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Chelliah, Harsha

Harsha Chelliah

Primary Appointment

Mechanical and Aerospace Engineering

Contact Information

Telephone: 924-6037
Fax: 982-2037
Email: hkc3w@virginia.edu

Research Interests

Combustion

Research Description

Prof. Chelliah?s primary research interests are in the area of theoretical and experimental combustion, with emphasis on understanding the fundamental interactions between fluid dynamics and finite-rate chemistry. In the applied arena, he is focused on developing highly optimized combined heat and power systems using a range of renewable biofuels. A list of currently and recently funded research projects are described below: 1. Development of Reduced Kinetic Models (supported by AFOSR/NASA and previously by the Office of Secretary of Defense): Elementary reaction pathways that describe the pyrolysis and oxidation hydrocarbon fuels typically consist of 100?s of species in over 1000 reaction steps. The objective of this work is to derive systematically developed reduced reaction models for engineering applications based on characteristic physical time scales. In particular, efficient implementation of reduced reaction models in time dependent, multi-dimensional hypersonic reacting flow simulations is the key focus of this work, eg. two-dimensional supersonic shear layers as shown. Reduced reaction models developed to date include hydrogen-air, methane-air, ethylene-air, heptane-air, and JP10-air. 2. Development and Validation of Soot Kinetic Models (supported by Rolls Royce and State of Virginia): Combustors of mid-to-large size gas-turbine engines operate under high-pressure conditions, ranging from 25-50 atm. While modern gas-turbine engines have significantly reduced the formation of pollutants, very fine soot particles (10-100 nm) can still be formed in these engines. The objective of this project is to collect high-quality soot particle formation and oxidation data under more realistic high-pressure conditions to validate soot kinetic models. The models developed will be implemented and validated in several laboratory scale reacting flow configurations (tube reactors and counterflow flames ? see photo) and subsequently implemented in simulation of complex multi-dimensional reacting flow simulations. The chemical kinetic model development work will be carried out in close collaboration with the NIST Combustion and Kinetics Group. 3. Combined Heat and Power using Renewable Biomass (supported by Virginia State Dept. of Minerals, Mining, and Energy and Capstone Turbines): With the current energy cost, combined heat and power concept can yield an immediate impact on the energy cost of many industries. The objective of this project is to explore the utilization of renewable fuels derived from biomass in combined heat and power mode. Two Capstone Microturbines have been installed and tested at the decommissioned reactor building in grid connected mode, as as shown in the photograph. 4. Fire Suppression by Condensed Phase Agents and Search for Alternatives (supported by National Institute of Standards and Technology, Gaithersburg, MD and Boeing Corp.): The goal of this project was to understand the basic physical, thermal and chemical fire suppression mechanism for several gaseous and condensed-phase agents (i.e. solid or liquid agents). Both experimental and theoretical/computational approaches were employed. Experiments were performed using an enclosed counterflow burner with two opposed fuel and air streams. The condensed-phase fire suppressing agent was introduced with the air stream (see the photograph of a counterflow flame with sodium bicarbonate particles). The main advantage of this flow field was the ability to accurately simulate the two-phase reacting flow field and identify the rate controlling physical, thermal and chemical effects of fire suppressing agents. With the knowledge gained, effective replacements for the now banned halogenated fire suppressants are being pursued. 5. Combustion of Porous Graphite and Magnesium Particles Under Microgravity (previously supported by NASA Glenn Research Center, Cleveland, OH): The focus of this project is to develop a detailed model that takes into account the interaction between heterogeneous combustion of a porous char particle with the external homogeneous combustion. The heterogeneous model developed includes the transport and combustion within a porous particle, hence the model can effectively decouple the physical fluid dynamical effects from the intrinsic surface reaction rates. The supporting experiments to validate the model developed were performed using the NASA Reduced Gravity Aircraft (see the photograph). Simplified models developed based on this comprehensive study can be applied to simulation of porous coal particle combustion on earth as well as combustion of Mg particles in Martian atmospheric conditions.

Selected Publications

Rockwell RD, Goyne C P, Rice B , Chelliah H , McDaniel J C, Edwards... J , Development of a Premixed Combustion Capability for Scramjet Combustion Experiment, ; . () |

Esposito G , Sarnacki B G, Chelliah H K, Uncertainty propagation of chemical kinetics parameters and binary diffusion coefficients in predicting extinction limits of hydrogen/oxygen/nitrogen non-premixed flames, ; Combustion Theory and Modelling. 16(6) |

Sarnacki BG, G Esposito G , Krauss R H, Chelliah H K, Extinction limits and associated uncertainties of nonpremixed counterflow flames of methane, ethylene, propylene and n-butane in air, ; Combustion and Flame. 159(3) 1026-1043 |

Linteris Gregory T, Burgess Donald R, Takahashi Fumiaki , Katta Viswanath R, Chelliah Harsha K, Meier Oliver , Stirred reactor calculations to understand unwanted combustion enhancement by potential halon replacements, ; Combustion and Flame. 159(3) 1016-1025 |

Esposito G , Chelliah H K, Skeletal reaction models based on principal component analysis: Application to ethylene?air ignition, propagation, and extinction phenomena, ; Combustion and Flame . 158(3) 477-489 |

Linteris G T, Takahashi F, Katta V R, Chelliah H , Meier O , Thermodynamic analysis of suppressant-enhanced overpressure in the FAA Aerosol Can Simulator, ; Fire Safety Science. 10(1) 307-320 |

Laufer G, Lee AS, Chelliah HK, Multiphoton excitation ionization of N(2) following collisional energy transfer with H(2)O: a potential measure of molecular mixing., 1997; Applied optics. 36(15) 3278-87 PMID: 18253336 |