Active Combustion Control by Fuel Forcing at Non-Coherent Frequencies

2007 ◽  
Author(s):  
Chukwueloka O. Umeh ◽  
Leonardo C. Kammer ◽  
Corneliu Barbu
Keyword(s):  
Gas Turbine ◽  
Pressure Fluctuations ◽  
Open Loop ◽  
Turbine Engines ◽  
Nox Emissions ◽  
Gas Turbine Engines ◽  
Combustion Control ◽  
Combustion Dynamics ◽  
Loop Control ◽  
Active Combustion Control

One impediment to substantially further the reductions in NOx emissions for aviation gas turbine engines is thermal-acoustic instabilities, also referred to as combustion dynamics. Dynamics arise due to the coupling of heat and pressure fluctuations in such systems. Numerous passive and semi-active control schemes, including performance de-rating and fuel staging, have been developed for land-based gas turbine engines. However, many of these schemes are not well suited to aviation engines, as a result of their weight and bulk. Observations of several combustors operating on either gaseous or liquid fuels show that the dominant dynamic frequencies have a special relation to specific non-coherent lower frequencies. Experiments show that combinations of two of these non-coherent frequencies form the dominant tones of the combustor. As part of NASA’s intelligent engines program, active combustion control is used to mitigate dynamics, as the combustor’s bulk fuel-air ratio (FAR) is made leaner in an effort to reduce NOx emissions by about 85% below the Committee on Aviation Environmental Protection (CAEP) 6 limit. In the feedback control scheme suggested in this paper, a small percentage of the overall fuel flow is pulsed at a given non-coherent frequency and with varying amplitude. The effectiveness of the dynamics reduction approach has been demonstrated via preliminary open loop control tests on a liquid-fuelled partially premixed high-pressure combustion test rig at GE Aviation in Evendale, Ohio.

Fuel Interchangeability for Lean Premixed Combustion in Gas Turbine Engines

2008 ◽  
Author(s):  
Don Ferguson ◽  
Geo. A. Richard ◽  
Doug Straub
Keyword(s):  
Natural Gas ◽  
Dynamic Response ◽  
Gas Turbine ◽  
Turbine Engines ◽  
Nox Emissions ◽  
Gas Turbine Engines ◽  
Lean Premixed Combustion ◽  
Combustion Dynamics ◽  
Rijke Tube ◽  
Fuel Blends

In response to environmental concerns of NOx emissions, gas turbine manufacturers have developed engines that operate under lean, pre-mixed fuel and air conditions. While this has proven to reduce NOx emissions by lowering peak flame temperatures, it is not without its limitations as engines utilizing this technology are more susceptible to combustion dynamics. Although dependent on a number of mechanisms, changes in fuel composition can alter the dynamic response of a given combustion system. This is of particular interest as increases in demand of domestic natural gas have fueled efforts to utilize alternatives such as coal derived syngas, imported liquefied natural gas and hydrogen or hydrogen augmented fuels. However, prior to changing the fuel supply end-users need to understand how their system will respond. A variety of historical parameters have been utilized to determine fuel interchangeability such as Wobbe and Weaver Indices, however these parameters were never optimized for today’s engines operating under lean pre-mixed combustion. This paper provides a discussion of currently available parameters to describe fuel interchangeability. Through the analysis of the dynamic response of a lab-scale Rijke tube combustor operating on various fuel blends, it is shown that commonly used indices are inadequate for describing combustion specific phenomena.

High Response Valve for Active Combustion Control

2001 ◽  
Author(s):  
Dong N. Wu ◽  
Joseph W. Michalski ◽  
Link C. Jaw ◽  
Kenneth Semega
Keyword(s):  
Gas Turbine ◽  
Piezoelectric Actuator ◽  
High Response ◽  
Turbine Engines ◽  
Bench Test ◽  
Gas Turbine Engines ◽  
Combustion Control ◽  
Flow Rates ◽  
Active Combustion Control ◽  
Modulation Control

This paper describes the development of a prototype high response fuel valve using piezoelectric actuator for fuel modulation control in gas turbine engines. In flow bench test, this prototype valve demonstrated 5∼11% peak-to-peak modulation strength at flow rates up to approximately 1500 pph and frequencies up to 500 Hz.

scholarly journals Active Combustion Control for aircraft gas turbine engines

2000 ◽  
Author(s):  
John DeLaat ◽  
Kevin Breisacher ◽  
Joseph Saus ◽  
Daniel Paxson
Keyword(s):  
Gas Turbine ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Combustion Control ◽  
Active Combustion Control

Design Study of an Advanced Concept Simple Gas Turbine for Possible Use in Low Emission Automobiles

1972 ◽  
Author(s):  
H. C. Eatock ◽  
M. D. Stoten
Keyword(s):  
High Pressure ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Pressure Ratio ◽  
Simple Cycle ◽  
Turbine Engines ◽  
Nox Emissions ◽  
Preliminary Design ◽  
Gas Turbine Engines ◽  
High Pressure Ratio

United Aircraft Corporation studied the potential costs of various possible gas turbine engines which might be used to reduce automobile exhaust emissions. As part of that study, United Aircraft of Canada undertook the preliminary design and performance analysis of high-pressure-ratio nonregenerated (simple cycle) gas turbine engines. For the first time, high levels of single-stage component efficiency are available extending from a pressure ratio less than 4 up to 10 or 12 to 1. As a result, the study showed that the simple-cycle engine may provide satisfactory running costs with significantly lower manufacturing costs and NOx emissions than a regenerated engine. In this paper some features of the preliminary design of both single-shaft and a free power turbine version of this engine are examined. The major component technology assumptions, in particular the high pressure ratio centrifugal compressor, employed for performance extrapolation are explained and compared with current technology. The potential low NOx emissions of the simple-cycle gas turbine compared to regenerative or recuperative gas turbines is discussed. Finally, some of the problems which might be encountered in using this totally different power plant for the conventional automobile are identified.

Model Predictive Control for Gas Turbine Engines

2018 ◽  
Author(s):  
Amit Pandey ◽  
Maurício de Oliveira ◽  
Robert H. Moroto
Keyword(s):  
Model Predictive Control ◽  
Gas Turbine ◽  
Predictive Control ◽  
Closed Loop ◽  
Open Loop ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Physical Constraints ◽  
Classical Control ◽  
Predictive Controllers

The use of Model Predictive Control (MPC) is commonplace in many industrial applications. The anticipative nature of MPC and the inclusion of physical constraints into the control framework presents many advantages over classical control strategies. Despite these advantages, obtaining an accurate open-loop model of the underlying process is often a difficult and time consuming process. In this paper, a methodology is introduced to identify linear open-loop models of gas turbine engines from closed-loop data. The closed-loop data can be obtained by any sufficiently informative experiment from a plant in operation or simulation. We present simulation results here. These open-loop models are then used in the design of model predictive controllers at a number of operating points of the turbine. The predictive controllers we designed include physical constraints on the fuel and air flow into the turbine. The performance of these predictive controllers is compared in simulation against existing classical control techniques in a number of typical operating scenarios including off loads, on loads and set point changes.

Combustor Design Trends for Aircraft Gas Turbine Engines

1996 ◽  
Author(s):  
G. J. Sturgess
Keyword(s):  
Gas Turbine ◽  
Considerable Importance ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Enabling Technology ◽  
Commercial Aircraft ◽  
Combustion Dynamics ◽  
Performance Trends ◽  
Air Mixing

Advanced performance trends are surveyed for possible future gas turbine engines to power several classes of military and commercial aircraft. The resulting combustor trends are enumerated. Examples of enabling technology are given. Combustion considerations are discussed, and many commonalities between applications are discovered; fuel/air mixing and combustion dynamics emerge as topics of considerable importance.

CFD Analysis of a Gas Turbine Engine Test Cell to Understand and Alleviate Infrasound

2015 ◽  
Author(s):  
John T. Pearson ◽  
Yogi Sheoran ◽  
Bill Schuster
Keyword(s):  
Gas Turbine ◽  
Structural Damage ◽  
Pressure Fluctuations ◽  
Test Cell ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Engine Test ◽  
Turbine Engine ◽  
Computational Fluid Dynamics Cfd ◽  
Pass Through

Gas turbine engines often pass through tests in enclosed test facilities. One problem that arises during these tests is the infrasound phenomenon. Infrasound can be a problem for many reasons, ranging from rattling windows to structural damage to the test cell. The aim of this paper is to understand the cause of severe infrasound experienced at Honeywell Aerospace and to evaluate and select a solution using advanced Computational Fluid Dynamics (CFD) techniques. These CFD simulations modeled an entire test cell with an engine in place, which is a more complete approach than what is reported in the literature. The DES turbulence model was applied in a transient, compressible, turbulent simulation in order to capture small pressure fluctuations. Test data taken using an engine/test cell configuration that does not cause problems was used to successfully validate the CFD approach. It was found that the narrow, high-velocity exhaust plume examined in this study impacted the convex blast plate in the aft portion of the test cell having diffused only slightly. The exhaust then rebounded and buffeted the plume, causing extreme dynamic loading. Through a modification to the blast basket, it was shown that the problem would be alleviated and sound pressure levels in the test cell would be reduced by 5 to 32 dB, depending on location in the test cell.

Development of a Fuel Air Premixer for Aero-Derivative Dry Low Emissions Combustors

1994 ◽  
Author(s):  
Narendra D. Joshi ◽  
Michael J. Epstein ◽  
Susan Durlak ◽  
Steven Marakovits ◽  
Paul E. Sabla
Keyword(s):  
Gas Turbine ◽  
Operating Conditions ◽  
Experimental Program ◽  
Design Parameters ◽  
Turbine Engines ◽  
Nox Emissions ◽  
Gas Turbine Engines ◽  
Single Digit ◽  
Test Conditions ◽  
Industrial Gas Turbine

An experimental program was conducted to develop premixer concepts for use in GE’s aero-derivative Marine and Industrial gas turbine engines such as the LM 1600, 2500 and 6000. These engines operate typically at pressure ratios up to 30:1. Extensive tests in 1 and 2 cup test combustors were carried out to evaluate the Double Annular Counter-Rotating Swirler (DACRS) premixers at test conditions representative of the above mentioned engines. These tests also help establish combustor design parameters. Single digit NOx emissions were measured at engine operating conditions with the DACRS II and III premixers. Premixer interactions and their effects on Lean Blow Out were also studied.

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