Secondary air injection

About: Secondary air injection is a research topic. Over the lifetime, 11452 publications have been published within this topic receiving 112147 citations.

Increasing Flashback Resistance in Lean Premixed Swirl-Stabilized Hydrogen Combustion by Axial Air Injection

Abstract: Since lean premixed combustion allows for fuel-efficiency and low emissions, it is nowadays state of the art in stationary gas turbines. In the long term, it is also a promising approach for aero engines, when safety issues like lean blowout (LBO) and flame flashback in the premixer can be overcome. While for the use of hydrogen the LBO limits are extended, the flashback propensity is increased. Thus, axial air injection is applied in order to eliminate flashback in a swirl-stabilized combustor burning premixed hydrogen. Axial injection constitutes a non-swirling jet on the central axis of the radial swirl generator which influences the vortex breakdown position. In the present work changes in the flow field and their impact on flashback limits of a model combustor are evaluated. First, a parametric study is conducted under isothermal test conditions in a water tunnel employing particle image velocimetry (PIV). The varied parameters are the amount of axially injected air and swirl number. Subsequently, flashback safety is evaluated in the presence of axial air injection in an atmospheric combustor test rig and a stability map is recorded. The flame structure is measured using high-speed OH* chemiluminescence imaging. Simultaneous high-speed PIV measurements of the reacting flow provide insight in the time-resolved reacting flow field and indicate the flame location by evaluating the Mie scattering of the raw PIV images by the means of the Qualitative Light Sheet (QLS) technique.The isothermal tests identify the potential of axial air injection to overcome the axial velocity deficits at the nozzle outlet, which is considered crucial in order to provide flashback safety. This effect of axial air injection is shown to prevail in the presence of a flame. Generally, flashback safety is shown to benefit from an elevated amount of axial air injection and a lower swirl number. Note, that the latter also leads to increased NOx emissions, while axial air injection does not. Additionally, fuel momentum is indicated to positively influence flashback resistance, although based on a different mechanism, an explanation of which is suggested. In summary, flashback-proof operation of the burner with a high amount of axial air injection is achieved on the whole operating range of the test rig at inlet temperatures of 620 K and up to stoichiometric conditions while maintaining single digit NOx emissions below a flame temperature of 2000 K.Copyright © 2014 by ASME

Method for controlling fuel splits to gas turbine combustor

Abstract: A method for determining a target exhaust temperature for a gas turbine including: determining a target exhaust temperature based on a compressor pressure condition; determining a temperature adjustment to the target exhaust temperature based on at least one parameter of a group of parameters consisting of specific humidity, compressor inlet pressure loss and turbine exhaust back pressure; and adjusting the target exhaust temperature by applying the temperature adjustment.

Exhaust and intake rocker arm assemblies for modifying valve lift and timing during positive power

Abstract: The present invention is directed to an apparatus for operating at least one intake valve and at least one exhaust valve in an engine cylinder. The apparatus includes an exhaust valve operating assembly (510) for operating the at least one exhaust valve of the engine cylinder, wherein the exhaust valve operating assembly is capable of producing an exhaust gas recirculation event. The apparatus also includes an intake valve operating assembly (520) for operating the at least one intake valve of the engine cylinder. The apparatus further includes an exhaust modifying assembly for modifying the operation of the exhaust valve operating assembly during a predetermined engine operating condition and an intake modifying assembly for modifying the operation of the intake valve operating assembly during a predetermined engine operating condition.

Exhaust gas recirculation control apparatus for internal combustion engine

Abstract: In an internal combustion engine having an exhaust gas recirculation circuit, the efficiency of a turbocharger is raised in a wide engine rotational speed area and, even when a pressure in an intake circuit is higher than that in an exhaust circuit, an exhaust gas can be circulated. For this purpose, an openable intake throttle valve ( 12 e ) is provided on the more upstream side than an exhaust gas circulation position of the intake circuit ( 12 ), or a narrow portion ( 12 b ) is formed on the exhaust gas circulation position of the intake circuit and an intake bypass circuit ( 12 c ) for bypassing the narrow portion is provided. Further, an intake and exhaust bypass circuit ( 20 ) for connecting the intake circuit to the exhaust circuit ( 16 ) is provided. Then, the opening degree of the intake throttle valve or intake bypass circuit and the opening degree of the intake and exhaust bypass circuit are adjusted so as to set the pressure at the exhaust gas circulation position of the intake circuit to be lower than that in an exhaust manifold ( 16 a ).