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Numerical Analysis of Non-Reacting Flow in a Multi-nozzle Swirl Stabilized Lean Direct Injection Combustor

Giri, Ritangshu
http://orcid.org/0000-0003-4288-9285
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1447690568

Abstract Details

2015, MS, University of Cincinnati, Engineering and Applied Science: Aerospace Engineering.
A multipoint lean direct injection (MLDI) concept was introduced recently in non-premixed combustion to obtain both low NOx emissions and good combustion stability. In this concept a key feature is the injection of finely atomized fuel into high swirling airflow at the combustor dome that provides a homogenous, lean fuel-air mixture. In order to achieve fine atomization and mixing of fuel and air quickly and uniformly, a well designed swirler system is imperative. The present study aims to investigate non-reacting aerodynamic flow characteristics in one such swirl stabilized multiple lean direct injection (MLDI) nozzle system, using the capabilities of computational fluid dynamics (CFD). The fuel nozzles were designed and provided by United Technologies Aerospace Systems (UTAS). The commercial CFD solver Fluent (Ansys Inc, USA) is incorporated to solve the 3-D Navier-Stokes equations for different CFD numerical formulations and, hence simulate the turbulent swirling flowfield generally associated with such systems. Two separate studies were conducted. The first study analyzed the effect of swirl on a turbulent flowfield in a rectangular chamber with sudden expansion, where the complex nozzle system housing air swirlers and a fuel injector were replaced by simple cylindrical inlets. The second study investigated typical aerodynamic flow features associated with the actual system. The domain for conducting simulations were the entire geometry in both cases. First a trusted grid is developed by carrying out grid refinement analysis for both studies. Then a comparison of different Reynolds-Averaged Navier Stokes (RANS) turbulence model were carried out for both cases. The time averaged Particle Image Velocimetry (PIV) data was used as a basis of comparison and the model most closely matching those values was finalized for further numerical computations. Steady state was employed for both set of problems. For the first problem, different swirl intensities were incorporated at the cylindrical inlet to study the changing structure of flowfield. The second numerical analysis of the actual geometric model was further subdivided into two sections. The first section studied the flowfield changes in this complex model by incorporating different mass flow rates for the same nozzle spacing of S = 1.36d. The solution captures the essential flow features generally associated with a non-reacting swirling flowfield in a LDI combustor. The second section analyzed the change in flowfield structure when the spacing between nozzles were varied from 1.1d to 2.72d. A single nozzle case was also used as a basis for comparison. The results obtained were also compared to the available time averaged PIV data. The effect of inter-nozzle spacing result in flows, where the nozzles interact strongly to a case where nozzles do not interact atleast for most of the axial locations. Thus the results provide a useable CFD model for evaluation of this flowfield while highlighting their areas of uncertainty. In addition to that, they also provide useful prerequisites for conducting further reacting flow analysis for this particular design.
Ephraim Gutmark, Ph.D. D.Sc. (Committee Chair)
Shaaban Abdallah, Ph.D. (Committee Member)
Mark Turner, Sc.D. (Committee Member)
156 p.
Aerospace Materials
MLDI; Swirl stabilized nozzles; LRZ; CRZ; CTRZ; SWJ

Recommended Citations

Citations

  • Giri, R. (2015). Numerical Analysis of Non-Reacting Flow in a Multi-nozzle Swirl Stabilized Lean Direct Injection Combustor [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1447690568

    APA Style (7th edition)

  • Giri, Ritangshu. Numerical Analysis of Non-Reacting Flow in a Multi-nozzle Swirl Stabilized Lean Direct Injection Combustor. 2015. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1447690568.

    MLA Style (8th edition)

  • Giri, Ritangshu. "Numerical Analysis of Non-Reacting Flow in a Multi-nozzle Swirl Stabilized Lean Direct Injection Combustor." Master's thesis, University of Cincinnati, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1447690568

    Chicago Manual of Style (17th edition)

ucin1447690568
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This open access ETD is published by University of Cincinnati and OhioLINK.