Benchmark test cases for the National Combustion Code

Chen, K.-H.; Norris, Andrew T.; Quealy, Angela; Liu, N.-S.

doi:10.2514/6.1998-3855

Cited by 18 publications

(7 citation statements)

References 8 publications

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“…The combination of these features is usually not available in other CFD codes and gives the NCC an advantage when computing recirculating, turbulent, reacting, spray flows. Previously, the NCC has undergone extensive validation studies for simple flows 14 , complex flows 15 , NO x emissions prediction performance 16 , and traditional gas turbine combustor/injectors 17 .…”

Section: The National Combustion Codementioning

confidence: 99%

NASA Numerical and Experimental Evaluation of UTRC Low Emissions Injector

Hicks

Tedder²,

Anderson³

et al. 2014

50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference

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Computational and experimental analyses of a PICS-Pilot-In-Can-Swirler technology injector, developed by United TechnologiesResearch Center (UTRC) are presented. NASA has defined technology targets for near term (called "N+1", circa 2015), midterm ("N+2", circa 2020) and far term ("N+3", circa 2030) that specify realistic emissions and fuel efficiency goals for commercial aircraft. This injector has potential for application in an engine to meet the Pratt & Whitney N+3 supersonic cycle goals, or the subsonic N+2 engine cycle goals. Experimental methods were employed to investigate supersonic cruise points as well as select points of the subsonic cycle engine; cruise, approach, and idle with a slightly elevated inlet pressure.Experiments at NASA employed gas analysis and a suite of laser-based measurement techniques to characterize the combustor flow downstream from the PICS dump plane. Optical diagnostics employed for this work included Planar Laser-Induced Fluorescence of fuel for injector spray pattern and Spontaneous Raman Spectroscopy for relative species concentration of fuel and CO 2 .The work reported here used unheated (liquid) Jet-A fuel for all fuel circuits and cycle conditions. The initial tests performed by UTRC used vaporized Jet-A to simulate the expected supersonic cruise condition, which anticipated using fuel as a heat sink.Using the National Combustion Code a PICS-based combustor was modeled with liquid fuel at the supersonic cruise condition. All CFD models used a cubic non-linear k-epsilon turbulence wall functions model, and a semi-detailed Jet-A kinetic mechanism based on a surrogate fuel mixture. Two initial spray droplet size distribution and spray cone conditions were used: 1) an initial condition (Lefebvre) with an assumed Rosin-Rammler distribution, and 7 degree Solid Spray Cone; and 2) the Boundary Layer Stripping (BLS) primary atomization model giving the spray size distribution and directional properties. Contour and line plots are shown in comparison with experimental data (where this data is available) for flow velocities, fuel, and temperature distribution. The CFD results are consistent with experimental observations for fuel distribution and vaporization.Analysis of gas sample results, using a previously-developed NASA NOx correlation, indicates that for sea-level takeoff, the PICS configuration is predicted to deliver an EINOx value of about 3 for the targeted supersonic aircraft. Emissions results at supersonic cruise conditions show potential for meeting the NASA goals with liquid fuel. NomenclatureAST = Advanced Subsonic Technology CFD = computational fluid dynamics CFL = Courant-Friedrichs-Lewy condition C p = specific heat CPU = central processing unit  = turbulent dissipation EINOX = emission index for oxides of nitrogen ERA = environmentally responsible aviation FAR = fuel-to-air ratio FWHM = full width at half maximum JST = Jameson-Schmidt-Turkel dissipation scheme k = turbulent kinetic energy LTO = landing-takeoff cycle  = molecular vibrational energy NCC = National...

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Section: The National Combustion Codementioning

confidence: 99%

NASA Numerical and Experimental Evaluation of UTRC Low Emissions Injector

Hicks

Tedder²,

Anderson³

et al. 2014

50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference

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“…[16][17][18][19][20][21][22]. Its target application is for low-emissions, fuel-flexible combustors, including the lean-direct-injection (LDI) combustors.…”

Section: Experimental and Computational Setupmentioning

confidence: 99%

On The TFNS Sub-Grid Models for Liquid-Fueled Turbulent Combustion

Liu

Wey²

2014

50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference

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This paper describes the time-filtered Navier-Stokes (TFNS) approach capable of capturing unsteady flow structures important for turbulent mixing in the combustion chamber and two different subgrid models used to emulate the major processes occurring in the turbulence-chemistry interaction. These two subgrid models are termed as LEM-like model and EUPDF-like model, respectively. Two-phase turbulent combustion in a singleelement lean-direct-injection (LDI) combustor is calculated by employing the TFNS/LEMlike approach as well as the TFNS/EUPDF-like approach. Results obtained from the TFNS approach employing these two different subgrid models are compared with each other, along with the experimental data, followed by more detailed comparison between the results of an updated calculation using the TFNS/LEM-like model and the experimental data. Acronym CFD= computational fluid dynamics DNS = direct numerical simulation LES = large-eddy simulation RANS = Reynolds-averaged Navier-Stokes approach URANS = unsteady RANS TFNS = time-filtered Navier-Stokes approach SGS = subgrid scale SFC = subfilter component FCP = filtering-control parameter LEM = linear-eddy mixing EUPDF = Eulerian probability density function LDI = lean-direct injection VBB = vortex-breakdown bubble PVC = precession vortex core IntroductionTogether with rig testing and diagnostics, combustion CFD is now a major tool for combustion technology development. It is being used to complement, and sometimes to substitute the rig test. This leads to reduced costs, deepened insight, and improved foresight. Nevertheless, high-fidelity simulation of liquid combustion in practical engineering devices remains an elusive target in spite of significant advances in combustion modeling and simulation over the past decade. The main difficulty lies in the fact that combustion operates at the intersection of fluid dynamics, fuel chemistry, and multi-phase physics. Consequently, in addition to high-fidelity models for turbulence, chemical kinetics, and liquid fuel atomization and transport, models for accurately accounting for their interactions also are required. Furthermore, these intricate physical and chemical phenomena are present throughout a broad range of time scales and length scales in engineering devices.Some of these modeling and simulation issues are discussed in the next section, followed by a description of the TFNS formulation for two-phase flow and the subfilter closure models in Section 3. In Section 4, we describe the estimation of the filtered, chemical-reaction source terms via two different subgrid models of turbulence-chemistry 1 Research Aerospace Engineer, Combustion Branch, Associate Fellow AIAA. 2 Research Aerospace Engineer, Combustion Branch, Member AIAA.

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“…The National Combustion Code (OpenNCC) [15,16] is an open-source Navier-Stokes flow solver tailored for advanced chemistry and unsteady modeling of reacting liquid spray. The solver uses a cell-centered finite-volume method for unstructured grids.…”

Section: High-fidelity Combustor Modelingmentioning

confidence: 99%

Parametric Modeling Investigation of a Radially-Staged Low-Emission Aviation Combustor

Heath

2016

54th AIAA Aerospace Sciences Meeting

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Aviation gas-turbine combustion demands high efficiency, wide operability and minimal trace gas emissions. Performance critical design parameters include injector geometry, combustor layout, fuel-air mixing and engine cycle conditions. The present investigation explores these factors and their impact on a radially staged low-emission aviation combustor sized for a next-generation 24,000-lbf-thrust engine. By coupling multi-fidelity computational tools, a design exploration was performed using a parameterized annular combustor sector at projected 100% takeoff power conditions. Design objectives included nitrogen oxide emission indices and overall combustor pressure loss. From the design space, an optimal configuration was selected and simulated at 7.1, 30 and 85% part-power operation, corresponding to landing-takeoff cycle idle, approach and climb segments. All results were obtained by solution of the steady-state Reynolds-averaged Navier-Stokes equations. Species concentrations were solved directly using a reduced 19-step reaction mechanism for Jet-A. Turbulence closure was obtained using a nonlinear κ-ε model. This research demonstrates revolutionary combustor design exploration enabled by multi-fidelity physics-based simulation. Nomenclature A 3 = inlet combustor cross sectional area, m 2

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Benchmark test cases for the National Combustion Code

Cited by 18 publications

References 8 publications

NASA Numerical and Experimental Evaluation of UTRC Low Emissions Injector

NASA Numerical and Experimental Evaluation of UTRC Low Emissions Injector

On The TFNS Sub-Grid Models for Liquid-Fueled Turbulent Combustion

Parametric Modeling Investigation of a Radially-Staged Low-Emission Aviation Combustor

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