scholarly journals Influence of Early and Late Fuel Injection on Air Flow Structure and Kinetic Energy in an Optical SIDI Engine

2018 ◽  
Author(s):  
Hao Chen ◽  
Hanyang Zhuang ◽  
David L. Reuss ◽  
Volker Sick
Keyword(s):  
Kinetic Energy ◽  
Flow Structure ◽  
Fuel Injection ◽  
Air Flow

scholarly journals Improving the efficiency of carousel wind turbine using aerodynamic shield

2021 ◽  
Vol 2119 (1) ◽  
pp. 012093
Author(s):  
A F Serov ◽  
V N Mamonov ◽  
A D Nazarov ◽  
N B Miskiv
Keyword(s):  
Kinetic Energy ◽  
Flow Velocity ◽  
Air Flow ◽  
Cylindrical Body ◽  
Vertical Axis ◽  
Rotor Blades ◽  
Heat Generator ◽  
Axis Of Rotation ◽  
Wheel Torque ◽  
Air Flow Velocity

Abstract The problem of increasing the efficiency of using the oncoming air flow for a wind wheel with a vertical axis of rotation, which is a mechanical drive of the wind heat generator, is considered. It is proposed to increase the efficiency of the device by installing an aerodynamic shield for the air flow oncoming the wind wheel. Such a shield is a cylindrical body in which a heat generator is placed. The shield creates an effect of confuser, leading to an increase in the speed and, consequently, in the kinetic energy of the air flow acting on the rotor blades. It is shown experimentally that the presence of an aerodynamic shield under the conditions of the experiments carried out at an incoming air flow velocity of ~ 1 m/s leads to a practical doubling of the wind wheel torque.

scholarly journals Pulsating Flow Characteristics of Hot-Wire Air Flow Meter for Gasoline Fuel-Injection System.

1993 ◽  
Vol 59 (559) ◽  
pp. 935-940
Author(s):  
Yoshishige Ohyama ◽  
Khotarou Hirasawa ◽  
Yutaka Nishimura ◽  
Minoru Ohsuga ◽  
Mamoru Fujieda
Keyword(s):  
Fuel Injection ◽  
Air Flow ◽  
Flow Characteristics ◽  
Pulsating Flow ◽  
Injection System ◽  
Fuel Injection System ◽  
Hot Wire ◽  
Flow Meter

Flow Structure and Turbulence in the Tip Region of a Turbomachine Rotor Blade

2007 ◽  
Author(s):  
Francesco Soranna ◽  
Yi-Chih Chow ◽  
Oguz Uzol ◽  
Joseph Katz
Keyword(s):  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Flow Structure ◽  
Turbulent Diffusion ◽  
Rotor Blade ◽  
Trailing Edge ◽  
Left Hand ◽  
Tip Leakage ◽  
The Subject ◽  
Turbulence Production

The flow structure and turbulence in the tip region of a rotor blade operating downstream of a row of Inlet Guide Vanes (IGVs) are investigated experimentally in a refractive index matched facility that provides unobstructed view of the entire flow field. Stereo-PIV measurements are performed in closely spaced radial planes near the blade tip in a region extending from (slightly upstream of) the blade trailing edge to about 40% of the chord downstream of it. The data enable calculations of all the components of the phase-averaged velocity and vorticity vectors, as well as the strain rate, Reynolds stress, and turbulent diffusion tensors. Each rotor blade is confined between two tip-leakage vortices, a right hand vortex (RHV), generated by the subject blade and propagating along its right hand side, and a left hand vortex (LHV), generated by the previous blade in the same row and propagating along the left hand side of the subject blade. In addition, a trailing edge vortex (TEV) lays underneath the LHV and is subject to intense shearing/deformation by the LHV. RHV-induced radial gradients of radial phase-averaged velocity cause negative turbulence production, P, along the RHV-axis, and formation of a region of low P in the gap between the RHV and the blade suction surface. Trends of turbulent kinetic energy k and P within the RHV do not agree due to the effects of advection by the phase-averaged flow. To the left of the blade, shearing of the TEV by the LHV enhances turbulence production in the region between the two vortices and the rotor wake. Trends of turbulent kinetic energy and its production rate are in good agreement and peaks of k and P occur at the same location. As the TEV migrates away from the LHV, shearing effects become weaker and the dominant contributors to production are terms containing vortex-induced radial gradients of axial and radial velocities. Turbulent diffusion is a minor contributor to the evolution of turbulent kinetic energy in the tip region. It is also shown that the tip-leakage flow/vortex deteriorates the rotor blade performance, causing a ∼66% increase in shaft power input (per unit mass flow-rate) in the tip region in comparison with midspan.

Flame Holding in the Premixing Zone of a Gas Turbine Model Combustor After Forced Ignition of H2-NG-Air-Mixtures

2016 ◽  
Author(s):  
Matthias Utschick ◽  
Thomas Sattelmayer
Keyword(s):  
Gas Turbine ◽  
Atmospheric Pressure ◽  
Gas Turbines ◽  
Fuel Injection ◽  
Air Flow ◽  
Fuel Injector ◽  
Safe Operation ◽  
Trailing Edge ◽  
Damage And Failure ◽  
Turbine Model

Flashback and self-ignition in the premixing zone of typical gas turbine swirl combustors in lean premixed operation are immanent risks and can lead to damage and failure of components. Thus, steady combustion in the premixing zone must be avoided under all circumstances. This study experimentally investigates the flame holding propensity of fuel injectors in the swirler of a gas turbine model combustor with premixing of H2-NG-air-mixtures under atmospheric pressure and proposes a model to predict the limit for safe operation. The A2EV swirler concept exhibits a hollow, thick walled conical structure with four tangential slots. Four fuel injector geometries were tested. One of them injects the fuel orthogonal to the air flow in the slots (jet-in-crossflow-injector, JICI). Three injector types introduce the fuel almost isokinetic to the air flow at the trailing edge of the swirler slots (trailing edge injector, TEI). A cylindrical duct and a window in the swirler made of quartz glass allow the application of optical diagnostics (OH* chemiluminescence and Planar Laser Induced Fluorescence of the OH radical (OH-PLIF)) inside the swirler. The fuel-air-mixture was ignited with a focused single laser pulse during steady operation. The position of ignition was located inside the swirler in proximity to a fuel injection hole. If the flame was washed out of the premixing zone not later than four seconds after the ignition the operation point was defined as safe. Operation points were investigated at three air mass flows, three air ratios, two air preheat temperatures (573 K, 673 K) and 40 to 100 percent per volume hydrogen in the fuel composed of hydrogen and natural gas. The determined safety limit for atmospheric pressure yields a similarity rule based on a critical Damköhler number. Application of the proposed rule at conditions typical for gas turbines leads to these safety limits for the A2EV burner: With the TEIs the swirler can safely operate with up to 80 percent per volume hydrogen content in the fuel at an air ratio of two. With the JIC injector safe operation at stoichiometric conditions and 95 percent per volume hydrogen is possible.

Characterization and Control of Lean Blowout Using Periodically Generated Flame Balls

2006 ◽  
Author(s):  
Peter Albrecht ◽  
Frank Bauermeister ◽  
Mirko Bothien ◽  
Arnaud Lacarelle ◽  
Jonas Moeck ◽  
...  
Keyword(s):  
Flow Rate ◽  
Gas Turbines ◽  
Fuel Injection ◽  
Air Flow ◽  
Spark Discharge ◽  
Discharge System ◽  
Thermoacoustic Instabilities ◽  
Lean Blowout ◽  
Pilot Fuel ◽  
Industrial Gas Turbines

Combustion near LBO involves the complex physical processes including turbulence, air/fuel mixing, and chemical kinetics. The goal of this paper was to identify the typical combustion behaviour near LBO of the burner and to develop an effective actuator that will have the necessary control authority without having adverse effects such as increased emissions. Early detection and effective extension of lean blowout (LBO) are the keys to ensure flight safety and low emissions for aero engines, and are of importance to industrial gas turbines for operation below regulated NOx limits. In addition, efficient actuation are crucial for effective active LBO control. An experimental investigation of LBO was carried out using a swirl-stabilized atmospheric combustor with separate pilot and premix gaseous fuel (natural gas) injection systems. Systematic tests were performed including measurements of pressure, OH chemiluminescence and emissions for different combustor lengths, fuel split ratios, preheat temperatures and air flow rates. Operation near LBO may involve excitation of undesired thermoacoustic instabilities that have to be mitigated. LBO was approached by reducing the fuel flow rate while keeping the air flow rate, the preheat temperature and the other parameters constant. Control of the LBO and thermoacoustic instabilities was achieved by generating periodic flame balls. The LBO could be extended by 13 % relative to the natural lean blowout limit at nearly 50% reduced NO emission in comparison to common pilot fuel modulation. A spark discharge system was installed at the pilot fuel injection location. The periodic spark discharge was synchronized with the pulsed fuel injection at a phase shift of 165° and an operating frequency of 22 Hz to produce flame balls that affected the main combustion region. The flame balls excitation provided an effective tool for controlling the premix combustion characteristics at the LBO.

scholarly journals The air-flow structure and gas dispersion behavior in gas tunnel construction through bench cut method

2019 ◽  
Vol 23 (3 Part A) ◽  
pp. 1417-1424
Author(s):  
Rong Liu ◽  
Song Ren ◽  
Jinyang Fan ◽  
Fei Wu ◽  
Ngaha William
Keyword(s):  
Flow Structure ◽  
Air Flow ◽  
Gas Diffusion ◽  
Circulation Zone ◽  
Gas Dispersion ◽  
Diffusion Characteristics ◽  
Tunnel Section ◽  
Cut Method ◽  
Field Workers ◽  
Air Circulation

The inability to accurately predict the in rush of gas increases the fear of field workers security and unnecessary investments in tunnel ventilation. In this study, a 3-D numerical model was established to investigate the air-flow structure and gas diffusion characteristics of a gas tunnel during construction. The result showed that the flow inside the bottom bench mainly came from the re-circulation zone of the upper bench. Mutation in the tunnel section due to bottom bench excavation would cause the formation of some air circulation in the bottom bench. The circulation air in the bottom bench came from the re-circulation zone of the upper bench, while the air-flow in the considered zone was a polluted air. Based on the obtained results, there was no accumulation of CH4 inside the bottom bench. Nevertheless, gas gushing will still appear during the construction of the bottom bench surface, which can possibly lead to gas disaster. This study aims to provide some guidance for tunnel engineers on safety monitoring systems.

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