Research

Flame Stability and Dynamics of Advanced Next Generation Advance Propulsion Engines

High-speed air-breathing propulsion systems (Gas turbine engines, afterburners, ramjets and scramjets) relay on turbulent combustion for thrust generation. A turbulent flame stabilization mechanism is required to sustain a flame in the high velocity streams within these engines. Although this approach for flame stabilization is effective, combustion stability (static and dynamic) limits improvements in combustion efficiency and emission reduction due to flow field complexities. Furthermore, combustion instabilities are detrimental to efficiency and cause fatigue to system components. The research is focused on understanding the physical mechanisms influencing static and dynamic combustion stability to improve development of efficient combustion systems and reduce pollutant emissions (NOx, CO, soot).

Flame Extinction Physics-Based Model for Fuel Flexible Low-Emission Combustion

The research is formulated a physics-based model using key fundamental physical mechanisms for flame extinction. The novelty of the model is that it interactively couples the physics of the turbulent flow through a dynamic Lagrangian vortex element method and the strained flame reaction kinetics using a opposed-jet flame for the reaction kinetics. This novel modeling strategy would effectively capture the dynamic flame stability and extinction for turbulent premixed combustion resulting in the proliferation of innovative solutions for turbulent combustion-reliant systems for increased efficiency, broadened safe operating domain, and reduced emission of harmful pollutants.

Interaction Physics of Deflagrated Flame with Fluidic Flow for Pressure Gain Combustion

Pressure gain combustion, in the form of detonation, is an innovative scheme of turbulent combustion that increases combustion system efficiencies. The fundamental mechanism for achieving detonation is turbulent flame acceleration from deflagration-to-detonation. The process involves generation of high flow turbulence intensities and length scales for effective flame acceleration and propagation. The objective of the work is to investigate the fundamental physics of deflagrated flame dynamic interaction with the fluidic jet flow. The research will institute an understanding for the mechanisms of transient turbulent interaction structures, vortex dynamics, shear layer instabilities and jet instability modes.

Flow Physics and Vortex Instabilities of Jets in Crossflow

A jet in crossflow is a conventional approach for fluidic flow control. The research studies the fluidic-flow interaction and vortex dynamics in terms of temporal formation, evolution and instability for jets in crossflow. The research characterizes the jet interaction with the crossflow and investigates the fundamental mechanisms driving shear layer interaction and turbulent flow structures.

3D Tomographic Light-Field Imaging and Reconstruction of Flames

The objective of this study was to develop an advanced 3D tomographic optical diagnostic technique of flames. This was accomplished using light-field reconstruction of images taken of a premixed jet flame. This was accomplished using light-field reconstruction of images taken of a premixed jet flame. Development of a novel system for visualizing the intensity regions of flames will improve study combustion efficiency of flames. A model was developed for 3D tomographic imaging and used to investigate and characterize flames. The program makes use of high-speed photography to capture images of different angles of the flame and reconstruct the full flame from the information gathered.

Fluidic-Flow Interaction of Under-Expanded Microjets

The study investigates under-expanded microjets fluidic-flow coupling in terms of flow physics of the shearlayers interaction and Mach wave interference. The research characterizes the interaction modes based on spatial proximity of the microjets and cultivates scaling models for the interaction modes.

Aeromechanic Interactions and Propulsion

The research is investigating unsteady aeromechanic interactions and propulsion. Understanding unsteady aeromechanic interactions require time-resolved solutions and response to dynamic conditions to capture the flow physics. A Lagrangian element vortex model formulated using key flow physics is used in parallel to 4D-PIV to understand the dynamics of the flow interaction physics and separation.

Fluidic Thrust Augmentation for Unmanned Aerial Vehicles (UAVs)

The research explores fluidic-based augmentation for Unmanned Aerial Vehicles. A slot jet is used as the main driving mechanism for propulsion. This eliminates the acoustic and flow non uniformity of conventional fan-based propulsion. The study is focused on jet shear layer entrainment and confinement effects for optimal UAV propulsion performance.

Sharp Focus Multiple Light-Field System

The sharp focus system measures true quasi-planar two-dimensional visualizations of refractive disturbances using light-field function. It is superior to line-of-sight Schlieren and shadowgraph visualization. Furthermore, velocity field measurements are attained from particles (PIV) and reacting or nonreacting flow structures. The system is unique in that it provides PIV measurements at extreme sampling rates (>50kHz) relative to traditional PIV systems.