Various needle trap devices (NTDs) with different designs for different applications have been developed during the past decade. A theoretical model on the fundamentals of the NTD was recently proposed, which employed the theory of frontal (gas-solid) chromatography to describe the sampling process, where a gaseous sample was continuously introduced into the sorbent bed. In this investigation, different types of sorbent particles with different dimensions were packed into the needle as adsorbents. The effect of particle dimension, which would affect the packing density and consequently the capacity, the extraction efficiency, and desorption efficiency of the NTD were experimentally investigated and the proposed theory was validated. The results demonstrated that NTDs packed with small particles possess higher extraction capacity and efficiency but much higher resistance to flow as well. The higher resistance did not necessarily result in poor desorption efficiency, because desorption efficiency was affected by both the sorbent bed structure and the desorption gas flow. The relationships observed among those physical parameters provide valuable guidance on how to design an NTD with high performance potential for future applications. For particulate sampling, it was found that NTDs packed with different particles presented high collection efficiency of the particulates being investigated, and the collection efficiency was dominated by the pore size and distribution of the sorbent bed packed inside the needle. Collection efficiency also increased with increase in solidity of the sorbent bed; the increase in humidity of the aerosol sample; and the decrease of sampling rate. The results also provide valuable guidance on the optimisation of needle trap for particulate collection.

Various needle trap devices (NTDs) with different designs for different applications have been developed during the past decade. A theoretical model on the fundamentals of the NTD was recently proposed, which employed the theory of frontal (gas-solid) chromatography to describe the sampling process, where a gaseous sample was continuously introduced into the sorbent bed. In this investigation, different types of sorbent particles with different dimensions were packed into the needle as adsorbents. The effect of particle dimension, which would affect the packing density and consequently the capacity, the extraction efficiency, and desorption efficiency of the NTD were experimentally investigated and the proposed theory was validated. The results demonstrated that NTDs packed with small particles possess higher extraction capacity and efficiency but much higher resistance to flow as well. The higher resistance did not necessarily result in poor desorption efficiency, because desorption efficiency was affected by both the sorbent bed structure and the desorption gas flow. The relationships observed among those physical parameters provide valuable guidance on how to design an NTD with high performance potential for future applications. For particulate sampling, it was found that NTDs packed with different particles presented high collection efficiency of the particulates being investigated, and the collection efficiency was dominated by the pore size and distribution of the sorbent bed packed inside the needle. Collection efficiency also increased with increase in solidity of the sorbent bed; the increase in humidity of the aerosol sample; and the decrease of sampling rate. The results also provide valuable guidance on the optimisation of needle trap for particulate collection.

Particle ingestion is a prevalent issue for jet engines. During operation, sand and ash particles enter the engine and can cause serious problems, including erosion and buildup of Calcia-Magnesia-Alumina-Silicate (CMAS) deposits. Analyzing the particle mass concentration of the airflow can help better understand this issue. This can best be accomplished by sampling particles with a sampling probe at various locations within an engine. The present study is a continuation of a previous study that developed and evaluated a novel sampling probe. The present study seeks to modify the probe to optimize its sampling capability, to evaluate the aerodynamics of the modified probe through Particle Imaging Velocimetry (PIV), to gain insight on its ability to sample smaller particles, to characterize the movement of larger particles as they are sampled using Particle Tracking Velocimetry (PTV), and to develop a method to physically measure particle mass concentration. To accomplish this, a free jet rig was used to create a particle-laden flow, and the probe was placed at the jet exit to sample particles. A laser and camera system were used to capture images of the probe for PIV and PTV. A particle collection apparatus was designed to collect and weigh particles captured by the probe to measure mass concentration. The PIV results indicate that the probe exhibits sub-isokinetic sampling behavior. However, the PTV results show that large particles are not affected by non-isokinetic conditions. The mass concentration measured by the probe decreases when the flow Mach number increases due to the higher flow velocity causing particles to be spaced further apart. The mass concentration measured by the probe decreases when the probe yaw angle increases due to lower projected probe inlet area. / Master of Science / Sand and ash particles are harmful to jet engines. Particle ingestion can greatly affect the useful life of the engine. Particles erode the machinery within the engine, and they also melt to form mineral deposits, all of which degrades performance. One method that is being developed to better understand this problem is to sample particles at various locations in the engine using a sampling probe. The concept of a sampling probe is simple: particles are captured by the probe inside the engine, and the particles are collected outside the engine for analysis. This would give insight on particle behavior in the engine. The present study is a continuation of a previous study that developed and evaluated a novel sampling probe. The present study seeks to modify the probe to optimize its sampling capability, to use advanced imaging techniques to characterize the movement of air and particles entering the probe, and to safely collect and weigh particles captured by the probe. A compressed air jet was used to accelerate particles and create a particle-laden environment akin to the inside of an engine. The probe was placed at the exit of the jet to sample particles. A laser and camera system were used to capture images of the probe during the particle-sampling process. A particle collection apparatus was designed to safely collect and store particles captured by the probe for weighing. The image and weight data were then used to make conclusions about the probe's sampling capability.

Particle ingestion remains an important concern for turbine engines, specifically those in aircraft. Sand and related particles tend to become suspended in air, posing an omnipresent health threat to engine components. This issue is most prevalent during operation in sandy environments at low altitudes. Takeoffs and landings can blow a significant quantity of particulates into the air; these particulates may then be ingested by the engine. Helicopters and other Vertical Takeoff and Landing (VTOL) aircraft are at high risk of engine damage in these conditions. Compressor blades are especially vulnerable, as they may encounter the largest of particles. Robust and thorough experimental and computational studies have been conducted to understand the relationships between particle type, shape, and size and their effects on compressor and turbine blade wear. However, there is a lack of literature that focuses on sampling particles directly from the flow inside an engine. Instead, experimental studies that estimate the trajectories and behavior of particles are based upon the resulting erosion of blades and the expected aerodynamics and physics of the region. It is important to close this gap to fully understand the role of particulates in eroding engine components. This study investigated the performance of a particle-sampling probe designed to collect particles after the first compressor stage of a Rolls-Royce Allison Model 250 turboshaft engine. The engine was not used in this investigation; rather, a rig that creates a particle-laden jet was developed in order to determine probe sampling sensitivity with respect to varying angles of attack and flow Mach number. Particle image velocimetry (PIV) was utilized to understand the aerodynamic effects of the probe on smaller particles. / Master of Science / Aircraft jet engines are constantly exposed to particles suspended in the atmosphere. Most jet engines contain several stages of spinning blades. The first series of stages near the front of the engine comprise the compressor, while the series towards the end of the engine comprise the turbine. Engines depend on compressor blades to add energy to the flow via compression and turbine blades to extract energy from the flow after combustion. Thus, they are critical for the successful operation of the engine. The constant impact of airborne particulates against these blades causes erosion, which alters blade geometry and thereby engine performance. Depending on the turbine inlet temperature, particles may melt and clog the cooling passages in turbine blades, causing serious damage as the blades reach temperatures above their intended operating regime. These damages inhibit the ability of the engine to operate properly and pose a serious safety risk if left unchecked. In literature, experimental engine erosion correlations and numerical models of particle trajectories through the engine have been developed; however, none of these studies collected particles directly from the compressor region of the engine. In this study, a probe was developed and evaluated for the purpose of sampling particulates between the first and second compressor stages of a Rolls-Royce Allison Model 250 turboshaft engine. The probe's efficacy and aerodynamic properties were analyzed such that the probe will provide processable data when inserted into the engine. The methods to obtain this data include particle-sampling and particle image velocimetry (PIV).

Crankcase ventilation contributes significantly to diesel engine particulate emissions. Future regulations will not only limit the mass of particulate matter, but also the number of particles. Controlling the source of crankcase emissions is critical to meeting the perennial legislation. Deficiency in the understanding of crankcase emissions generation and the contribution of lubricating oil has been addressed in detail by the experimental study presented in this thesis. A plethora of high speed laser optical diagnostics techniques have been employed to deduce the main mechanisms of crankcase oil aerosol generation. Novel images have captured oil atomisation and passive oil distribution around the crankcase of an optically accessed, motored, four cylinder, off highway, heavy duty, diesel engine. Rayleigh type ligament breakup of oil films present on the surface of dynamic components, most notably the crankshaft, camshaft and valve rockers generated oil drops below 10 micrometers. Data illustrated not only crankcase oil aerosol generation at source, but it has provided valuable information on methods to control oil aerosol generation and improve oil circuit efficiency. The feasibility of utilising computational fluid dynamics to predict crankcase oil aerosol generation has been successfully assessed using the experimental data. Particle sampling has characterised the crankcase emissions from both a fired and motored diesel engine crankcase. The evolution of submicron crankcase particles down to 5 nm has been recorded from both engines, including the isolated contribution of engine oil, at a wide range of engine test points. Results have provided constructive insight into the generation and control of this complex emission. The main mechanism of crankcase oil aerosol generation was found to be crankshaft oil atomisation. This atomisation process has been analysed in detail, involving high speed imaging of primary and satellite drop generation and high speed digital particle image velocity of the crankshaft air flow. A promising mechanism of regulating and controlling crankcase oil aerosol emissions at source has been studied experimentally.