Ph.D. Thesis Proposal

Laminar Flame Speed Measurements at Elevated Temperatures and Pressures for Validation of Jet Fuel Mechanisms

Sampath Adusumilli

Montgomery Knight 317, May 4th 11:00 AM

Abstract

Conducting full-scale experiments on jet engines is a costly and time consuming process. A practical solution for avoiding these issues is to move towards full scale simulations of jet engines, as flow inside a jet engine is reacting, the reaction chemistry (which is dependent on the flow conditions, type of fuel and oxidizer etc.) plays an important role in the accuracy of the simulations. A full scale kinetic model for hydrocarbon combustion involves hundreds of species and thousands of reactions. Depending upon the flow conditions only some of the reactions are significant, this leads to a reduced order kinetic models. These kinetic models/mechanisms need to be validated before they can be used in simulations. Useful combustion characteristics for validation of these mechanisms against experimental data are ignition, extinction, speciation and flame structure. Representative data for each of these phenomena are often measured through ignition delay time, laminar flame extinction, species profiles from chemical reactors and laminar flame speed respectively. For this research, laminar flame speed (SL) is measured using a well-validated Bunsen Flame Technique (BFT) to experimentally validate chemical kinetic models.

Laminar flame speed is experimentally measured at conditions relevant to jet engine combustors and afterburners. n-decane, C2H4 and C3H6 are the representative jet fuels examined for this study. The conditions varied include high preheat temperatures (up to 650 K), high pressures (up to 5 atm) and vitiated conditions. Vitiation introduces combustion products such as CO2 and H2O into the reactant stream, this would alter chemical kinetics when compared to combustion in standard air. Diluents species in vitiated flow are generally divided into two categories reactive and non-reactive, CO2 and N2 are used as representative diluents respectively.

These measurements are used to assess the performance of several chemical kinetic models. Tools such as sensitivity analysis and reaction pathway analysis will be employed to derive conclusions about the performance of kinetic models. The validated kinetic models in conjunction with the experimental data will form the basis to define correlations of SL with change in diluent composition of a premixed mixture. Such correlations provide an empirical method to calculate SL at desired flow conditions.

Thesis Committee:

Dr. Jerry Seitzman (Advisor)                                      

Dr. Tim Lieuwen

Dr. Wenting Sun

Dr. Jechiel Jagoda