Development of a Small Single- and Two-Shaft Gas Turbine for Military Applications

1964 ◽  
Vol 179 (1) ◽  
pp. 343-364 ◽  
Author(s):  
K. Petrie

In the last two decades there has been a progressive increase in the scope of small gas turbine development and application, both in commercial and military fields. Technological advances in the military field have created demands for prime movers able to meet more stringent operational requirements. An environment now exists in the U.S. Armed Forces conducive to the acceptance and use of small gas turbines that can be adapted to the many specialized applications demanding distinctive physical characteristics. In 1957, the U.S. Bureau of Naval Weapons entered into a contract with Solar, a Division of International Harvester Company, for the design and development of a small, lightweight, single-shaft gas turbine engine to power a one-man helicopter. Rated at 55 s.h.p. for 100°F ambient conditions, the engine design requirements were based on simplicity of operation and maintenance, low production cost, and a short development time. These factors were considered more important than optimum specific power, fuel consumption and weight. A two-shaft version of this engine was also required to power a one-man flying platform. To facilitate the required low engine airflow, weight and rugged characteristics, a single-stage centrifugal compressor and radial inflow turbine, mounted back to back, were selected. A unique feature of the two-shaft engine was the simple method of achieving two-shaft capability by using the exducer portion of the radial turbine as a power turbine. This design resulted in both engines having the same nominal performance, weight and envelope dimensions, with maximum component interchangeability. A comprehensive aerodynamic development programme was undertaken to improve component efficiencies and various aspects of this programme are discussed. Based on favourable results from this programme, the building and development of an uprated engine was undertaken. By incorporating a modified compressor, a 38 per cent increase in s.h.p. and a 6 per cent decrease in specific fuel consumption (s.f.c.) was obtained. Probably the most important factor in the choice of a small gas turbine for military applications is its ability to develop more power, per unit weight and volume, than other engine types. In general, the specific weight of reciprocating engines, in the same power class as the subject gas turbine, average about 10–15 lb/hp with specific volumes ranging from 0.220 to 0.30 fr3/hp, compared to values of 0.53 lb/hp and 0.027 ft3/hp for the turbine. Over 20 different variations of this engine have been produced for such diverse applications as small aircraft and boat prime movers, aircraft and helicopter auxiliary power plants, mobile generator sets, and ‘winterization’ kits for U.S. Army field service. Intensive efforts are being made by companies on both sides of the Atlantic to develop the small gas turbine for a variety of applications. It seems reasonable to predict that these efforts will ultimately lead to the development of units with improved performance and lower initial cost.

Author(s):  
Luis Sanchez de Leon ◽  
Pavlos K. Zachos ◽  
Vassilios Pachidis

This paper presents a comparative assessment of different gas turbine open ‘dry’ cycle configurations as potential prime movers for marine commercial applications. The analyses will focus on optimising a three-spool gas turbine —featuring intercooling, reheating, and/or recuperation— for maximum thermal efficiency at design point, under the premise that targeted marine applications spend most of the time at cruising, hence part-load performance of the power plant will not play a huge role. The most promising configuration will be identified, and a whole methodology of systematic design-space exploration will be established, as the first necessary steps in the context of a much broader project, with the final aim of applying the same methodology to a wider range of candidate gas-turbine based power plants and performing multi-disciplinary optimisation of these candidates to fully assess the capabilities of the gas turbines to enter the market of the large cargo ships.


1983 ◽  
Vol 105 (4) ◽  
pp. 821-825 ◽  
Author(s):  
J. Wolf ◽  
S. Moskowitz

Studies of combined cycle electic power plants have shown that increasing the firing temperature and pressure ratio of the gas turbine can substantially improve the specific power output of the gas turbine as well as the combined cycle plant efficiency. Clearly this is a direction in which we can proceed to conserve the world’s dwindling petroleum fuel supplies. Furthermore, tomorrow’s gas turbines must do more than operate at higher temperature; they will likely face an aggressive hot gas stream created by the combustion of heavier oils or coal-derived liquid or gaseous fuels. Extensive tests have been performed on two rotating turbine rigs, each with a transpiration air cooled turbine operating in the 2600 to 3000°F (1427 to 1649°C) temperature range at increasing levels of gas stream particulates and alkali metal salts to simulate operation on coal-derived fuel. Transpiration air cooling was shown to be effective in maintaining acceptable metal temperatures, and there was no evidence of corrosion, erosion, or deposition. The rate of transpiration skin cooling flow capacity exhibited a minor loss in the initial exposure to the particulate laden gas stream of less than 100 hours, but the flow reduction was commensurate with that produced by normal oxidation of the skin material at the operating temperatures of 1350°F (732°C). The data on skin permeability loss from both cascade and engine tests compared favorably with laboratory furnace oxidation skin specimens. To date, over 10,000 hr of furnace exposure has been conducted. Extrapolation of the data to 50,000 hr indicates the flow capacity loss would produce an acceptable 50°F (10°C) increase in skin operating temperature.


Author(s):  
Anup Singh

In the 1970s, power generation from gas turbines was minimal. Gas turbines in those days were run on fuel oil, since there was a so-called “natural gas shortage”. The U.S. Fuel Use Act of 1978 essentially disallowed the use of natural gas for power generation. Hence there was no incentive on the part of gas turbine manufacturers to invest in the development of gas turbine technology. There were many regulatory developments in the 1980s and 1990s, which led to the rapid growth in power generation from gas turbines. These developments included Public Utility Regulatory Policy Act of 1978 (encouraging cogeneration), FERC Order 636 (deregulating natural gas industry), Energy Policy Act of 1992 (creating EWGs and IPPs) and FERC Order 888 (open access to electrical transmission system). There was also a backlash from excessive electric rates due to high capital recovery of nuclear and coal-fired plant costs caused by tremendous cost increase resulting from tightening NRC requirements for nuclear plants and significant SO2/NOx/other emissions controls required for coal-fired plants. During this period, rapid technology developments took place in the metallurgy, design, efficiency, and reliability of gas turbines. In addition, U.S. DOE contributed to these developments by encouraging research and development efforts in high temperature and high efficiency gas turbines. Today we are seeing a tremendous explosion of power generating facilities by electric utilities and Independent Power Producers (IPPs). A few years ago, Merchant Power (generation without power purchase agreements) was unheard of. Today it is growing at a very fast pace. Can this rapid growth be sustained? The paper will explore the factors that will play a significant role in the future growth of gas turbine-based power generation in the U.S. The paper will also discuss the methods and developments that could decrease the capital costs of gas turbine power plants resulting in the lowest cost generation compared to other power generation technologies.


2017 ◽  
Vol 139 (03) ◽  
pp. 76-77
Author(s):  
Lee S. Langston

This article explains research and development in the field of gas turbine power plants. Natural gas fueled gas turbines driving generators are proving to be the most versatile and effective energy converter in the engineer's arsenal of prime movers. Continued research and development are making these gas turbine power plants even more effective, flexible, and efficient. Gas turbine plants can operate under either base load operations or in quick start/fast shutdown modes. The reliable and dispatchable backup capacity of fast-reacting fossil technology to hedge against variability of electrical supply was a key to successful renewable use in the 26 countries studied. The article concludes that the use of versatile electric power gas turbines fueled by natural gas will continue to grow in the world. In the United States, with recent shale discoveries and fracking of natural gas, such use should increase, with or without the emphasis on renewables.


2016 ◽  
Vol 138 (06) ◽  
pp. 38-43
Author(s):  
Lee S. Langston

This article discusses various fields where gas turbines can play a vital role. Building engines for commercial jetliners is the largest market segment for the gas turbine industry; however, it is far from being the only one. One 2015 military gas turbine program of note was the announcement of an U.S. Air Force competition for an innovative design of a small turbine engine, suitable for a medium-size drone aircraft. The electrical power gas turbine market experienced a sharp boom and bust from 2000 to 2002 because of the deregulation of many electric utilities. Since then, however, the electric power gas turbine market has shown a steady increase, right up to present times. Coal-fired plants now supply less than 5 percent of the electrical load, having been largely replaced by new natural gas-fired gas turbine power plants. Working in tandem with renewable energy power facilities, the new fleet of gas turbines is expected to provide reliable, on-demand electrical power at a reasonable cost.


Author(s):  
Dieter Bohn ◽  
Nathalie Po¨ppe ◽  
Joachim Lepers

The present paper reports a detailed technological assessment of two concepts of integrated micro gas turbine and high temperature (SOFC) fuel cell systems. The first concept is the coupling of micro gas turbines and fuel cells with heat exchangers, maximising availability of each component by the option for easy stand-alone operation. The second concept considers a direct coupling of both components and a pressurised operation of the fuel cell, yielding additional efficiency augmentation. Based on state-of-the-art technology of micro gas turbines and solid oxide fuel cells, the paper analyses effects of advanced cycle parameters based on future material improvements on the performance of 300–400 kW combined micro gas turbine and fuel cell power plants. Results show a major potential for future increase of net efficiencies of such power plants utilising advanced materials yet to be developed. For small sized plants under consideration, potential net efficiencies around 70% were determined. This implies possible power-to-heat-ratios around 9.1 being a basis for efficient utilisation of this technology in decentralised CHP applications.


Author(s):  
Daniel E. Caguiat

The Naval Surface Warfare Center, Carderock Division (NSWCCD) Gas Turbine Emerging Technologies Code 9334 was tasked by NSWCCD Shipboard Energy Office Code 859 to research and evaluate fouling resistant compressor coatings for Rolls Royce Allison 501-K Series gas turbines. The objective of these tests was to investigate the feasibility of reducing the rate of compressor fouling degradation and associated rate of specific fuel consumption (SFC) increase through the application of anti-fouling coatings. Code 9334 conducted a market investigation and selected coatings that best fit the test objective. The coatings selected were Sermalon for compressor stages 1 and 2 and Sermaflow S4000 for the remaining 12 compressor stages. Both coatings are manufactured by Sermatech International, are intended to substantially decrease blade surface roughness, have inert top layers, and contain an anti-corrosive aluminum-ceramic base coat. Sermalon contains a Polytetrafluoroethylene (PTFE) topcoat, a substance similar to Teflon, for added fouling resistance. Tests were conducted at the Philadelphia Land Based Engineering Site (LBES). Testing was first performed on the existing LBES 501-K17 gas turbine, which had a non-coated compressor. The compressor was then replaced by a coated compressor and the test was repeated. The test plan consisted of injecting a known amount of salt solution into the gas turbine inlet while gathering compressor performance degradation and fuel economy data for 0, 500, 1000, and 1250 KW generator load levels. This method facilitated a direct comparison of compressor degradation trends for the coated and non-coated compressors operating with the same turbine section, thereby reducing the number of variables involved. The collected data for turbine inlet, temperature, compressor efficiency, and fuel consumption were plotted as a percentage of the baseline conditions for each compressor. The results of each plot show a decrease in the rates of compressor degradation and SFC increase for the coated compressor compared to the non-coated compressor. Overall test results show that it is feasible to utilize anti-fouling compressor coatings to reduce the rate of specific fuel consumption increase associated with compressor performance degradation.


Author(s):  
George M. Koutsothanasis ◽  
Anestis I. Kalfas ◽  
Georgios Doulgeris

This paper presents the benefits of the more electric vessels powered by hybrid engines and investigates the suitability of a particular prime-mover for a specific ship type using a simulation environment which can approach the actual operating conditions. The performance of a mega yacht (70m), powered by two 4.5MW recuperated gas turbines is examined in different voyage scenarios. The analysis is accomplished for a variety of weather and hull fouling conditions using a marine gas turbine performance software which is constituted by six modules based on analytical methods. In the present study, the marine simulation model is used to predict the fuel consumption and emission levels for various conditions of sea state, ambient and sea temperatures and hull fouling profiles. In addition, using the aforementioned parameters, the variation of engine and propeller efficiency can be estimated. Finally, the software is coupled to a creep life prediction tool, able to calculate the consumption of creep life of the high pressure turbine blading for the predefined missions. The results of the performance analysis show that a mega yacht powered by gas turbines can have comparable fuel consumption with the same vessel powered by high speed Diesel engines in the range of 10MW. In such Integrated Full Electric Propulsion (IFEP) environment the gas turbine provides a comprehensive candidate as a prime mover, mainly due to its compactness being highly valued in such application and its eco-friendly operation. The simulation of different voyage cases shows that cleaning the hull of the vessel, the fuel consumption reduces up to 16%. The benefit of the clean hull becomes even greater when adverse weather condition is considered. Additionally, the specific mega yacht when powered by two 4.2MW Diesel engines has a cruising speed of 15 knots with an average fuel consumption of 10.5 [tonne/day]. The same ship powered by two 4.5MW gas turbines has a cruising speed of 22 knots which means that a journey can be completed 31.8% faster, which reduces impressively the total steaming time. However the gas turbine powered yacht consumes 9 [tonne/day] more fuel. Considering the above, Gas Turbine looks to be the only solution which fulfills the next generation sophisticated high powered ship engine requirements.


Author(s):  
Christian Felsmann ◽  
Uwe Gampe ◽  
Manfred Freimark

Solar hybrid gas turbine technology has the potential to increase the efficiency of future solar thermal power plants by utilizing solar heat at a much higher temperature level than state of the art plants based on steam turbine cycles. In a previous paper the authors pointed out, that further development steps are required for example in the field of component development and in the investigation of the system dynamics to realize a mature technology for commercial application [1]. In this paper new findings on system dynamics are presented based on the simulation model of a solar hybrid gas turbine with parallel arrangement of the combustion chamber and solar receivers. The operational behavior of the system is described by means of two different scenarios. The System operation in a stand-alone electrical supply network is investigated in the first scenario. Here it is shown that fast load changes in the network lead to a higher shaft speed deviation of the electric generator compared to pure fossil fired systems. In the second scenario a generator load rejection, as a worst case, is analyzed. The results make clear that additional relief concepts like blow-off valves are necessary as the standard gas turbine protection does not meet the specific requirements of the solar hybrid operation. In general the results show, that the solar hybrid operational modes are much more challenging for the gas turbines control and safety system compared to pure fossil fired plants due to the increased volumetric storage capacity of the system.


1995 ◽  
Vol 117 (2) ◽  
pp. 245-250 ◽  
Author(s):  
K. Nakakado ◽  
T. Machida ◽  
H. Miyata ◽  
T. Hisamatsu ◽  
N. Mori ◽  
...  

Employing ceramic materials for the critical components of industrial gas turbines is anticipated to improve the thermal efficiency of power plants. We developed a first-stage stator vane for a 1300°C class, 20-MW industrial gas turbine. This stator vane has a hybrid ceramic/metal structure, to increase the strength reliability of brittle ceramic parts, and to reduce the amount of cooling air needed for metal parts as well. The strength design results of a ceramic main part are described. Strength reliability evaluation results are also provided based on a cascade test using combustion gas under actual gas turbine running conditions.


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