Laser Measurements of Fly Ash Rebound Parameters for Use in Trajectory Calculations

Tabakoff, W.; Malak, M.

doi:10.1115/85-gt-161

Cited by 21 publications

(19 citation statements)

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“…Figure 10 (Ref. 36) shows typical LDV results for the velocity and directional restitution ratios. One can see that the restitution ratios exhibit variance around a mean value, which depends on the impact angle.…”

Section: Coating and Blade Materials Erosion Studies And Facilitiesmentioning

confidence: 99%

“…Flowfield representations in axial-flow machine trajectory simulations progressed from mean streamline combined with spanwise and cross-passage velocities from secondary-flow theory for turbines 42 to inviscid flow on a number of the blade-to-blade stream surfaces for multistage compressors. 43 This was combined with secondary flow and experimentally based streamwise and crossflow velocity gradients 36 near the end walls 44 for multistage turbines. On the other hand, early trajectory simulations in radial-flow machines 45,46 were based on flow solutions on the meridinal planes and panel methods.…”

Section: Numerical Simulations Of Particle Trajectories and Blade Eromentioning

confidence: 99%

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Erosion and Deposition in Turbomachinery

Hamed

Tabakoff

Wenglarz³

2006

Journal of Propulsion and Power

280

135

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This paper presents a review of erosion and deposition research in turbomachines and the associated degradation in engine performance caused by particulate matter ingestion. Parameters affecting surface material losses as a result of erosion and development of experimental and analytical approaches to predict flowpath erosion and deposition are discussed. Tests results that quantify the effects of temperature, impact particle composition, impact velocity and angle, and surface material composition are reviewed along with particle restitution data (ratios of rebound to impact velocities and angles). Development and application of models using these data to calculate surface erosion in turbomachinery are described. These models predict particle trajectories in turbomachinery passages to determine impact rates, impact velocities, impact angles and uses the experimentally-obtained erosion data to calculate material losses. Literature on the effects of erosion on turbomachine performance and life is surveyed. Mechanisms of particle delivery and attachment upon arrival at turbomachine flowpath surfaces are also discussed along with experiential models that have been developed to predict surface deposit buildup. Delivery to turbine surfaces can occur as a result of inertial flight, as for erosion, but also through transport mechanisms involving turbulence, Brownian diffusion, and thermophoresis. The particle size range, where each of these mechanisms is dominant for delivery to surfaces, is described. The history and experience of developing models that use these mechanisms to quantify particle delivery rates to turbine flow path surfaces is discussed, along with the use of sticking fraction data to determine the amount of material retained on the surfaces after delivery and the resulting deposit buildup rates. Finally, factors that control whether extreme rates of deposition can occur in turbomachinery are described. . His early experience involved dynamics and control for gyroscopic systems and manned space stations. Later experience concerned developing and applying analytical and experimental methods to evaluate deposition, erosion, and corrosion (DEC) in advanced energy systems (e.g., gas turbines and fuel cells) operating with alternate fuels. Currently, Dr. Wenglarz is Manager of Research at SCIES for a DOE-sponsored program supporting university gas turbine research nationwide. Dr. Wenglarz has over 80 publications and presentations including invited presentations at the Von Karman

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Section: Coating and Blade Materials Erosion Studies And Facilitiesmentioning

confidence: 99%

Section: Numerical Simulations Of Particle Trajectories and Blade Eromentioning

confidence: 99%

Erosion and Deposition in Turbomachinery

Hamed

Tabakoff

Wenglarz³

2006

Journal of Propulsion and Power

280

135

View full text Add to dashboard Cite

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“…It has been pointed out that the critical velocity for a particle to be captured in oblique impaction is lower than that negotiated for perpendicular impaction (Broom, 1979;Aylor and Ferrandino, 1985). Studies have shown that the rebound velocity for smaller impact angles is higher than that for larger angles and that the coefficient of restitution decreases with increases in incident angle of the impact (Tabakoff and Malak, 1987). Including consideration of oblique impaction in elastic and plastic impaction is therefore important.…”

Section: Knowledge Gap and Research Neededmentioning

confidence: 99%

An Overview of Airborne Nanoparticle Filtration and Thermal Rebound Theory

Givehchi

Tan

2014

Aerosol Air Qual. Res.

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This paper provides an overview of recent studies on the filtration of airborne nanoparticles. Classical filtration theory assumes that the efficiency of nanoparticle adhesion is at unity when nanoparticles strike a filter with a Brownian motion. However, it has been pointed out that small nanoparticles may have a sufficiently high impact velocity to rebound from the surface upon collision, a mechanism called thermal rebound. According to thermal rebound theory, the adhesion efficiency of nanoparticles decreases if their size is reduced. However, this phenomenon has not yet been clearly observed in experimental studies; there are still a number of uncertainties associated with the concept of thermal rebound, which is yet to be either proven or disproven. This review paper discusses the findings in the current literature related to thermal rebound theory.

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“…These correlations [13] are based on the experimental data obtained using LDV for particle laden flows over metal samples at various incidence angles and flow velocities in a special tunnel [6,7]. The ratios were found to be mainly dependent upon the impingement angle [15,16] for a given particlematerial combination.…”

Section: Trajectory Calculationsmentioning

confidence: 99%

The Dynamics of Suspended Solid Particles in a Two Stage Gas Turbine

Tabakoff

Hamed

1986

Volume 1: Turbomachinery

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Gas turbine engines operating in dusty environments are exposed to erosion and performance deterioration. In order to provide the basis for calculating the erosion and performance deterioration of turbines using pulverized coal, an investigation is undertaken to determine the three dimensional particle trajectories in a two stage turbine. The solution takes into account the influence of the variation in the three dimensional flow field. The change in particle momentum due to their collision with the turbine blades and casings is modeled using empirical equations derived from experimental Laser Doppler Velocimetry (LDV) measurements. The results show the three dimensional trajectory characteristics of the solid particles relative to the turbine blades. The results also show that the particle distribution in the flow field are determined by particle-blade impacts. The results obtained from this study indicate the turbine blade locations which are subjected to more blade impacts and hence more erosion damage.

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Laser Measurements of Fly Ash Rebound Parameters for Use in Trajectory Calculations

Cited by 21 publications

References 0 publications

Erosion and Deposition in Turbomachinery

Erosion and Deposition in Turbomachinery

An Overview of Airborne Nanoparticle Filtration and Thermal Rebound Theory

The Dynamics of Suspended Solid Particles in a Two Stage Gas Turbine

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