Assessment of Scavenge Efficiency for a Helicopter Particle Separation System

2012 ◽  
Vol 57 (2) ◽  
pp. 41-48 ◽  
Author(s):  
L.Y. Jiang ◽  
M. Benner ◽  
J. Bird
Keyword(s):  
Shape Factor ◽  
Particle Separation ◽  
Operating Conditions ◽  
Separation Mechanism ◽  
Separation System ◽  
Small Particles ◽  
Inlet Velocity ◽  
Separation Systems ◽  
Large Particles ◽  
Flow Field Characteristics

The effectiveness of a helicopter particle separation system has been numerically assessed at practical operating conditions and sand environments for various scenarios. The particle separation mechanism and its limitations are revealed by the predicted flow field characteristics and particle trajectories. The separation-by-inertia concept is effective for removing large particles, but problematic for small particles of diameter ≤36 μm for the configuration and operating conditions considered in the present study. It is also found that particle size, shape factor, and rebound characteristics exert substantial effects on particle scavenge efficiency. However, the effects of gravity, particle inlet velocity, inlet mass distribution, and engine-operating conditions on scavenge efficiency are minor or limited. Finally, a few suggestions for further investigation on engine particle separation systems are included.

Assessment of Scavenge Efficiency for a Helicopter Particle Separation System

2011 ◽  
Author(s):  
Leiyong Jiang ◽  
Michael Benner ◽  
Jeff Bird
Keyword(s):  
Shape Factor ◽  
Flow Characteristics ◽  
Particle Separation ◽  
Operating Conditions ◽  
Separation Mechanism ◽  
Separation System ◽  
Small Particles ◽  
Inlet Velocity ◽  
Separation Systems ◽  
Large Particles

The effectiveness of a typical helicopter particle separation system has been numerically assessed at practical operating conditions and sand environments for various scenarios. The particle separation mechanism and its limitation are revealed by the flow characteristics and particle trajectories in the flow-field. The separation-by-inertia concept is effective for removing large particles, but problematic for small particles of diameter (d) ≤ 36μm. The particle size, shape factor, and rebound characteristics exert substantial effects on particle scavenge efficiency. On the other hand, the effects of gravity, particle inlet velocity, inlet mass distribution, and engine operating conditions on scavenge efficiency are minor or limited for the configurations and operating conditions considered in the present study. In addition, a few suggestions for further investigation on engine particle separation systems are included.

Large Particle Separation From Non-Newtonian Slurries Using Bump Arrays

2021 ◽  
Author(s):  
Leonard F. Pease ◽  
Judith Ann Bamberger ◽  
Carolyn A. Burns ◽  
Michael J. Minette
Keyword(s):  
Nuclear Waste ◽  
Blood Cells ◽  
Large Particle ◽  
Lateral Displacement ◽  
Particle Separation ◽  
Small Particle Size ◽  
Small Particles ◽  
Deterministic Lateral Displacement ◽  
Significant Difference ◽  
Large Particles

Abstract Here we evaluate the performance of bump arrays to separate large particles from non-Newtonian slurries with Bingham and Cross rheology. Bump arrays in deterministic lateral displacement devices separate large particles from small particles using arrays of staggered posts. Large particles, defined as those with radii larger than the distance between the edge of a post and the stagnation streamline from the next downstream post, must bump toward one side of the device, whereas particles smaller than this distance slalom from entrance to exit without net lateral displacement. Although these devices have been used to separate a wide variety of large particles from blood cells to sand, partition of large particles from non-Newtonian fluids remains unexplored. Yet, an important set of modestly concentrated slurries, including Hanford nuclear waste, displays non-Newtonian rheology. Here we evaluate the influence of non-Newtonian rheology on the large-small particle size cutoff in bump arrays using a model that explores the influence of yield stresses, ratios of zero and infinite shear viscosities, and Cross’s exponent under strictly laminar well-developed conditions. Surprisingly, we find that viscosity ratios and Cross’s exponent make no significant difference on the particle cutoffs between large particles that bump and small particles that slalom around the posts from entrance to exit. In contrast, we find that yield stresses do significantly affect the size cutoff. As the yield stress increases, velocity profiles become more plug like lowering the size cutoff. For nuclear waste separations where removing large particles is a priority, increasing yield stresses is conservative.

Structure of Microphase-Separated Silica/Siloxane Molecular Composites

1989 ◽  
Vol 171 ◽  
Author(s):  
Dale W. Schaefer ◽  
James E. Mark ◽  
David Mccarthy ◽  
Li Jian ◽  
C. -C. Sun ◽  
...  
Keyword(s):  
Phase Separation ◽  
Kinetic Studies ◽  
Organic Content ◽  
Small Particles ◽  
X Ray ◽  
Filled Elastomers ◽  
Polymeric Networks ◽  
Large Particles ◽  
Molecular Composites

ABSTRACTThe structure of several classes of silica/siloxane molecular composites is investigated using small-angle x-ray and neutron scattering. These filled elastomers can be prepared through different synthethic protocols leading to a range of fillers including particulates with both rough and smooth surfaces, particulates with dispersed interfaces, and polymeric networks. We also find examples of bicontinuous filler phases that we attribute to phase separation via spinodal decomposition. In-situ kinetic studies of particulate fillers show that the precipitate does not develop by conventional nucleation-and-growth. We see no evidence of growth by ripening whereby large particles grow by consumption of small particles. Rather, there appears to be a limiting size set by the elastomer network itself. Phase separation develops by continuous nucleation of particles and subsequent growth to the limiting size. We also briefly report studies of polymer-toughened glasses. In this case, we find no obvious correlation between organic content and structure.

Characteristics of Flame Bases for V-Gutters Stabilized Premixed Flames

2013 ◽  
Author(s):  
Fan Gong ◽  
Yong Huang
Keyword(s):  
Thermal Conductivity ◽  
Temperature Gradient ◽  
Equivalence Ratio ◽  
Premixed Flames ◽  
Flame Stabilization ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Heat Conducting ◽  
Inlet Velocity ◽  
The Impact

The objective of this work is to investigate the flame stabilization mechanism and the impact of the operating conditions on the characteristics of the steady, lean premixed flames. It’s well known that the flame base is very important to the existence of a flame, such as the flame after a V-gutter, which is typically used in ramjet and turbojet or turbofan afterburners and laboratory experiments. We performed two-dimensional simulations of turbulent premixed flames anchored downstream of the heat-conducting V-gutters in a confined passage for kerosene-air combustion. The flame bases are symmetrically located in the shear layers of the recirculation zone immediately after the V-gutter’s trailing edge. The effects of equivalence ratio of inlet mixture, inlet temperature, V-gutter’s thermal conductivity and inlet velocity on the flame base movements are investigated. When the equivalence ratio is raised, the flame base moves upstream slightly and the temperature gradient dT/dx near the flame base increases, so the flame base is strengthened. When the inlet temperature is raised, the flame base moves upstream very slightly, and near the flame base dT/dx increases and dT/dy decreases, so the flame base is strengthened. As the V-gutter’s thermal conductivity increases, the flame base moves downstream, and the temperature gradient dT/dx near the flame base decreases, so the flame base is weakened. When the inlet velocity is raised, the flame base moves upstream, and the convection heat loss with inlet mixture increases, so the flame base is weakened.

Analysis of the Particles’ Movement Over the Flat and Profiled Rotating Discs surface in the Velocity Layer of the Viscous Gas

2021 ◽  
Vol 6 (2) ◽  
pp. 17-23
Author(s):  
Valeriy I. Pinakov ◽  
Konstantin V. Kulik ◽  
Boris E. Grinberg
Keyword(s):  
Qualitative Difference ◽  
Surface Region ◽  
Vertex Angle ◽  
Oscillation Regime ◽  
Small Particles ◽  
Magnus Force ◽  
Near Surface ◽  
Rotating Discs ◽  
Large Particles ◽  
Velocity Layer

Experiments on the rotating in the air cones with vertex angle β = 120º and flat disc shown that on frequencies Ω ≥ 2.5 hertz exists a qualitative difference in movement for the particles with diameters d ≈ 1 mm and d ≈ 0.1 mm. The particles with d ≈ 0.1 mm move in the near-surface region, the particles with d ≈ 1 mm jump up to 3 cm. Comparison of the spherical and aspheric (ellipsoid with axles d, d and 4 /3 d) particles' kinematics moving shown the inevitability of the large particles jump occurrence. Large particles come to self-oscillation regime by reason of periodically appearance of the Magnus force. Small particles are localized in the velocity layer

scholarly journals Gravitational differentiation in the regimes from stokes settling to Rayleigh–Raylor flows

2019 ◽  
pp. 15-30
Author(s):  
V. P. Trubitsyn
Keyword(s):  
Viscous Fluid ◽  
Interacting Particles ◽  
Small Particles ◽  
Continuous Transition ◽  
New Approach ◽  
Earth's Core ◽  
The Core ◽  
The Earth ◽  
Large Particles ◽  
Two Component

The Earth’s core was formed under gravitational differentiation in the course of the separation of iron and silicates. Most of the iron has gone into the core as early as when the Earth was growing. However, iron continued to precipitate even during the subsequent partial solidification which developed from the bottom upwards. At the different stages and in the different layers of the mantle, iron was deposited in different regimes. In this paper, the mechanisms of the deposition of a cloud of heavy interacting particles (or drops) in a viscous fluid are considered. A new approach suitable for analytical and numerical tracing the changes in the structure of the flows in a two-component suspension under continuous transition from the Stokessettling (for the case of a cloud of large particles) to the Rayleigh–Taylor flows and heavy diapirs (for the case of a cloud of small particles) is suggested. It is numerically and analytically shown that the both regimes are the different limiting cases of the sedimentation convection in suspensions.

scholarly journals Faulty Lock Detection and Separation System

2019 ◽  
pp. 39-44
Author(s):  
Mishra Nikhilkumar N ◽  
Madale Kabirdas N ◽  
Khairnar Pratik S ◽  
Sangale Prasad M ◽  
Ostwal Rishabh S
Keyword(s):  
Separation Mechanism ◽  
Conveyer Belt ◽  
Separation System ◽  
Locking Mechanism ◽  
Good Reputation ◽  
Product Manufacturing ◽  
Rubber Belt ◽  
Is Design ◽  
Belt System ◽  
Detection And Separation

All product manufacturing units need to have a faulty product detection and separation system in order to maintain product quality and maintain a good reputation. So here we demonstrate such a system using a mini conveyer belt system. We propose to design and fabricate a faulty product detection and separation mechanism. Each product is different and thus has different mechanisms to detect faulty products. Here we detect fault in lock based on its size and operations. We use a sensor to detect each lock size and operations as products move over a conveyer belt. The conveyer is design so that it can hold the lock so that it does not fall or leave the conveyer belt. A defected product with size lower than minimum limit will be automatically detected as it moves on a conveyer belt and separated by a conveyer arm. If the product passes the size test the next sensor perform it task to operate the lock so that it can open the locking mechanism and check if it opens or not. If the product passes the test it is send for packaging and if not the product is separated and sent to production line for correct the fault. Here we use rollers and rubber belt to develop a mini conveyer belt mechanism. This mechanism is operated by a motor. This system uses servo motor arm to separate the faulty product.

scholarly journals Flow and fouling in a pleated membrane filter

2016 ◽  
Vol 795 ◽  
pp. 36-59 ◽  
Author(s):  
P. Sanaei ◽  
G. W. Richardson ◽  
T. Witelski ◽  
L. J. Cummings
Keyword(s):  
Membrane Fouling ◽  
Membrane Filter ◽  
Small Particles ◽  
Porous Support ◽  
Equal Area ◽  
Membrane Filters ◽  
Membrane Pores ◽  
Dead End ◽  
Large Particles ◽  
Membrane Geometry

Pleated membrane filters are widely used in many applications, and offer significantly better surface area to volume ratios than equal-area unpleated membrane filters. However, their filtration characteristics are markedly inferior to those of equivalent unpleated membrane filters in dead-end filtration. While several hypotheses have been advanced for this, one possibility is that the flow field induced by the pleating leads to spatially non-uniform fouling of the filter, which in turn degrades performance. In this paper we investigate this hypothesis by developing a simplified model for the flow and fouling within a pleated membrane filter. Our model accounts for the pleated membrane geometry (which affects the flow), for porous support layers surrounding the membrane, and for two membrane fouling mechanisms: (i) adsorption of very small particles within membrane pores; and (ii) blocking of entire pores by large particles. We use asymptotic techniques based on the small pleat aspect ratio to solve the model, and we compare solutions to those for the closest-equivalent unpleated filter.

scholarly journals Scattering Properties of Cometary Dust Based on Polarimetric Data

1991 ◽  
Vol 126 ◽  
pp. 249-252
Author(s):  
Sonoyo Mukai ◽  
Tadashi Mukai ◽  
Sen Kikuchi
Keyword(s):  
Linear Polarization ◽  
Phase Function ◽  
Mie Scattering ◽  
Mixing Ratio ◽  
Small Particles ◽  
Cometary Dust ◽  
Maximum Polarization ◽  
Large Particles ◽  
Lower Maximum ◽  
Phase Angles

AbstractReferring to the dust model in Mukai and Mukai(1990), where the scattering by large rough particles and Mie scattering by small particles are taken into account, a phase function of linear polarization of several comets is examined, especially in a region of phase angles α near a maximum polarization. A lower maximum polarization observed in comet Austin(1989c1) than those in comets West(1975n) and P/Halley leads a speculation that a mixing ratio of rough scattering to Mie scattering in comet Austin increases from a sun-comet distance r of 0.6 AU to 1.2 AU. This implies that a shortage of large particles in comet Austin occured in r <1 AU.

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