Experimental and Theoretical Studies of a Novel Venturi LPP Combustor

2000 ◽  
Author(s):  
Nils A. Røkke ◽  
Andrew J. W. Wilson
Keyword(s):  
Pressure Drop ◽  
Gas Turbine ◽  
Liquid Fuel ◽  
Gas Generator ◽  
Turbine Engine ◽  
Throat Region ◽  
Low Emission ◽  
Lean Premixed ◽  
Fuel Staging ◽  
Performance And Emissions

A new gas turbine engine using a unique layout patented in Norway has a low emission combustion system under development. The gas generator uses entirely radial rotating components and employs a dual entry LP radial compressor, a radial HP compressor and a radial HP turbine. The power turbine is of a two stage axial design, coupled to an epicyclical gear embedded in the exhaust duct. Several combustor concepts have been tested and evaluated during the development of the engine. The engine is targeted for marine, power generation and train propulsion. For the marine and train application liquid fuel operation is needed, thus the primary focus in the development has been for a lean premixed prevapourised system. An interesting concept utilising two venturi premixers has been studied intensively. By utilising venturi premixers the following advantages can be achieved: • Low overall pressure drop but high injector pressure drop and velocities in the mixing region (throat region) • High shear forces and drag imposed on the droplets enhancing droplet shedding and evaporation • Excellent emission behaviour at designated load conditions Although these advantages can benefit gas turbine low emission combustion the challenges in using venturi premixers are: • Venturis are susceptible to separation and thus flame stabilisation within the venturi which is detrimental • Inlet flow disturbances enhance the tendency for separation in the venturis and must be minimised Studies were launched to investigate a proposed combustor configuration. These studies included analytical studies, Computational Fluid Dynamics (CFD) calculations of isothermal and combusting flow inside the combustor together with rig tests at atmospheric, medium and full pressure. Finally engine tests within the full operating range were conducted with very favourable emission figures for Lean Premixed Prevapourised (LPP) operation. The system was capable of running at below 20 ppm Nox and CO, at elevated power for liquid fuel. Control of part load performance and emissions is by variable fuel staging of the two venturi stages. The paper highlights the features of the venturi combustor development and discusses the characteristics in terms of flow conditions and droplet motion, heat transfer, ignition delay time and emissions.

Experimental and Theoretical Studies of a Novel Venturi Lean Premixed Prevaporized (LPP) Combustor

2000 ◽  
Vol 123 (3) ◽  
pp. 567-573 ◽  
Author(s):  
N. A. Ro̸kke ◽  
A. J. W. Wilson
Keyword(s):  
Pressure Drop ◽  
Gas Turbine ◽  
Liquid Fuel ◽  
Flame Stabilization ◽  
Gas Generator ◽  
Throat Region ◽  
Low Emission ◽  
Lean Premixed ◽  
Fuel Staging ◽  
Performance And Emissions

A new gas turbine engine using a unique layout patented in Norway has a low-emission combustion system under development. The gas generator uses entirely radial rotating components and employs a dual entry LP radial compressor, a radial HP compressor, and a radial HP turbine. The power turbine is of a two-stage axial design, coupled to an epicyclical gear embedded in the exhaust duct. Several combustor concepts have been tested and evaluated during the development of the engine. The engine is targeted for marine, power generation, and train propulsion. For the marine and train application liquid fuel operation is needed, thus the primary focus in the development has been for a lean premixed prevapourised system. An interesting concept utilizing two venturi premixers has been studied intensively. By utilizing venturi premixers the following advantages can be achieved: (1) low overall pressure drop but high injector pressure drop and velocities in the mixing region (throat region), (2) high shear forces and drag imposed on the droplets enhancing droplet shedding and evaporation, and (3) excellent emission behavior at designated load conditions. Although these advantages can benefit gas turbine low-emission combustion, the challenges in using venturi premixers are: (1) venturis are susceptible to separation and thus flame stabilization within the venturi which is detrimental and (2) inlet flow disturbances enhance the tendency for separation in the venturis and must be minimized. Studies were launched to investigate a proposed combustor configuration. These studies included analytical studies, computational fluid dynamics (CFD) calculations of isothermal and combusting flow inside the combustor together with rig tests at atmospheric, medium, and full pressure. Finally, engine tests within the full operating range were conducted with very favorable emission figures for lean premixed prevaporized (LPP) operation. The system was capable of running at below 20 ppm NOx and CO, at elevated power for liquid fuel. Control of part load performance and emissions is by variable fuel staging of the two venturi stages. The paper highlights the features of the venturi combustor development and discusses the characteristics in terms of flow conditions and droplet motion, heat transfer, ignition delay time, and emissions.

The Effect of Liquid-Fuel Preparation on Gas Turbine Emissions

2006 ◽  
Author(s):  
Sosuke Nakamura ◽  
Vince McDonell ◽  
Scott Samuelsen
Keyword(s):  
Gas Turbine ◽  
Liquid Fuel ◽  
Cylindrical Tube ◽  
Spray Angle ◽  
Preparation Process ◽  
Fuel Injector ◽  
Secondary Importance ◽  
Turbine Engine ◽  
Performance And Emissions ◽  
Air Mixing

The emissions of liquid-fuel fired gas turbine engines are strongly affected by the fuel preparation process that includes atomization, evaporation and mixing. In the present paper, the effects of fuel atomization and evaporation on emissions from an industrial gas turbine engine were investigated. In the engine studied, the fuel injector consists of a co-axial plain jet airblast atomizer and a premixer, which consists of a cylindrical tube with four mixing holes and swirler slits. The goal of this device is to establish a fully vaporized, homogeneous fuel/air mixture for introduction into the combustion chamber and the reaction zone. In the present study, experiments were conducted at atmospheric pressure and room temperature as well as at actual engine conditions (0.34MPa, 740K) both with and without the premixer. Measurements included visualization, droplet size and velocity. By conducting tests with and without the premixing section, the effect of the mixing holes and swirler slit design on atomization and evaporation was isolated. The results were also compared with engine data and the relationship between premixer performance and emissions was evaluated. By comparing the results of tests over a range of pressures, the viability of two scaling methods was evaluated with the conclusion that spray angle correlates with fuel to atomizing air momentum ratio. For the injector studied, however, the conditions resulting in superior atomization and vaporization did not translate into superior emissions performance. This suggests that, while atomization and the evaporation of the fuel are important in the fuel preparation process, they are of secondary importance to the fuel/air mixing prior to, and in the early stages of the reaction, in governing emissions.

The Effect of Liquid-Fuel Preparation on Gas Turbine Emissions

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Sosuke Nakamura ◽  
Vince McDonell ◽  
Scott Samuelsen
Keyword(s):  
Gas Turbine ◽  
Liquid Fuel ◽  
Cylindrical Tube ◽  
Spray Angle ◽  
Preparation Process ◽  
Fuel Injector ◽  
Secondary Importance ◽  
Turbine Engine ◽  
Performance And Emissions ◽  
Air Mixing

The emissions of liquid-fuel fired gas turbine engines are strongly affected by the fuel preparation process that includes atomization, evaporation, and mixing. In the present paper, the effects of fuel atomization and evaporation on emissions from an industrial gas turbine engine were investigated. In the engine studied, the fuel injector consists of a coaxial plain jet airblast atomizer and a premixer which consists of a cylindrical tube with four mixing holes and swirler slits. The goal of this device is to establish a fully vaporized, homogeneous fuel/air mixture for introduction into the combustion chamber and the reaction zone. In the present study, experiments were conducted at atmospheric pressure and room temperature as well as at actual engine conditions (0.34MPa, 740K) both with and without the premixer. Measurements included visualization, droplet size, and velocity. By conducting tests with and without the premixing section, the effect of the mixing holes and swirler slit design on atomization and evaporation was isolated. The results were also compared with engine data and the relationship between premixer performance and emissions was evaluated. By comparing the results of tests over a range of pressures, the viability of two scaling methods was evaluated with the conclusion that spray angle correlates with fuel to atomizing air momentum ratio. For the injector studied, however, the conditions resulting in superior atomization and vaporization did not translate into superior emissions performance. This suggests that, while atomization and the evaporation of the fuel are important in the fuel preparation process, they are of secondary importance to the fuel/air mixing prior to, and in the early stages of the reaction in, governing emissions.

Development of Dry Low-NOx Combustor for 300 kW Class Gas Turbine Applied to Co-Generation Systems

2001 ◽  
Author(s):  
Yoichiro Ohkubo ◽  
Osamu Azegami ◽  
Hiroshi Sato ◽  
Yoshinori Idota ◽  
Shinichiro Higuchi
Keyword(s):  
Gas Turbine ◽  
Output Power ◽  
Combustion Efficiency ◽  
Gas Generator ◽  
Turbine Engine ◽  
Partial Load ◽  
Wide Range ◽  
Compressor Inlet ◽  
Endurance Testing ◽  
Turbine Speed

A 300 kWe class gas turbine which has a two-shaft and simple-cycle has been developed to apply to co-generation systems. The gas turbine engine is operated in the range of about 30% partial load to 100% load. The gas turbine combustor requires a wide range of stable operations and low NOx characteristics. A double staged lean premixed combustor, which has a primary combustion duct made of Si3N4 ceramics, was developed to meet NOx regulations of less than 80 ppm (corrected at 0% oxygen). The gas turbine with the combustor has demonstrated superior low-emission performance of around 40 ppm (corrected at 0% oxygen) of NOx, and more than 99.5% of combustion efficiency between 30% and 100% of engine load. Endurance testing has demonstrated stable high combustion performance over 3,000 hours in spite of a wide compressor inlet air temperature (CIT) range of 5 to 35 degree C.. While increasing the gas generator turbine speed, the flow rate of primary fuel was controlled to hold a constant equivalence ratio of around 0.5 in the CIT range of more than 15 C. The output power was also decreased while increasing the CIT, in order to keep a constant temperature at the turbine inlet. The NOx decreases in the CIT range of more than 15 C. On the other hand, the NOx increases in the CIT range of less than 15 C when the output power was kept a constant maximum power. As a result, NOx emission has a peak value of about 40 ppm at 15 C.

scholarly journals A Parametric Starting Study of an Axial-Centrifugal Gas Turbine Engine Using a One-Dimensional Dynamic Engine Model and Comparisons to Experimental Results: Part 1 — Model Development and Facility Description

1998 ◽  
Author(s):  
A. Karl Owen ◽  
Anne Daugherty ◽  
Doug Garrard ◽  
Howard C. Reynolds ◽  
Richard D. Wright
Keyword(s):  
Gas Turbine ◽  
Initial Conditions ◽  
Model Development ◽  
Ground Level ◽  
Gas Turbine Engine ◽  
Calibration Data ◽  
Gas Generator ◽  
Turbine Engine ◽  
One Dimensional ◽  
Engine Model

A generic one-dimensional gas turbine engine model, developed at the Arnold Engineering Development Center, has been configured to represent the gas generator of a General Electric axial-centrifugal gas turbine engine in the six kg/sec airflow class. The model was calibrated against experimental test results for a variety of initial conditions to insure that the model accurately represented the engine over the range of test conditions of interest. These conditions included both assisted (with a starter motor) and unassisted (altitude windmill) starts. The model was then exercised to study a variety of engine configuration modifications designed to improve its starting characteristics and thus quantify potential starting improvements for the next generation of gas turbine engines. This paper discusses the model development and describes the test facilities used to obtain the calibration data. The test matrix for the ground level testing is also presented. A companion paper presents the model calibration results and the results of the trade-off study.

Development of a Lean-Premixed Two-Stage Annular Combustor for Gas Turbine Engines

1994 ◽  
Author(s):  
Fred C. Bahlmann ◽  
B. Martien Visser
Keyword(s):  
Gas Turbine ◽  
Turbine Engines ◽  
Emission Characteristics ◽  
Gas Turbine Engines ◽  
Two Stage ◽  
Low Emission ◽  
Lean Premixed ◽  
Annular Combustor

The development, from concept to hardware of a lean-premixed two-stage combustor for small gas turbine engines is presented. This Annular Low Emission Combustor (ALEC) is based on a patent of R.J. Mowill. Emission characteristics of several prototypes of this combustor under a variety of conditions are presented. It is shown that ultra-low NOx levels (< 10 ppm) can be reached with satisfactory CO levels (< 50 ppm).

scholarly journals Rapid Liquid Fuel Mixing for Lean-Burning Combustors: Low-Power Performance

2001 ◽  
Vol 123 (3) ◽  
pp. 574-579 ◽  
Author(s):  
M. Y. Leong ◽  
C. S. Smugeresky ◽  
V. G. McDonell ◽  
G. S. Samuelsen
Keyword(s):  
Low Power ◽  
Gas Turbine ◽  
Liquid Fuel ◽  
Direct Injection ◽  
Fuel Injector ◽  
Power Performance ◽  
Lean Burn ◽  
Engine Operation ◽  
Turbine Engine ◽  
Lean Direct Injection

Designers of advanced gas turbine combustors are considering lean direct injection strategies to achieve low NOx emission levels. In the present study, the performance of a multipoint radial airblast fuel injector Lean Burn injector (LBI) is explored for various conditions that target low-power gas turbine engine operation. Reacting tests were conducted in a model can combustor at 4 and 6.6 atm, and at a dome air preheat temperature of 533 K, using Jet-A as the liquid fuel. Emissions measurements were made at equivalence ratios between 0.37 and 0.65. The pressure drop across the airblast injector holes was maintained at 3 and 7–8 percent. The results indicate that the LBI performance for the conditions considered is not sufficiently predicted by existing emissions correlations. In addition, NOx performance is impacted by atomizing air flows, suggesting that droplet size is critical even at the expense of penetration to the wall opposite the injector. The results provide a baseline from which to optimize the performance of the LBI for low-power operation.

Test Experience With Turbine-End Foil Bearing Equipped Gas Turbine Engines

1983 ◽  
Author(s):  
F. J. Suriano ◽  
R. D. Dayton ◽  
Fred G. Woessner
Keyword(s):  
Gas Turbine ◽  
Thermal Environment ◽  
Full Range ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Engine Test ◽  
Gas Generator ◽  
Turbine Engine ◽  
Foil Bearings ◽  
Foil Bearing

The Garrett Turbine Engine Company, a Division of the Garrett Corporation, authorized under Air Force Contract F33615-78-C-2044 and Navy Contract N00140-79-C-1294, has been conducting development work on the application of gas-lubricated hydrodynamic journal foil bearings to the turbine end of gas turbine engines. Program efforts are directed at providing the technology base necessary to utilize high-temperature foil bearings in future gas turbine engines. The main thrust of these programs was to incorporate the designed bearings, developed in test rigs, into test engines for evaluation of bearing and rotor system performance. The engine test programs included a full range of operational tests; engine thermal environment, endurance, start/stops, attitude, environmental temperatures and pressures, and simulated maneuver bearing loadings. An 88.9 mm (3.5-inch) diameter journal foil bearing, operating at 4063 RAD/SEC (38,800 rpm), has undergone test in a Garrett GTCP165 auxiliary power unit. A 44.4 mm (1.75-inch) diameter journal foil bearing, operating at 6545 RAD/SEC (62,500 rpm) has undergone test in the gas generator of the Garrett Model JFS190. This paper describes the engine test experience with these bearings.

scholarly journals Evaporation Characteristics of Spray in a Lean Premixed-Prevaporization Combustor for a 100 KW Automotive Ceramic Gas Turbine

1994 ◽  
Author(s):  
Youichlrou Ohkubo ◽  
Yoshinorl Idota ◽  
Yoshihiro Nomura
Keyword(s):  
Gas Turbine ◽  
Mass Fraction ◽  
Liquid Fuel ◽  
Three Dimensional ◽  
Flame Stabilization ◽  
Fuel Spray ◽  
Inlet Temperature ◽  
Lean Combustion ◽  
Swirl Chamber ◽  
Lean Premixed

Spray characteristics of liquid fuel air-assisted atomizers developed for a lean premixed-prevaporization combustor were evaluated under two kinds of conditions: in still air under non-evaporation conditions at atmospheric pressure and in a prevaporization-premixing tube under evaporation conditions with a running gas turbine. The non-evaporated mass fraction of fuel spray was measured using a phase Doppler particle analyzer in the prevaporization-premixing tube, in which the inlet temperature ranged from 873K to 1173K. The evaporation of the fuel spray in the tube is mainly controlled by its atomization and distribution. The NOx emission characteristics measured with a combustor test rig were evaluated with three-dimensional numerical simulations. A low non-evaporated mass fraction of less than 10% was effective in reducing the exhausted NOx from lean premixed-prevaporization combustion to about 1/6 times smaller than that from lean diffusion (spray) combustion. The flow patterns in the combustor are established by a swirl chamber in fuel-air preparation tube, and affect the flame stabilization of lean combustion.

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