Department of Mechanical Engineering

Research

John W. Daily

Professor Daily and his reserach group use a variety of experimental, analytical and computational tools to study problems mainly related to energy and propulsion. Advanced experimental tools include molecular beam/mass spectrometry and laser spectroscopy. Computional tools include multiphysics CFD, molecular dynamics and ab initio qunatum mechanics.

Current Research Projects

High Pressure Kinetics of Syngas and Nearly Pure Hydrogen Fuels (DOE University Turbine Systems Research Program) - The objective of this project is to develop the necessary chemical kinetics information to understand the combustion of syngas and nearly pure hydrogen fuels at conditions of interest in gas turbine combustion. Syngas is the product of the gasification of coal and/or biomass. The composition of syngas can vary considerably, but typically contains mostly hydrogen, CO and CO2 with smaller amounts of CH4, O2, N2, other hydrocarbons and water vapor. With further processing, the hydrogen content can be increased to fairly high levels. Both syngas and nearly pure H2 mixtures can be oxidized either with air, or with pure oxygen, or any combination thereof.   The use of any particular fuel/oxidizer combination in gas turbines will require an ability to predict important combustion properties such as laminar flame speed, autoignition conditions, flammability limits and NOx formation rates.

MEMS Colloid Thruster Array (TDA Research Inc. STTR Phase I and II programs funded by AFOSR) - Colloid thruster technology involves the emission of small droplets using the electrospray concept.  The recent advent of microelectromechanical systems (MEMS) technology and improved propellants has created renewed interest in the technology.  Colloid thruster arrays may produce large thrust levels, while maintaining the ability to deliver a small impulse bit from a single emitter, making them well suited to micro- and nano-satellites.  However, a number of technological barriers have prevented full development at the micro-scale.  In particular, simple fabrication strategies are needed to create dense two- dimensional thruster arrays.  Therefore, TDA Research, Inc., teamed with the University of Colorado at Boulder, has been designing and fabricating 2D colloid thruster arrays and studying their performance.

Actively Controlled Self-aspirating MEMS Fuel Injector (TDA Research Inc. SBIR funded by NSF) - The liquid fueled carburetor most commonly used in small gasoline fueled engines meters, injects and mixes the fuel with the air flowing to the engine.  However, the system cannot time the injection, so the engines suffer from relatively poor fuel economy and high emission levels.  Unfortunately, small engines account for significant amounts of HC, CO, NOx, and Particulate Matter emissions, which form smog and contain toxic compounds such as benzene, toluene, formaldehyde, acetaldehyde, and acrolein.  Due to this significant amount of pollution, the EPA has mandated emissions regulations for these engines, which existing technology will be unable to meet in a cost effective manner.  Therefore, TDA Research and the University of Colorado are developing low-cost MEMS fuel atomizers for timed injection.  This Phase I project will determine the feasibility of this new technology and establish a design.  In Phase II, we will build prototype MEMS atomizers, integrate them into a four-stroke engine and demonstrate their ability to reduce pollutants to below the planned regulated levels.

Biomass Thermochemical Processing (National Renwable Energy Laboratory) - Thermochemical processing of biomass materials is important for generation of biomass based fuels and other commercially valuable chemical products. When biomass is heated with no oxygen or only about one-third the oxygen needed for efficient combustion (amount of oxygen and other conditions determine if biomass gasifies or pyrolyzes), it gasifies to a mixture of carbon monoxide and hydrogen—synthesis gas or syngas. Other heating strategies can produce liquids, or be optimized for chemicals production. We are studying the chemical kinetics of biomass thermal decomposition to develop chemical mechanisms needed for process control. 

Modeling of Laser Excitation Dynamics for LIF Measurement of Small Radicals (In collaboration with Dr. Thomas Settersten of Sandia National Laboratory) - A study of the excitation dynamics of small molecules when excited by a laser for use of laser induced fluorescence (LIF) in combustion and CVD applications. The dynamics are modeled using the time dependent rate equations and compared with pump/probe measurements in low pressure flames and CVD reactors. Current work involves the use of trajectory calculations to obtain rotational energy transfer rates for NO with a variety of collision partners.

Optical Biopsy (In collaboration with faculty at the University of Colorado Health Sciences Center) - Prostate cancer remains the most common visceral cancer and second most common cause of cancer deaths in the United States. It is a disease characterized by a high prevalence and marked heterogeneity of its morphology as well as its clinical behavior.  The therapeutic management of patients with this disease requires precise information regarding: 1) the natural history of the disease, and 2) our ability to evaluate the status of the disease prior to radical therapy. Our approach is to utilize a biopsy needle mounted fiber optic array. The fiber array delivers the excitation light and collects scattered light. The simplest methodology involves directly measuring elastically scattered light. Elastic scattering has been used to classify a number of surface cancers, and seems promising. Indeed, preliminary absorption measurements carried out using tissues samples obtained from radical prostatectomy specimens showed clear spectral definition between normal and metastatic tissue. Testing of a more advanced method, laser induced fluorescence, is underway.