Gas Turbine Engine Particle Emission Characterization

ABSTRACT: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.