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Investigation of High Pressure Combustion and Emissions Characteristics of a Lean Direct Injection Combustor Concept

Ahmed, Abdelallah
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1471345597

Abstract Details

2016, MS, University of Cincinnati, Engineering and Applied Science: Aerospace Engineering.
The present work investigates emission characteristics and flame behavior of a Lean Direct Injection (LDI) combustor at elevated inlet air temperatures and pressures. The LDI consisted of a 9-point fuel injection system setup in a 3 by 3 array, where each point is made of a fuel nozzle fitted into a counter-rotating radial-radial swirler.To optimize flame anchoring and low NOx potential, two swirlers with varying intensities were used. Swirler #1 has a swirl number of 1.03 and is considered the high strength swirler. The larger recirculation zone created by this swirler is desirable for the increased turbulence and residence time, which will allow for more complete combustion and flame anchoring. Swirler #2 has a swirl number of 0.6, and is considered the low strength swirler. The higher axial velocities of this swirler allowed for a decreased residence time, which will lessen NOx production. To balance flame anchoring with lower NOx potential, 3 high strength swirlers were used in the central row of the array and 6 low strength swirlers were placed in the first and third row. To allow for a wide range of operating conditions, three fuel stages were employed with this combustor. The three stages consist of the pilot flame, which is the central cup operating solely, the 5 cup-staged flame, which is the central circuit operating with the 4 side circuit, and the 9 cup-staged flame, which is all active injection points. Three emission probes collected localized combustion byproducts, which were used to measure the molar fractions of nitric oxide, nitrogen dioxide, carbon monoxide, oxygen, and unburned hydrocarbons. Tests were undertaken with inlet air temperatures and pressures varying from 400°F (478-K) to 515°F (541-K) and 1-atm to 7-atm, respectively. Test results indicate that NOx formation is highly dependent on the fuel staging. The emission index of NOx (g-NOx/Kg-Fuel) were similar for just the central circuit lit (pilot) to all circuits lit (9-cup). For example, with 400°F inlet air temperature at 4atm, the EINOx for the pilot (φ=0.16), 5-cup (φ=0.35), and the 9-cup (φ=0.60) flames were 1.4 g/Kg, 1.35 g/Kg, and 1.56 g/Kg, respectively. However, the EINOx becomes exponentially proportional to the equivalence ratio when considering the three injection circuits independently. Correlations of the EINOx were developed for the three circuits with independent variables being equivalence ratio, inlet pressure and inlet air temperature. The experimental results indicate that this combustor generates NOx at similar rates as lean premixed combustors. However, the benefits of the LDI is its inherent ability of avoid unwarranted flashback and auto-ignition.
San-Mou Jeng, Ph.D. (Committee Chair)
Ahmed M. ElKady, Ph.D. (Committee Member)
Shaaban Abdallah, Ph.D. (Committee Member)
97 p.
Aerospace Materials
Lean Direct Injection; Low NOx; High Pressure Combustion; Aviation Combustion

Recommended Citations

Citations

  • Ahmed, A. (2016). Investigation of High Pressure Combustion and Emissions Characteristics of a Lean Direct Injection Combustor Concept [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1471345597

    APA Style (7th edition)

  • Ahmed, Abdelallah. Investigation of High Pressure Combustion and Emissions Characteristics of a Lean Direct Injection Combustor Concept. 2016. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1471345597.

    MLA Style (8th edition)

  • Ahmed, Abdelallah. "Investigation of High Pressure Combustion and Emissions Characteristics of a Lean Direct Injection Combustor Concept." Master's thesis, University of Cincinnati, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1471345597

    Chicago Manual of Style (17th edition)

ucin1471345597
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© 2016, all rights reserved.
This open access ETD is published by University of Cincinnati and OhioLINK.
Release 3.2.12