SBIR-STTR Award

Under this feasibility study, we will investigate innovative methods for characterizing particulate emissions with a high degree of specificity to nonvolatile soot. Currently, no single instrument is available that can provide complete characterization of soot emissions. Instrumentation for reliable detection and characterization of nonvolatile particulate matter to obtain mass concentration, particle number concentrations, size distributions and specific surface area are proposed. Integration of the methods will be used to provide the missing information needed for complete PM characterization. Calibration means for the set up and validation of these measurements will also be investigated. Laser induced incandescence (LII) techniques calibrated with NIST traceable means will be used to measure soot volume fraction, primary particle size, and specific PM surface area. Condensation particle counters (CPC) will be used to obtain particle concentrations. These measurements will be combined with the LII measurements to obtain soot equivalent mean volume diameter. Particle mobility detection methods will be used to obtain particle size distributions with corrections for soot aggregate morphology using the fractal dimensions and corrected drag for these aggregate particles. The LII measurements of primary particle size and equivalent mean volume diameter of soot will be used to qualify the mobility size distribution measurements.

Benefit:
The present SBIR Phase I program will lead to a measurement system for characterizing soot volume fraction, mass concentration, primary particle size, aggregate size distribution and mean size, and number concentration. This development may be scaled down to provide subsets of the information as needed. We expect to also provide calibration means to ensure the reliability of these measurements. Results made available with these integrated diagnostics will provide a complete characterization of nonvolatile PM emissions from gas turbine engines and other combustion sources such as diesel engines, direct injection gasoline engines, and power plants. PM characterization instruments that can reliably measure black carbon (soot) PM are needed by jet engine manufactures to support their development efforts required in meeting the more stringent emissions standards that are in place and expected in the future. These instruments will also be necessary to enforce compliance with these regulations. It is anticipated that subsets of the proposed integrated instruments will be required for PM measurements in urban areas including the areas in the vicinity of busy airports. Other commercial applications will include atmospheric studies of PM concentrations and how these nonvolatile particulate affect climate.

There is no single method available today that can reliably measure soot particle mass concentrations, number concentrations, PM specific surface area, and particle size distributions, especially with specificity to soot (black carbon, elemental carbon). It has been demonstrated that laser induced incandescence (LII) methods can reliably measure soot volume fraction, soot primary particle size, and volume specific surface area with very high specificity to elemental carbon. However, the method cannot measure aggregate size or size distributions. Under the Phase I program, we investigated an innovative method for measuring the soot aggregate size with a high degree of specificity to nonvolatile soot. The LII results when combined with the measurements from other existing methods (CPC and DMA) will provide more reliable PM mass concentration, number concentrations and directly measured soot particle size distributions. The ultimate goal of the Phase II program is to enhance the capabilities of the LII and to seamlessly integrate the LII with a CPC and a DMA instrument to provide comprehensive analysis of nonvolatile PM in real-time.

Benefit:
The availability of new mass measurement instruments, such as the LII, with ultra-low mass measurement sensitivity, will permit both engine developers and regulators to switch over from the current gravimetric method to the newly developed instruments for PM measurements in engine exhausts. By integrating the LII with other PM instruments, additional information can be extracted such as soot aggregate size. With regard to aircraft gas turbine engine emissions, the SAE E-31 Committee is specifically looking to qualify measurement techniques for the non-volatile components of particulate matter, namely soot or black carbon. Based on the extensive testing and comparisons performed by this committee, it appears to be leaning favorably towards the LII. This opens up another market opportunity for LII all gas turbine engine manufacturers will be interested in the LII to help them develop low particulate emission engines.The primary driver for the adoption of stringent particulate emissions and air quality standards around the world is to protect public health. The secondary driver is to protect public welfare which includes protecting our environment and the climate. The strict PM emission and air quality standards, in turn, are expected to be the key drivers in the future adoption of LII-based instruments. ---------- Hypersonic missile and glider development have become of paramount importance and has accelerated as a result of recent announcements regarding deployments by other countries. With flight speeds as high as Mach 10 to 27, atmospheric particulate including water droplets, snow, ice particles, graupel, etc. can impart severe damage to these vehicles with the potential of initiating failure in flight. Investigations of such impact characteristics and the development of protection systems involves extensive ground testing in hypersonic ranges. These tests require reliable in situ measurements of the various atmospheric particulate. Under this proposed program, advanced imaging systems are proposed that can characterize the atmospheric particulate for the development of a complete database of the size, shapes, and mass of particles that may be encountered by the hypersonic vehicles. These data on the atmospheric particulate will then be simulated in ground test facilities. High-speed imaging systems will be developed and made available to characterize these particulates to ensure that accurate simulations will be available. This effort will lead to the development of advanced three-dimensional imaging systems for the AEDC G-Range facility to provide data on simulated particulates. An airworthy high-speed imaging (HSI) flight probe will be developed for acquiring the in situ atmospheric particulate data needed for the simulations. A hardened imaging system for hydrometeor characterization will be developed to meet the requirements of the Holloman AFB HSTT to help the design of simulated rain conditions on the hypersonic test track. There is a compelling need to characterize the total emissions from aircraft engines including CO2, NOX, SOX, aerosol, and nonvolatile particulate matter (nvPM). Methods to characterize nvPM concentrations, size distributions, and number density that are fast and reliable are in high demand. Under this program, laser induced incandescence (LII) instruments will be refined and evaluated for measuring nvPM mass emissions and will provide additional information on the particulate specific surface area. This development will result in the refined LII instrument and the evolution of calibration means that will ensure reliable and accurate mass emissions characterizations. Integration of the LII instrument with the differential mobility analyzer (DMA), the condensation particle counter (CPC) and CO2 monitor will result in the availability of instrumentation to fully characterize nvPM emissions. These instruments will be refined in the laboratory and then will undergo thorough testing at AEDC/UTSI using the J 85 jet engine and operated on a wide range of fuels. Questions to be addressed include problems with calibration means and soot generation, possible dependencies on soot aggregate particle size and primary particle size, and consistency in the calibration means when the instrument is applied to a range of combustion systems.