A Numerical Model for Simulating Liquid Particles Deposition on Surface

2018 ◽  
Author(s):  
Zhenxia Liu ◽  
Fei Zhang ◽  
Zhengang Liu
Keyword(s):  
Particle Size ◽  
Numerical Model ◽  
Particle Deposition ◽  
Surface Profile ◽  
Leading Edge ◽  
Solid Particles ◽  
Liquid Particle ◽  
Aircraft Icing ◽  
Turbine Vane ◽  
Deposition Thickness

The deposition of liquid particles, which may be converted from solid particles due to high temperature gas heating, makes much more harm on turbine vane blades compared to solid particles, since it may block film-cooling holes, worsen the cooling efficiency and aerodynamic performance of the turbine vane blades. Due to the similarity between the deposition of liquid particles on a surface and the icing on a surface, a numerical model for simulating particles deposition was developed based on the Myers icing model, an extension of the Messinger model, which has been applied in predicting aircraft icing or aero-engine icing. Compared to the conventional liquid particle deposition model, the numerical model in this paper considers the heat transfer and the flow of liquid particles during the particles phase transition from liquid state to solid state. In this model, the change of the surface profile due to the particles deposition was also considered, which was implemented with dynamic mesh technique. To test this model, deposition distribution and thickness obtained from the numerical simulations were compared to the experimental results. Additionally, a numerical simulation was conducted for liquid particle deposition on a flat plate. The result showed that the deposition thickness at the leading edge was much larger than that on the upper surface where the deposition appeared mainly at the middle and rear of the plate. The deposition mass and thickness increased with the increasing in the particle size. The effect of the particle size on the deposition thickness was more notable on the upper surface compared to that at the leading edge.

Effect of Stress Wave Scattering at the Liquid-Particle Interface on Viscosity Calculation of Nanocolloidal Dispersions

2008 ◽  
Author(s):  
Tao Wang ◽  
Xinwei Wang ◽  
Haiping Hong ◽  
Zhongyang Luo ◽  
Kefa Cen
Keyword(s):  
Particle Size ◽  
Autocorrelation Function ◽  
Stress Wave ◽  
Wave Scattering ◽  
Volume Fraction ◽  
Solid Particles ◽  
Spherical Particles ◽  
Computational Domain ◽  
Liquid Particle ◽  
Pressure Tensor

In this work, extensive equilibrium molecular dynamics simulations are conducted to study the shear viscosity of nanocolloidal dispersion. Strong oscillation of the pressure tensor autocorrelation function is observed. The computational domain contains solvent of liquid argon at 143.4 K and spherical particles with volume fraction of 3%. By studying the effect of the particle size, particle density, and acoustic impedance, it is found for the first time that the stress wave scattering/reflecting at the liquid-particle interface due to acoustic mismatch plays a critical important role in the oscillation of pressure tensor autocorrelation function. The Brownian motion/vibration of solid particles is considered to have little effect on the oscillation of pressure tensor autocorrelation function curve except the frequency. And when the particle size is comparable with the wavelength of stress wave, the diffraction of stress wave happens at the interface that will also weaken the oscillation of pressure tensor autocorrelation function.

Comparison Between the Numerical and Experimental Deposition Patterns for an Electrostatic Rotary Bell Sprayer

2015 ◽  
Author(s):  
Husam Osman ◽  
Kazimierz Adamiak ◽  
G. S. Peter Castle ◽  
Hua-Tzu (Charles) Fan ◽  
Joseph Simmer
Keyword(s):  
Numerical Model ◽  
Mass Flow Rate ◽  
Flow Rate ◽  
Particle Deposition ◽  
Numerical Results ◽  
Deposition Patterns ◽  
Dispersed Particles ◽  
3D Numerical Model ◽  
Deposition Thickness ◽  
Fractional Mass

In this paper, a full 3D numerical model using ANSYS commercial software has been created to simulate the particle deposition profile for stationary and moving flat targets, assuming multiple injections of charged poly-dispersed particles. Different injection angles along three virtual rings were assumed to form a shower injection pattern. The experimental and the numerical results of deposition thickness have been presented and compared for different injection patterns. It has been found that there are some parameters, such as the total number of injection points, the radii of the rings and the fractional mass flow rate in each injection ring, which affect the numerical results of the deposition thickness and uniformity.

Effect of Blowing Ratio on Syngas Flyash Particle Deposition on a Three-Row Leading Edge Film Cooling Geometry Using Large Eddy Simulations

2009 ◽  
Author(s):  
Sai Shrinivas Sreedharan ◽  
Danesh K. Tafti
Keyword(s):  
Film Cooling ◽  
Particle Deposition ◽  
Numerical Study ◽  
Leading Edge ◽  
Stagnation Region ◽  
Blowing Ratio ◽  
Eddy Simulation ◽  
Lagrangian Framework ◽  
Large Eddy ◽  
Turbine Vane

A numerical study is performed to investigate deposition and erosion of Syngas ash in the leading edge region of a turbine vane. The leading edge of the vane is modeled as a symmetric semi-cylinder with a flat after body. Three rows of coolant holes located at stagnation and at ±21.3° from stagnation are simulated at blowing ratios of 0.5, 1.0, 1.5 and 2.0. Large Eddy Simulation (LES) is used to model the flow field of the coolant jet-mainstream interaction and syngas ash particles are modeled using a Lagrangian framework. Ash particle sizes of 5 and 7 micron are considered. Under the conditions of the current simulations, both ash particles have Stokes numbers less than unity of O(1) and hence are strongly affected by the flow and thermal field generated by the coolant interaction with the mainstream. Because of this, the stagnation coolant jets are quite successful in pushing the particles away from the surface and minimizing deposition and erosion in the stagnation region. Overall, about 10% of the 5 μm particles versus 20% of the 7 μm particles are deposited on the surface at B.R. = 0.5. An increase to B.R. = 2, increases deposition of the 5 micron particles to 14% while decreasing deposition of the 7 micron particles to 15%. Erosive ash particles of 5 μm size increase from 5% of the total to 10% as the blowing ratio increases from 0.5 to 2.0, whereas 7 μm erosive particles remain nearly constant at 15%. Overall, for particles of size 5 μm, there is a combined increase in deposition and erosive particles from 16% to 24% as the blowing ratio increases from 0.5 to 2.0. The 7 μm particles, on the other hand decrease from 35% to about 30% as the blowing ratio increases from 0.5 to 2.

scholarly journals A Numerical Study of the Effect of Particle Size on Particle Deposition on Turbine Vanes and Blades

2021 ◽  
Vol 13 (5) ◽  
pp. 168781402110178
Author(s):  
Zhengang Liu ◽  
Weinan Diao ◽  
Zhenxia Liu ◽  
Fei Zhang
Keyword(s):  
Particle Size ◽  
Particle Deposition ◽  
Numerical Study ◽  
Stokes Number ◽  
Capture Efficiency ◽  
Particle Capture ◽  
Factors Affecting ◽  
Pressure Surface ◽  
Deposition Area ◽  
Turbine Vanes

Particle deposition could decrease the aerodynamic performance and cooling efficiency of turbine vanes and blades. The particle motion in the flow and its temperature are two important factors affecting its deposition. The size of the particle influences both its motion and temperature. In this study, the motion of particles with the sizes from 1 to 20 μm in the first stage of a turbine are firstly numerically simulated with the steady method, then the particle deposition on the vanes and blades are numerically simulated with the unsteady method based on the critical viscosity model. It is discovered that the particle deposition on vanes mainly formed near the leading and trailing edge on the pressure surface, and the deposition area expands slowly to the whole pressure surface with the particle size increasing. For the particle deposition on blades, the deposition area moves from the entire pressure surface toward the tip with the particle size increasing due to the effect of rotation. For vanes, the particle capture efficiency increases with the particle size increasing since Stokes number and temperature of the particle both increase with its size. For blades, the particle capture efficiency increases firstly and then decreases with the particle size increasing.

Unsteady simulations of migration and deposition of fly-ash particles in the first-stage turbine of an aero-engine

2021 ◽  
pp. 1-21
Author(s):  
Z. Hao ◽  
X. Yang ◽  
Z. Feng
Keyword(s):  
Fly Ash ◽  
Film Cooling ◽  
Particle Deposition ◽  
Flow Characteristics ◽  
Leading Edge ◽  
Velocity Model ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Internal Cooling ◽  
Aero Engine

Abstract Particulate deposits in aero-engine turbines change the profile of blades, increase the blade surface roughness and block internal cooling channels and film cooling holes, which generally leads to the degradation of aerodynamic and cooling performance. To reveal particle deposition effects in the turbine, unsteady simulations were performed by investigating the migration patterns and deposition characteristics of the particle contaminant in a one-stage, high-pressure turbine of an aero-engine. Two typical operating conditions of the aero-engine, i.e. high-temperature take-off and economic cruise, were discussed, and the effects of particle size on the migration and deposition of fly-ash particles were demonstrated. A critical velocity model was applied to predict particle deposition. Comparisons between the stator and rotor were made by presenting the concentration and trajectory of the particles and the resulting deposition patterns on the aerofoil surfaces. Results show that the migration and deposition of the particles in the stator passage is dominated by the flow characteristics of fluid and the property of particles. In the subsequential rotor passage, in addition to these factors, particles are also affected by the stator–rotor interaction and the interference between rotors. With higher inlet temperature and larger diameter of the particle, the quantity of deposits increases and the deposition is distributed mainly on the Pressure Side (PS) and the Leading Edge (LE) of the aerofoil.

Investigation of the different particle size dust releases from rigid filter candles during pulse-jet cleaning

2021 ◽  
pp. 095440622110179
Author(s):  
Xin Luan ◽  
Zhongli Ji ◽  
Longfei Liu ◽  
Ruifeng Wang
Keyword(s):  
Particle Size ◽  
Critical Role ◽  
Operating Conditions ◽  
Solid Particles ◽  
Dust Particles ◽  
Cleaning Efficiency ◽  
Term Operation ◽  
Cleaning Performance ◽  
Experimental Apparatus ◽  
Pulse Jet

Rigid filters made of ceramic or metal are widely used to remove solid particles from hot gases at temperature above 260 °C in the petrochemical and coal industries. Pulse-jet cleaning of fine dust from rigid filter candles plays a critical role in the long-term operation of these filters. In this study, an experimental apparatus was fabricated to investigate the behavior of a 2050 mm filter candle, which included monitoring the variation of pressure dynamic characteristics over time and observing the release of dust layers that allowed an analysis of the cleaning performance of ISO 12103-1 test dusts with different particle size distributions. These results showed the release behavior of these dusts could be divided into five stages: radial expansion, axial crack, flaky release, irregular disruption and secondary deposition. The cleaning performance of smaller sized dust particles was less efficient as compared with larger sized dust particles under the same operating conditions primarily because large, flaky-shaped dust aggregates formed during the first three stages were easily broken into smaller, dispersed fragments during irregular disruption that forced more particles back to the filter surface during secondary deposition. Also, a “low-pressure and long-pulse width” cleaning method improved the cleaning efficiency of the A1 ultrafine test dust from 81.4% to 95.9%.

Penetration Dynamics of Solid Particles into Liquids High-Speed Experimental Results and Modelling

2005 ◽  
Vol 473-474 ◽  
pp. 429-434 ◽  
Author(s):  
Olga Verezub ◽  
György Kaptay ◽  
Tomiharu Matsushita ◽  
Kusuhiro Mukai
Keyword(s):  
Contact Angle ◽  
Particle Size ◽  
Aqueous Solutions ◽  
Particle Velocity ◽  
Weber Number ◽  
High Speed ◽  
Solid Particles ◽  
Bulk Liquid ◽  
Distilled Water ◽  
Critical Weber Number

Penetration of model solid particles (polymer, teflon, nylon, alumina) into transparent model liquids (distilled water and aqueous solutions of KI) were recorded by a high speed (500 frames per second) camera, while the particles were dropped from different heights vertically on the still surface of the liquids. In all cases a cavity has been found to form behind the solid particle, penetrating into the liquid. For each particle/liquid combination the critical dropping height has been measured, above which the particle was able to penetrate into the bulk liquid. Based on this, the critical impact particle velocity, and also the critical Weber number of penetration have been established. The critical Weber number of penetration was modelled as a function of the contact angle, particle size and the ratio of the density of solid particles to the density of the liquid.

Improvement in Precision, Accuracy, and Efficiency in Standardizing the Characterization of Granular Materials

2013 ◽  
Author(s):  
J. R. Tucker ◽  
L. J. Shadle ◽  
S. Benyahia ◽  
J. Mei ◽  
C. Guenther ◽  
...  
Keyword(s):  
Particle Size ◽  
Distribution Density ◽  
Particle Density ◽  
Solid Particles ◽  
Minimum Fluidization Velocity ◽  
Void Fractions ◽  
Multiphase Systems ◽  
Precision And Accuracy ◽  
Accuracy And Repeatability

Useful prediction of the kinematics, dynamics, and chemistry of a system relies on precision and accuracy in the quantification of component properties, operating mechanisms, and collected data. In an attempt to emphasize, rather than gloss over, the benefit of proper characterization to fundamental investigations of multiphase systems incorporating solid particles, a set of procedures were developed and implemented for the purpose of providing a revised methodology having the desirable attributes of reduced uncertainty, expanded relevance and detail, and higher throughput. Better, faster, cheaper characterization of multiphase systems result. Methodologies are presented to characterize particle size, shape, size distribution, density (particle, skeletal and bulk), minimum fluidization velocity, void fraction, particle porosity, and assignment within the Geldart Classification. A novel form of the Ergun equation was used to determine the bulk void fractions and particle density. Accuracy of properties-characterization methodology was validated on materials of known properties prior to testing materials of unknown properties. Several of the standard present-day techniques were scrutinized and improved upon where appropriate. Validity, accuracy, and repeatability were assessed for the procedures presented and deemed higher than present-day techniques. A database of over seventy materials has been developed to assist in model validation efforts and future designs.

scholarly journals Two-Phase Dusty Fluid Flow Along a Rotating Axisymmetric Round-Nosed Body

2017 ◽  
Vol 139 (8) ◽  
Author(s):  
Sadia Siddiqa ◽  
Naheed Begum ◽  
M. A. Hossain ◽  
Rama Subba Reddy Gorla
Keyword(s):  
Boundary Layer ◽  
Flow Characteristics ◽  
Leading Edge ◽  
Solid Particles ◽  
Dust Particles ◽  
Computational Domain ◽  
Two Phase ◽  
Carrier Fluid ◽  
Boundary Layer Equations ◽  
Implicit Finite Difference

This article is concerned with the class of solutions of gas boundary layer containing uniform, spherical solid particles over the surface of rotating axisymmetric round-nosed body. By using the method of transformed coordinates, the boundary layer equations for two-phase flow are mapped into a regular and stationary computational domain and then solved numerically by using implicit finite difference method. In this study, a rotating hemisphere is used as a particular example to elucidate the heat transfer mechanism near the surface of round-nosed bodies. We will investigate whether the presence of dust particles in carrier fluid disturbs the flow characteristics associated with rotating hemisphere or not. A comprehensive parametric analysis is presented to show the influence of the particle loading, the buoyancy ratio parameter, and the surface of rotating hemisphere on the numerical findings. In the absence of dust particles, the results are graphically compared with existing data in the open literature, and an excellent agreement has been found. It is noted that the concentration of dust particles’ parameter, Dρ, strongly influences the heat transport rate near the leading edge.

Impact Test for the Leading Edge of CMC Vane Based on Actual Aircraft Engine Field Data

2018 ◽  
Author(s):  
Kenro Obuchi ◽  
Fumiaki Watanabe ◽  
Hiroshi Kuroki ◽  
Hiroyuki Yagi ◽  
Kazuyoshi Arai
Keyword(s):  
Impact Test ◽  
Impact Resistance ◽  
Leading Edge ◽  
Aircraft Engine ◽  
Aircraft Engines ◽  
Turbine Vanes ◽  
Turbine Vane ◽  
Nickel Based Alloy ◽  
Weight Impact ◽  
The Impact

Ceramic matrix composites (CMCs) have lower density and a higher service temperature limit than nickel based alloys which have been used for turbine components of aircraft engines. These properties of CMCs have the potential to reduce the weight of turbine components and improve turbine thermal efficiency with a higher turbine inlet temperature (TIT). One of the technical issues of the CMC turbine vane is a relatively lower impact resistance than nickel based alloy turbine vanes. There are various previous works about impact resistance of CMCs, but there is little work that assumed actual engine conditions. The objective of this work was to verify the resistance of SiC/SiC CMC turbine vane to the impact phenomena that occur in the actual aircraft engine. The field damage survey was conducted on actual metal turbine vanes of commercial engines overhauled in IHI. The survey made it clear that the typical damage was less-than-0.127-mm-dent at the leading edge. In addition, the dropped weight impact test using the actual turbine airfoil which is made from a nickel based alloy was conducted at ambient temperature. The amount of energy required to make the dent of a certain size that was observed in actual metal turbine vanes was estimated. Then, the dropped weight impact test using the CMC test piece with a leading edge shape was conducted at the impact energy estimated by the metal turbine airfoil. The results showed that the failure mode of the CMC test piece was local damage with dents of a certain size and not a catastrophic failure mode. From this work, the damage to be assumed on CMC vane in actual aircraft engines was identified. As a future task, the effect of the damage to the fatigue capability of CMC turbine vanes needs to be investigated.

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