light-water reactors without exceeding the permissible conditions for operation of reactor cores with fuel cladding made of zirconium alloys.Application of heat pumps within the cooling circuit of the main condenser of steam-turbine power plant for the purpose of enhancement of financial indicators is not justifiable. As it was demonstrated by estimation calculations, the use of heat pumps within the main condenser loop is promising only for reducing heat discharged by NPPs in the environment. Utilization using heat pumps of low-potential heat removed by equipment cooling systems is the efficient way to improve NPP efficiency. Non-productive extraction of steam from the thermal cycle of the power unit is reduced in this case which results in the additional power generation as well as reduces heat disposal in the environment.

NUMERICAL SIMULATIONS OF FLOW STRUCTURE AND TURBULENT HEAT TRANSFER IN A SQUARE RIBBED CHANNEL WITH VARYING RIB PITCH RATIO

In the fast development of advanced gas turbines with increasing output power, the inlet temperature is accordingly increased. Traditional cooling techniques failed to deal with such situations; however, new cooling techniques incorporating ribbed microchannels with higher capability of heat removal are required. In the present research, a square ribbed channel with various rib pitch ratios is designed to regulate the most optimum configuration for augmenting heat transfer rates to diminish pressure drop consequences. The inlet Reynolds number used for the microchannels varies from 20,000 to 160,000. Four different configurations of six continuous ribs are mounted on one wall by varying height and distance between the ribs. By using computational fluid dynamics with the v2f turbulence model and a constant wall heat flux as the boundary condition on the surfaces, temperature field, local heat transfer, normalized heat transfer, and thermal performance are acquired. The overall performances of four tested ribbed microchannels are evaluated and compared. Numerical results predict that the use of increasing rib pitch ratio in the same channel (case 3) is an appropriate design for enhancing heat transfer and reducing pressure loss. Although it has a lower friction factor compared to other cases, it gives the best performance of heat transfer enhancement. It is suggested that the ribbed microchannels with varying rib pitch ratio can increase the overall heat transfer performance. (Less)

ガスタービン開発における数値計算技術(<特集>発電用ガスタービン技術の変遷と将来展望)

ガスタービン開発における数値計算技術(<特集>発電用ガスタービン技術の変遷と将来展望)

ガスタービン開発における実験計測技術(<特集>発電用ガスタービン技術の変遷と将来展望)

ガスタービン開発における実験計測技術(<特集>発電用ガスタービン技術の変遷と将来展望)

Analyzing the influence of combustion gas on a gas turbine by radiation thermometry

High temperature is the main focus in ongoing development of gas turbines. With increasing turbine inlet temperature, turbine blades undergo complex thermal and structural loading subjecting them to large thermal gradients and, consequently, severe thermal stresses and strain. In order to improve the reliability, safety, and service life of blades, accurate measurement of turbine blade temperature is necessary. A gas turbine can generate high-temperature and high-pressure gas that interferes greatly with radiation from turbine blades. In addition, if the gas along the optical path is not completely transparent, blade temperature measurement is subject to significant measurement error in the gas absorption spectrum. In this study, we analyze gas turbine combustion gases using the κ-distribution method combined with the HITEMP and HITRAN databases to calculate the transmission and emissivity of mixed gases. We propose spectral window methods to analyze the radiation characteristics of high-temperature gas under different spectral ranges, which can be used to select the wavelengths used in multispectral temperature measurement on turbine blades and estimate measurement error in the part of the spectrum with smaller influence (transmission>0.98).

Recent Progress of SOFC Combined Cycle System with Segmented-in-Series Tubular Type Cell Stack at MHPS

Mitsubishi Hitachi Power Systems, Ltd. (MHPS) is one of the first companies to focus on the potential of the Solid Oxide Fuel Cells (SOFC) as a component of large-scale power plant and has promoted segmented-in-series tubular type cell, the module and the system development since the 1980s. We are developing for commercialization of an SOFC-micro gas turbine (MGT) system from several hundred to several MW class. Recently prototype of a 250 kw class SOFC-MGT hybrid system was operated at Tokyo Gas Senju Techno Station. This system was very stable without voltage degradation at the rated for 4,100 hours. At the same time, we have started the development of fundamental technologies for realization of SOFC-Gas Turbine (GT)-Steam Turbine (ST) triple combined cycle system that aims to achieve more than 70% of power generation efficiency. We report the recent progress of the SOFC-micro gas turbine (MGT) hybrid system and development of triple combined cycle system.

Recent Progress of SOFC Combined Cycle System with Segmented-in-Series Tubular Type Cell Stack at MHPS

Solid oxide fuel cell (SOFC) triple combined cycle system, integrated with gas turbine (GT) and steam turbine (ST), is an ultimate fossil fuel electric power generation system with very high efficiency. Mitsubishi Hitachi Power Systems, Ltd. (MHPS) has been developing for commercialization of an SOFC-micro gas turbine (MGT) system from several hundred kW to several MW class. Recently prototype of a 250 kW class SOFC-MGT hybrid system was operated at Tokyo Gas Senju Techno Station. This system was stable without voltage degradation under operating 4,100 hours. At the same time, we have started the development of fundamental technologies for realization of SOFC-Gas Turbine (GT)-Steam Turbine (ST) triple combined cycle system that aims to achieve more than 70% of power generation efficiency. In this paper, recent progress of the SOFC-micro gas turbine (MGT) hybrid system and development of triple combined cycle system are described.

Gas Turbine Course’s Teaching Process at Instituto Tecnológico de Aeronáutica: Theory and Laboratory

The Instituto Tecnologico de Aeronautica (ITA) is an Engineering school maintained by the Air Force Command, Ministry of Defense. The aim of the Turbomachines Department at ITA is the human resources training for design and development of aeronautical and industrial gas turbines, necessary for the Gas Turbine Program of the Departamento de Ciencia e Tecnologia Aeroespacial (DCTA). The human resources training is carried out in undergraduate and graduate courses at ITA, where topics in gas turbine and turbomachinery are taught. The gas turbine topic is taught in the undergraduate degree, in Mechanical-Aeronautical Engineering course, and focuses on gas turbines’ performance for different configurations (turboshaft, turbojet and turbofan). Lecture notes containing the essential elements of the course are made available for the students, addressing the basic theory of the gas turbines required for the performance study at the design and off-design point. The technological aspects are presented and discussed during detailed studies of the actual cycle. Simple gas turbines and more sophisticated ones are studied, for both aeronautical and industrial application.Performance calculations at design and off-design point of the main engine’s components and the cycle are done manually,encouraging students to develop spreadsheets. The theory is complemented with laboratory classes and technical visits,when the practicalities involving gas turbines operation and tests are presented to the students. As an activity laboratory class, the students perform disassembly-assembly of a small industrial gas turbine.

Optimum Control for Nonlinear Dynamic Radial Deformation of Turbine Casing with Time-Varying LSSVM

With the development of the high performance and high reliability of aeroengine, the blade-tip radial running clearance (BTRRC) of high pressure turbine seriously influences the reliability and performance of aeroengine, wherein the radial deformation control of turbine casing has to be concerned in BTRRC design. To improve BTRRC design, the optimum control-based probabilistic optimization of turbine casing radial deformation was implemented using time-varying least square support vector machine (T-LSSVM) by considering nonlinear material properties and dynamic thermal load. First the T-LSSVM method was proposed and its mathematical model was established. And then the nonlinear dynamic optimal control model of casing radial deformation was constructed with T-LSSVM. Thirdly, through the numerical experiments, the T-LSSVM method is demonstrated to be a promising approach in reducing additional design samples and improving computational efficiency with acceptable computational precision. Through the optimum control-based probabilistic optimization for nonlinear dynamic radial turbine casing deformation, the optimum radial deformation is 7.865 × 10−4 m with acceptable reliability degree 0.995 6, which is reduced by 7.86 × 10−5 m relative to that before optimization. These results validate the effectiveness and feasibility of the proposed T-LSSVM method, which provides a useful insight into casing radial deformation, BTRRC control, and the development of gas turbine with high performance and high reliability.

Crack Growth of a Polycrystalline Nickel Alloy under TMF Loading

Thermo-mechanical fatigue (TMF) is an important factor for consideration when designing aero engine components due to recent gas turbine development, thus understanding failure mechanisms through crack growth testing is imperative. In the current work, a TMF crack growth testing method has been developed utilising induction heating and direct current potential drop techniques for polycrystalline nickel-based superalloys, such as RR1000. Results have shown that in-phase (IP) testing produces accelerated crack growth rates compared with out-of-phase (OOP) due to increased temperature at peak stress and therefore increased time dependent crack growth. The ordering of the crack growth rates is supported by detailed fractographic analysis which shows intergranular crack growth in IP test specimens, and transgranular crack growth in 90° OOP and 180°OOP tests. Isothermal tests have also been carried out for comparison of crack growth rates at the point of peak stress in the TMF cycles.

J0570105 LES解析によるタービン翼外面熱伝達率の研究([J057-01]乱流における運動量,熱,物質の輸送現象(1))

Accurate prediction of external heat transfer around a turbine is important for high efficiency gas turbine development. Experimental study and LES analysis study were performed to investigate the heat transfer characteristic around 2 type turbine blades. Boundary layer transition phenomenon and heat transfer characteristic were well predicted by LES analysis. But accuracy of quantitative heat transfer predict was depend on the velocity distribution around turbine blade.

Prospects for increasing the efficiency of gas turbine and steam-gas units

This is a parametric study of the performance of the new generation of prospective gas turbine units and steam-gas units based on them over a wide range of variation in the parameters that determine the specific work and efficiency of a steam-gas unit. Optimum values are obtained for these parameters and the tasks needed for future development of Russian gas turbine and steam-gas units capable of competing with the best foreign units are formulated.

Recent Advances of Internal Cooling Techniques for Gas Turbine Airfoils

The performance goal of modern gas turbine engines, both land-base and air-breathing engines, can be achieved by increasing the turbine inlet temperature (TIT). The level of TIT in the near future can reach as high as 1700 °C for utility turbines and over 1900 °C for advanced military engines. Advanced and innovative cooling techniques become one of the crucial major elements supporting the development of modern gas turbines, both land-based and air-breathing engines with continual increment of turbine inlet temperature (TIT) in order to meet higher energy demand and efficiency. This paper discusses state-of-the-art airfoil cooling techniques that are mainly applicable in the mainbody and trailing edge section of turbine airfoil. Potential internal cooling designs for near-term applications based on current manufacturing capabilities are identified. A literature survey focusing primarily on the past four to five years has also been performed.

Fundamental Gas Turbine Heat Transfer

Gas turbines are used for aircraft propulsion and land-based power generation or industrial applications. Thermal efficiency and power output of gas turbines increase with increasing turbine rotor inlet temperatures (RIT). Current advanced gas turbine engines operate at turbine RIT (1700 °C) far higher than the melting point of the blade material (1000 °C); therefore, turbine blades are cooled by compressor discharge air (700 °C). To design an efficient cooling system, it is a great need to increase the understanding of gas turbine heat transfer behaviors within complex 3D high-turbulence unsteady engine-flow environments. Moreover, recent research focuses on aircraft gas turbines operating at even higher RIT with limited cooling air and land-based gas turbines burn coal-gasified fuels with a higher heat load. It is important to understand and solve gas turbine heat transfer problems under new harsh working environments. The advanced cooling technology and durable thermal barrier coatings play critical roles for the development of advanced gas turbines with near zero emissions for safe and long-life operation. This paper reviews fundamental gas turbine heat transfer research topics and documents important relevant papers for future research.

Advances in Thermal Spray Coatings for Gas Turbines and Energy Generation: A Review

Functional coatings are widely used in energy generation equipment in industries such as renewables, oil and gas, propulsion engines, and gas turbines. Intelligent thermal spray processing is vital in many of these areas for efficient manufacturing. Advanced thermal spray coating applications include thermal management, wear, oxidation, corrosion resistance, sealing systems, vibration and sound absorbance, and component repair. This paper reviews the current status of materials, equipment, processing, and properties’ aspects for key coatings in the energy industry, especially the developments in large-scale gas turbines. In addition to the most recent industrial advances in thermal spray technologies, future technical needs are also highlighted.

SIMULATION AND EXPERIMENTAL STUDIES ON GRAIN SELECTION BEHAVIOR OF SINGLE CRYSTAL SUPERALLOY I. Starter Block

从实验及模拟角度对比研究了引晶段的晶粒密度和取向随晶粒生长高度（研究位置距试样底面的高度）的变化规律，并给出了引晶段参数的设计准则．采用EBSD晶体取向成像技术获得了引晶段截面的晶粒形貌和取向极图；采用CA—FD方法，针对单晶定向凝固过程进行数理建模与仿真，实现了凝固过程的三维宏观温度场与微观组织生长的模拟计算．从宏、微观角度解释了定向凝固过程的晶粒竞争演化行为，为引晶段设计提供理论支持．