Design, Testing, and Performance Impact of Exhaust Diffusers in Aero-Derivative Gas Turbines for Mechanical Drive Applications

2019 ◽  
Author(s):  
Alberto Scotti Del Greco ◽  
Tomasz Jurek ◽  
Daniele Di Benedetto ◽  
Vittorio Michelassi ◽  
Giacomo Ragni ◽  
...  
Keyword(s):  
Gas Turbines ◽  
High Speed ◽  
Large Scale ◽  
Operating Conditions ◽  
Cycle Performance ◽  
Shaft Speed ◽  
Significant Drop ◽  
Electric Generator ◽  
Power Turbine ◽  
Inlet Conditions

Abstract The demand for gas-turbine (GT) based flexible power generation and mechanical drive is increasing due to the growing penetration of renewables and due to the need to quickly adjust production and operate at part load respectively. As efficiency operability low emissions, small footprint, availability and maintainability are of paramount importance, engine designers are leaning towards aircraft engine architectures that, with appropriate modifications mostly to the combustion system and turbine, can meet market needs. To leverage the large experience from aircraft propulsion, aero-derivative engines maintain the same architecture, with a high-speed shaft core, and a low-speed shaft driven by a multi-stage low-pressure turbine. While in aircraft engines power is adjusted by changing fuel rate and shaft speed, that go hand in hand, mechanical drive engines have more stringent needs that require changing the delivered power by keeping the shaft speed under control to guarantee the operation of the driven equipment (an LNG compressor or an electric generator). Therefore, the power turbine may deliver exit flow profiles and angles that put the turbine exhaust diffuser under severe off-design conditions, with the onset of large scale separations, large kinetic losses, and ultimately a significant drop on cycle performance. This paper describes Baker Hughes, a GE company experience in the CFD assisted design and scale-down testing of aero-derivative exhaust diffusers. The design incorporates the requirements of hot-end mechanical drive in multiple the power turbine operating conditions to determine the best compromise between peak design performance and off-design operability. The test in similitude conditions considered four relevant operating points. The inlet conditions matched with the power turbine exit profiles by the concerted action of swirl vanes and perforated plates, the design of which was heavily CFD assisted. Predictions matched measurements in terms of pressure recovery, kinetic losses, and exhaust velocity profiles. Different data post-processing and averaging were considered to properly factor in the diffuser losses into the overall turbine performance.

DESIGN, TESTING, AND PERFORMANCE IMPACT OF EXHAUST DIFFUSERS IN AERO-DERIVATIVE GAS TURBINES FOR MECHANICAL DRIVE APPLICATIONS

2020 ◽  
pp. 1-25
Author(s):  
Alberto Scotti del Greco ◽  
Vittorio Michelassi ◽  
Tomasz Jurek ◽  
Daniele Di Benedetto
Keyword(s):  
Gas Turbines ◽  
High Performance ◽  
Cycle Performance ◽  
Shaft Speed ◽  
Performance Impact ◽  
Electric Generator ◽  
Power Turbine ◽  
Fuel Rate ◽  
Scale Down ◽  
Inlet Conditions

Abstract The growing penetration of renewables calls for power generation and mechanical drive gas-turbine (GT) capable of quickly adjusting production and operate at part load. Aero-derivative engine architectures leverage the large experience from aircraft propulsion, have small footprint, high performance, availability and maintainability. Aircraft engines adjust power with fuel rate and shaft speed that go hand in hand. Mechanical drive engines need to change the delivered power by keeping the shaft speed under control to guarantee the operation of the driven equipment (an LNG compressor or an electric generator). Hence, the power turbine exhaust may deliver velocity and angle profiles that put the discharge diffuser in severe off-design with flow separations, high kinetic losses, and cycle performance shortfall. This paper describes Baker Hughes a GE company experience in the CFD assisted design and similitude scale-down testing of aero-derivative hot-end drive exhaust diffusers in multiple operating points. The diffuser inlet conditions reproduce power turbine exit profiles by using swirl vanes and perforated plates, the design of which is heavily CFD assisted. Predictions match measurements in terms of pressure recovery, kinetic losses, and exhaust velocity profiles. Different data post-processing and averaging are considered to properly factor in the diffuser losses into the overall turbine performance.

Gas Turbine Power Plant of Low Power GTP-10S

2020 ◽  
pp. 85-106
Author(s):  
Valentin Gusarov ◽  
Leonid Yuferev ◽  
Zahid Godzhaev ◽  
Aleksandr Parachnich
Keyword(s):  
Gas Turbines ◽  
High Speed ◽  
Permanent Magnets ◽  
Armed Forces ◽  
Electric Generator ◽  
Power Turbine ◽  
Thrust Vector ◽  
Small Engines ◽  
Heat Energy Recovery ◽  
Gas Turbine Power Plant

Currently, there is an increase in the use of gas turbines. Today they are used in the energy sector: aviation, armed forces, and the navy. The introduction of a new manufacturing technology developed by the authors will make it possible to manufacture cheap and reliable installations and thus ensure an exceptional position on the Russian market for goods and technologies, and taking into account the use of intellectual rights, abroad. The scientific novelty of the sample is the method of calculating small engines with a centrifugal compressor, a centripetal turbine and a combustion chamber with a negative thrust vector of the air flow. It is shown that the developed microgas turbine cogeneration power generator consists of a microturbine engine with a periphery, a free power turbine necessary for the selection of mechanical power, a high-speed electric generator with permanent magnets, an electronic power conversion system, exhaust heat energy recovery system and an automatic control system.

scholarly journals The Influence of Carrier Air Preheating on Autoignition of Inline-Injected Hydrogen–Nitrogen Mixtures in Vitiated Air of High Temperature

2017 ◽  
Vol 140 (3) ◽  
Author(s):  
Christoph A. Schmalhofer ◽  
Peter Griebel ◽  
Manfred Aigner
Keyword(s):  
Hydrogen Content ◽  
Gas Turbines ◽  
High Speed ◽  
Flame Stabilization ◽  
Operating Conditions ◽  
Promoting Effect ◽  
Experimental Conditions ◽  
Lean Premixed Combustion ◽  
Image Velocimetry ◽  
Fuel Mixtures

The use of highly reactive hydrogen-rich fuels in lean premixed combustion systems strongly affects the operability of stationary gas turbines (GT) resulting in higher autoignition and flashback risks. The present study investigates the autoignition behavior and ignition kernel evolution of hydrogen–nitrogen fuel mixtures in an inline co-flow injector configuration at relevant reheat combustor operating conditions. High-speed luminosity and particle image velocimetry (PIV) measurements in an optically accessible reheat combustor are employed. Autoignition and flame stabilization limits strongly depend on temperatures of vitiated air and carrier preheating. Higher hydrogen content significantly promotes the formation and development of different types of autoignition kernels: More autoignition kernels evolve with higher hydrogen content showing the promoting effect of equivalence ratio on local ignition events. Autoignition kernels develop downstream a certain distance from the injector, indicating the influence of ignition delay on kernel development. The development of autoignition kernels is linked to the shear layer development derived from global experimental conditions.

Investigation on Flat-Fan Spray Characterization in High-Speed Air Coflow for Gas Turbine Online Water Washing Application

2021 ◽  
Author(s):  
Kiran Kumar ◽  
Vasudev Chaudhari ◽  
Srikrishna Sahu ◽  
Ravindra G. Devi
Keyword(s):  
Droplet Size ◽  
Gas Turbines ◽  
High Speed ◽  
Numerical Models ◽  
Cone Angle ◽  
Operating Conditions ◽  
Spray Characteristics ◽  
Spray Cone ◽  
Water Washing ◽  
Spray Characterization

Abstract Fouling in compressor blades due to dirt deposition is a major issue in land-based gas turbines as it impedes the compressor performance and degrades the overall engine efficiency. The online water washing approach is an effective alternate for early-stage compressor blade cleaning and to optimize the time span between offline washing and peak availability. In such case, typically a series of flat-fan nozzles are used at the engine bell mouth to inject water sprays into the inflowing air. However, optimizing the injector operating conditions is not a straightforward task mainly due to the tradeoff between blade cleaning effectiveness and material erosion. In this context, the knowledge on spray characteristics prior to blade impingement play a vital role, and the experimental spray characterization is crucial not only to understand the basic process but also to validate numerical models and simulations. The present paper investigates spray characteristics in a single flat-fan nozzle operated in the presence of a coflowing air within a wind-tunnel. A parametric investigation is carried out using different air flow velocity in the tunnel and inlet water temperature, while the liquid flow rate was maintained constant. The spray cone angle and liquid breakup length are measured using back-lit photography. The high-speed shadowgraphy technique is used for capturing the droplet images downstream of the injector exit. The images are processed following depth-of-filed correction to measure droplet size distribution. Droplet velocity is measured by the particle tracking velocimetry (PTV) technique. As both droplet size and velocity are known, the cross-stream evolution of local droplet mass and momentum flux are obtained at different axial locations which form the basis for studying the effectiveness of the blade cleaning process due to droplet impingement on a coupon coated with foulant of known mass.

scholarly journals An Empirical Approach to the Preliminary Design of a Closed Cycle Gas Turbine

1998 ◽  
Author(s):  
R. P. op het Veld ◽  
J. P. van Buijtenen
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
High Speed ◽  
State Of The Art ◽  
Preliminary Design ◽  
Power Turbine ◽  
Helium Gas ◽  
Source State ◽  
High Temperature Reactor ◽  
The Cost

This paper investigates the layout and achievable efficiencies of rotating components of a Helium gas turbine. This is done by making a preliminary design of the compressor and turbine needed for the power conversion in a combined heat and power plant with a 40 MWth nuclear high temperature reactor as a heat source. State of the art efficiency values of air breathing gas turbines are used for the first calculations. The efficiency level is corrected by comparing various dimensionless data of the Helium turbomachine with an air gas turbine of similar dimensions. A single shaft configuration with a high speed axial turbine will give highest performance and simple construction. If a generator has to be driven at a conventional speed, a free power turbine configuration must be chosen. The choice of the configuration depends among others on the cost and availability of the asynchrone generator and frequency convertor.

Development and Evaluation of Silicon Nitride Components for Ceramic Gas Turbine

1998 ◽  
Author(s):  
Yasushi Hara ◽  
Katsura Matsubara ◽  
Ken-ichi Mizuno ◽  
Toru Shimamori ◽  
Hiro Yoshida
Keyword(s):  
Silicon Nitride ◽  
Gas Turbines ◽  
High Speed ◽  
Gas Flow ◽  
Impact Damage ◽  
Turbine Blades ◽  
Impact Testing ◽  
Particle Impact ◽  
Inlet Temperature ◽  
Power Turbine

NGK Spark Plug Co., Ltd. has been developing various silicon nitride materials, and the technology for fabricating components for ceramic gas turbines (CGT) using theses materials. We are supplying silicon nitride material components for the project to develop 300 kW class CGT for co-generation in Japan. EC-152 was developed for components that require high strength at high temperature, such as turbine blades and turbine nozzles. In order to adapt the increasing of the turbine inlet temperature (TIT) up to 1350 °C in accordance with the project goals, we developed two silicon nitride materials with further improved properties: ST-1 and ST-2. ST-1 has a higher strength than EC-152 and is suitable for first stage turbine blades and power turbine blades. ST-2 has higher oxidation resistance than EC-152 and is suitable for power turbine nozzles. On applying these silicon nitride ceramics to CGT engine, we evaluated various properties of silicon nitride materials considering the environment in CGT engine. Particle impact testing is one of those evaluations. Materials used in CGT engine are exposed in high speed gas flow, and impact damage of these materials is considered to be a concern. We tested ST-1 in the particle impact test. In this test, we observed fracture modes, and estimated the critical impact velocity. This paper summarizes the development of silicon nitride components, and the result of evaluations of these silicon nitride materials.

Characterisation of Waves and Ligaments in Films Close to an Aeroengine Ball Bearing

2019 ◽  
Author(s):  
Jee Loong Hee ◽  
Kathy Simmons ◽  
David Hann ◽  
Michael Walsh
Keyword(s):  
Flow Rate ◽  
High Speed ◽  
Ball Bearing ◽  
Capillary Waves ◽  
Operating Conditions ◽  
Research Centre ◽  
Shaft Speed ◽  
High Speed Imaging ◽  
Liquid Phases ◽  
Mass Transfers

Abstract Surface waves are observed in many situations including natural and engineering applications. Experiments conducted at the Gas Turbine and Transmissions Research Centre (G2TRC) used high speed imaging to observe multiscale wave structures close to an aeroengine ball bearing in a test rig. The dynamic behavior and scale of the waves indicate that these are shear-driven although highly influenced by gravity at low shaft speed. To understand the interactions between gas and liquid phases including momentum and mass transfers, characterization of the observed waves and ligaments was undertaken. Waves were studied at surfaces close to the ball bearing and ligaments were assessed near the cage. Characterization was in terms of frequency and wavelength as functions of speed, flow-rate, bearing axial load and gravity. The assessments confirmed the existence of gravity-capillary waves and capillary waves. Gravity-capillary waves were measured to have a longer mean wavelength on the co-current side of the bearing (gravity and shear acting together) compared to the counter-current side (gravity and shear opposing). Using a published definition of critical wavelength (λcrit), measured wavelengths at 3,000 rpm were 2.56λcrit on the co-current side compared to 1.86λcrit at the countercurrent location. As shaft speed increases, wavelength reduces with transition to capillary waves occurring at around 0.83λcrit. At shaft speeds beyond 5000 rpm, capillary waves were fully visible and the wavelength was obtained as 0.435λcrit. Flow-rate and load did not significantly influence wavelength. Wave frequency was found to be proportional to shaft speed. The gravity-capillary waves had frequencies within the range 13–25 Hz while capillary waves exhibited a frequency well beyond 100 Hz. The frequencies are highly fluctuating with no effect of load and flow rate observed. Ligaments were characterized using Weber number and Stability number. The number of ligaments increased with shaft speed. A correlation for ligament number based on operating conditions is proposed.

scholarly journals Experimental Study on the Skidding Damage of a Cylindrical Roller Bearing

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4075 ◽  
Author(s):  
Qing Zhang ◽  
Jun Luo ◽  
Xiang-yu Xie ◽  
Jin Xu ◽  
Zhen-huan Ye
Keyword(s):  
High Speed ◽  
Large Scale ◽  
Failure Modes ◽  
Roller Bearing ◽  
Weight Ratio ◽  
Operating Conditions ◽  
Roller Bearings ◽  
Light Load ◽  
Cylindrical Roller Bearing ◽  
Cylindrical Roller

As large-scale rotating machines develop toward high rotating speed and high power–weight ratio, skidding damage has become one of the major initial failure modes of cylindrical roller bearings. Therefore, understanding the skidding damage law is an effective way to ensure the safety of machines supported by cylindrical roller bearings. To realize the skidding damage, a high-speed rolling bearing test rig that can simulate the actual operating conditions of aviation bearings was used in this paper, and the skidding damage dynamic behaviors of cylindrical roller bearings were investigated. In addition, to ensure the accuracy of the obtained skidding damage mechanism, the cylindrical roller bearing was carefully inspected by microscopic analysis when the skidding damage occurred. Out results show that instantaneous increases in friction torque, vibration acceleration, and temperature are clearly observed when the skidding damage occurs in the cylindrical roller bearing. Furthermore, under the conditions of inadequate lubrication and light load, the critical speed of skidding damage is rather low. The major wear mechanisms of skidding damage include oxidation wear, abrasive wear, and delamination wear. The white layers are found locally in the inner ring and rollers under the actions of friction heat and shear force.

Effect of Mechanical Preloads on the Dynamic Performance of Gas Foil Bearings

2008 ◽  
Author(s):  
Tae Ho Kim ◽  
Luis San Andre´s
Keyword(s):  
Large Amplitude ◽  
High Speed ◽  
Low Cost ◽  
Dynamic Performance ◽  
Cycle Performance ◽  
High Power Density ◽  
Shaft Speed ◽  
Foil Bearings ◽  
Bearing Force ◽  
Good Agreement

Gas foil bearings (GFBs) enable efficient, reliable and maintenance free operation of high-power-density microturbomachinery (< 200 kW). High speed rotors supported on bump-type GFBs, however, are prone to show large-amplitude subsynchronous motions albeit reaching limit cycle performance. Presently, commercial GFBs are simply modified to introduce a mechanical preload that induces a hydrodynamic wedge to generate more load support and direct stiffnesses. Three metal shims inserted under the bump strip layers and in contact with the bearing housing create a multiple lobe clearance profile at a very low cost. Shaft speed coastdown measurements reveal the rotordynamic performance of a rotor supported on original GBFs and (modified) shimmed GFBs. The later GFBs determine a raise in the rotor-bearing system natural frequency, as expected, and also act to delay the onset speed of large-amplitude subsynchronous motions. Predictions of imbalance response implementing linearized bearing force coefficients are in good agreement with measured amplitudes of synchronous response for both GFB configurations, original and modified.

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