Pressure gain combustion for gas turbines Research Papers (original) (raw)

Currently, the usefulness of gas turbines in the power generation business cannot be undermined. But to get the most value from their use, they should be operated in a way to maximise power output, minimise fuel consumption with increased thermal efficiency and minimal negative impact on the environment. This research aims at improving the power output of GT 20, which will also help to improve its performance; and will be significant at providing more power to Nigeria’s national grid from the unit for increased production activities. Experimental plants GT 20 and GGTPP were compared with a model plant used to simulate their behaviour. The results of the study show that GT 20 maximum power output from its operation was 92MW with efficiency of 0.34 at a pressure ratio of 10.27. Comparison made between GT 20 and the two other power plants – GGTPP and the model indicate that the low performance of GT 20 was due to unfavourable operating conditions of the unit, but the unit is a much older plant. A mix of optimisation variables of mass flow, compressor inlet temperature, turbine inlet temperature, and pressure ratio were applied to the model and used to optimise GT 20 and its power output. The plant has been optimised at a power output of 100.07 MW and an efficiency of 0.35, with improvements in its performance measures by 5%, 2.94%, and 8.77% in specific fuel consumption, overall efficiency and power output respectively.

This paper presents the failure analysis of the turbine blade of a gas turbine engine 9E GE type, installed in a certain type of simple systems consisting of the gas turbine driving an electrical power generator. A non-linear finite element method was utilized to determine the stress state of the blade segment under operating conditions. High stress zones were found at the region of the lower fir-tree slot, where the failure occurred. A computation was also performed with excessive rotational speed. Attention of this study is devoted to the mechanisms of damage of the turbine blade and also the critical high stress areas.

gas turbine combustion info

- by Ramsés Alemān
- •
- Pressure gain combustion for gas turbines

- by Barhm Mohamad
- •
- Mechanical Engineering, Materials Science, Combustion, Heat Transfer

This paper describes a new method for calculating the performance of pressure gain combustors for gas turbine applications. The method judges the value of a combustor based on the flow's increased potential to do shaft work from combustor inlet to exit. This potential is defined as the work that could be extracted from the flow by a reversible adiabatic turbine exhausting to the combustor supply pressure. A new performance metric, the Rayleigh efficiency, is defined as the increased potential of the flow to do shaft work divided by the heat input. A novel control volume analysis is used, which directly links this performance metric to source terms within the combustor. Two primary source terms are shown: The first is a thermal creation term, which occurs in regions of the flow where combustion heat release occurs at pressures above that of the environment and acts to raise the flow's potential to do shaft work. The term is a nonlinear analog of Lord Rayleigh's acoustic energy creation term, from his 1878 thermoacoustic criterion. The second term is a viscous destruction term that always acts to reduce the flow's potential to do shaft work. In the final part of the paper, the utility of the method is demonstrated using experimental measurements and computational predictions from a SNECMA (Société nationale d'études et de construction de moteurs d'aviation)/ Lockwood-type valveless pulse combustor. The analysis enables a number of previously unanswered questions about pulse combustors to be answered.

A heavy duty gas turbine rotor operates in a highly nonlinear environment. It is often taken to thermal transients and over-speed events. The source of excitations often excites the blades during in-service life. Various stresses generated in the turbine rotor are not only due to centrifugal forces but also due to wake forces generated during the flow through airfoil, which later generates fatigue, Vibratory and creep loads. Structural failures may occur due to various uncertainties involved in the operation of gas turbines such as speed loads, over-speeding and component manufacturing deviations. If catastrophic rotor failures occur, they commonly result in lengthy forced outages and severe economic penalties to the affected utilities. In the present work, assessment of structural integrity of Integrated bladed rotor assessment is accomplished through conduction of an Finite Element analysis blended with classical theories. The structural analysis results of IBR is compared with Bladed Disc assembly to highlight the effect of Contact at Blade Butting zone on frequency response along with Integrated Model(IBR) for a given flow conditions and airfoil. In addition to evaluation of structural strength in the rotor disc components, failures due to vibrations are also quite apparent in the Gas turbine blades. An attempt is made to investigate the resonance points at operating speeds, disk mode participations if any and retrieve excitation frequency modes, Campbell, SAFE (Singh's Advanced Frequency Evaluation Diagram) are generated and analyzed to evaluate the separation margins for Blade and disk integrity.

The performance of a gas turbine is significantly affected by the environmental conditions. Net power output of a gas turbine can be increased by reducing the compressor inlet air temperature. There are different techniques used for inlet air cooling of the gas turbines. These techniques are evaporative coolers, spray inlet coolers or fogging systems, and mechanical refrigeration or chillers where a heat exchanger cools the inlet air. To improve the efficiency of gas turbine power plants, Ice Thermal Energy Storage (ITES) systems can be used as inlet cooling system.
The aim of this study is to determine the use of an ITES system for a 239 MW powered gas turbine cycle, which is located in Bursa / Turkey. The performance of the system was investigated for full load conditions. Energy and exergy analysis were done by using last decade’s meteorological weather data. The results showed that utilizing the ITES system boosted the net power up to 12.60 %.

- by Muhsin Kiliç and +1
- •
- Thermal Engineering, Thermodynamics, Pressure gain combustion for gas turbines, GAS TURBINE

The climate condition affects the performance of the combined-cycle power plants. The efficiency of the combined
cycle is significantly influenced by the temperature, pressure and humidity of the air. When the ambient air
temperature increases, the density of the air decreases, and it leads to a reduction of power generated by the gas
turbine. In this work, the energy and exergy analysis of a commercial gas turbine, with inlet air cooling, was
performed. The effects of fogging system on gas-turbine performance studied. For this aim, the energy and exergy
balances were obtained for each piece of equipment. Calculations have been made for four different cases for the
regarded gas turbine system. Furthermore, exergetic efficiency, exergy destruction rates and improvement
potentials were obtained, and the results of the study demonstrated graphically. It is concluded that the net power
output of the gas turbine system increased at lower inlet temperatures and exergy destruction rates occurred from
highest to lowest as combustion chamber (CC), gas turbine (GT) and air compressor (AC), respectively.

- by Umit Unver and +1
- •
- Thermal Engineering, Thermodynamics, Pressure gain combustion for gas turbines, GAS TURBINE
- by Chris Ward
- •
- Thermodynamics, Pressure gain combustion for gas turbines

Aviation plays a key role in economic prosperity and quality of lifestyle. However there is an increasing concern that current trends of consumption of natural resources cannot continue. It is imperative that major targeted investments are made into economical and reliable environment friendly propulsion and power solutions. A significant amount of this investment will be in the aerospace sector. A well utilised civil aircraft may burn more than 2000 times its weight in fuel during its life, so the examination of the propulsion system is essential from an environmental point of view. A preliminary parametric study for geared, intercooled and/or recuperated turbofan for short range commercial transport applications has been performed with regard to fuel consumption and emissions. A high by-pass ratio turbofan engine with performance characteristics and technology from the year 2000 was set up as a baseline. The results offer interesting qualitative comparisons showing that, for instance, a recuperated engine will yield a lower fuel burn for lower OPR values. An engine with a mid-compressor intercooler may give significant reduction of NOx emissions whilst increasing the amount of CO2 . The intercooled and recuperated cycle offers higher thermal efficiencies (i.e. higher fuel consumption benefit) in comparison to other cycles at medium OPR values; therefore NOx formation may be reduced as well as the engine core weight. Additionally, the inherent advantage of high BPR against low BPR turbofans in terms of SFC is evident (GTF). Clearly, therefore, an increase of BPR is an inevitable solution for the reduction of both fuel consumption and the level of noise produced, however this may involve NOx and integration penalties, hence innovative cycles (e.g.: ICR) and state of the art combustor technology (e.g.: PERM and LDI combustors) must be considered. This is first on the series of work that would be carried out on the cycles being proposed in this paper. Further work on the issues of weight, noise, aircraft performance, other emissions, economics, etc, so-called a multidisciplinary objective assessment, would be published when completed. Also, at this time the design has been limited to take-off being the point of maximum aerodynamic performance. An extension to full mission is currently under investigation.
Paper No. GT2007-27234, pp. 95-102; 8 pages
doi:10.1115/GT2007-27234
ASME Turbo Expo 2007: Power for Land, Sea, and Air
Volume 3: Turbo Expo 2007
Montreal, Canada, May 14–17, 2007
Conference Sponsors: International Gas Turbine Institute
ISBN: 0-7918-4792-6 | eISBN: 0-7918-3796-3

Recently a considerable effort was made to understand the gas- and thermodynamics of wave rotor combustion technology. Pressure-gain combustors potentially have superior performance over conventional combustors due to their unsteady flow behaviour. Wave rotor combustion provides semi-constant volume combustion and could be integrated in the steady-flow gas turbine. However, a feasibility study to assess the economical and environmental aspects of this concept has not been conducted for short-range missions.
Preliminary Multidisciplinary Design Framework was developed to assess novel and radical engine cycles. The tool comprises modules to evaluate noise, emissions and environmental impact. Uncertainty can be accounted for with Monte Carlo simulation.
The geared turbofan with constant volume combustor is simulated and benchmarked against a baseline geared turbofan engine. Results indicate that the former complies with CAEP/6 and FAR Part 36 regulations for noise and emissions. Furthermore, acquisition cost of the engine is higher, but engine direct operating cost decreases by 25.2%. The technology requires further development to meet future noise and emissions requirements.

The performance of a gas turbine is significantly affected by the environmental conditions. Net power output of a gas turbine can be increased by reducing the compressor inlet air temperature. There are different techniques used for inlet air cooling of the gas turbines. These techniques are evaporative coolers, spray inlet coolers or fogging systems, and mechanical refrigeration or chillers where a heat exchanger cools the inlet air. To improve the efficiency of gas turbine power plants, Ice Thermal Energy Storage (ITES) systems can be used as inlet cooling system. The aim of this study is to determine the use of an ITES system for a 239 MW powered gas turbine cycle, which is located in Bursa / Turkey. The performance of the system was investigated for full load conditions. Energy and exergy analysis were done by using last decade’s meteorological weather data. The results showed that utilizing the ITES system boosted the net power up to 12.60 %.

The climate condition affects the performance of the combined-cycle power plants. The efficiency of the combined cycle is significantly influenced by the temperature, pressure and humidity of the air. When the ambient air temperature increases, the density of the air decreases, and it leads to a reduction of power generated by the gas turbine. In this work, the energy and exergy analysis of a commercial gas turbine, with inlet air cooling, was performed. The effects of fogging system on gas-turbine performance studied. For this aim, the energy and exergy balances were obtained for each piece of equipment. Calculations have been made for four different cases for the regarded gas turbine system. Furthermore, exergetic efficiency, exergy destruction rates and improvement potentials were obtained, and the results of the study demonstrated graphically. It is concluded that the net power output of the gas turbine system increased at lower inlet temperatures and exergy destruction rates oc...

- by Mehmet Ismailoðlu and +1
- •
- Thermal Engineering, Pressure gain combustion for gas turbines, GAS TURBINE, Chemical thermodynamics

This paper presents the development of a tool for EnVironmental Assessment (EVA) of novel propulsion cycles
implementing the Technoeconomical Environmental and Risk
Analysis (TERA) approach. For nearly 3 decades emissions certification and legislation has been mainly focused on the
landing and take-off cycle. Exhaust emissions measurements of
NOx, CO and unburned hydrocarbons are taken at Sea Level
Static (SLS) conditions for 4 different power settings (idle, descent, approach and take-off) and are consecutively used for
calculating the total emissions during the ICAO landing and
take-off cycle. With the global warming issue becoming ever
more important, stringent emissions legislation is soon to
follow, focusing on all flight phases of an aircraft.
Unfortunately, emissions measurements at altitude are either
extremely expensive, as in the case of altitude test facility
measurements, or unrealistic, as in the case of direct in flight
measurements. Compensating for these difficulties, various
existing methods can be used to estimate emissions at altitude
from ground measurements.
Such methods, however, are of limited help when it comes
to assessing novel propulsion cycles or existing engine configurations with no SLS measurements available. The
authors are proposing a simple and fast method for the
calculation of SLS emissions, mainly implementing ICAO
exhaust emissions data, corrections for combustor inlet
conditions and technology factors. With the SLS emissions
estimated, existing methods may be implemented to calculate
emissions at altitude. The tool developed couples emissions
predictions and environmental models together with engine and aircraft performance models in order to estimate the total
emissions and Global Warming Potential of novel engine
designs during all flight phases (i.e. the whole flight cycle). The
engine performance module stands in the center of all
information exchange.
In this study, EVA and the described emissions prediction
methodology have been used for the preliminary design analysis of three spool high bypass ratio turbofan engines. The
capability of EVA to radically explore the design space available in novel engine configurations, while accounting for fuel burn and global warming potential during the whole flight
cycle of an aircraft, is illustrated.

—To inspect the debasement of energy amid a practice, the generation of entropy and the loss of work opportunities, exergy is investigated. This examination gives an option plan to guarantee predominant execution of a force plant. This study performed an exergetic investigation for a Baiji plant with a gas-turbine of limit 159-MW. Every part of the system was tried as per the laws of mass and energy conversion. The aspects under thought were the quantitative exergy parity for the whole system and for every part, separately. At various temperatures, rate of irreversibility of system segments, productivity of exergy and the effectiveness imperfections were highlighted for every part and for the entire plant. The exergy stream of a material is ordered into the groupings of warm, mechanical and substance exergy in this study and a surge of entropy-creation. Fuel oil of low heating value estimation of 42.9 MJ/kg was utilized as the fuel. The assessment tended to the topic of how the vacillations in cycle temperatures impact the exergetic productivity and exergy annihilation in the plant. The rate of exergy devastation in the turbine was around 5.4% while that in the burning load was around 36.4%. At the point when a 14°C ascent was done in the temperature, exergy productivity for the ignition chamber and the turbine was computed to be 45.43% and 68.4%, separately. As per the consequences of the study, the ignition chamber and turbine are observed to be boss method for irreversibilities in the plant. Additionally, it was recognized that the exergetic productivity and the exergy pulverization are extensively subject to the adjustments in the turbine delta temperature. On the premise of these outcomes, suggestions are introduced for progression of the plant.

- by Anestis Kalfas and +2
- •
- Mechanical Engineering, Aerospace Engineering, Aeronautical Engineering, Pressure gain combustion for gas turbines

Recently a considerable effort was made to understand the gas- and thermodynamics of wave rotor combustion technology. Pressure-gain combustors potentially have superior performance over conventional combustors due to their unsteady flow behaviour. Wave rotor combustion provides semi-constant volume combustion and could be integrated in the steady-flow gas turbine. However, a feasibility study to assess the economical and environmental aspects of this concept has not been conducted for short-range missions.
Preliminary Multidisciplinary Design Framework was developed to assess novel and radical engine cycles. The tool comprises modules to evaluate noise, emissions and environmental impact. Uncertainty can be accounted for with Monte Carlo simulation.
The geared turbofan with constant volume combustor is simulated and benchmarked against a baseline geared turbofan engine. Results indicate that the former complies with CAEP/6 and FAR Part 36 regulations for noise and emissions.
Furthermore, acquisition cost of the engine is higher, but engine direct operating cost decreases by 25.2%. The technology requires further development to meet future noise and emissions requirements.
J. Eng. Gas Turbines Power 132(6), 061702 (Mar 24, 2010) (8 pages) doi:10.1115/1.4000135
http://gasturbinespower.asmedigitalcollection.asme.org/article.aspx?articleid=1428416