Solid Particle Dynamic Behavior Through Twisted Blade Rows

1984 ◽  
Vol 106 (3) ◽  
pp. 251-256 ◽  
Author(s):  
A. Hamed
Keyword(s):  
Particle Size ◽  
Flow Field ◽  
Particle Trajectory ◽  
Particle Dynamic ◽  
Mixed Flow ◽  
Essential Information ◽  
Trajectory Calculations ◽  
Machine Performance ◽  
Performance Deterioration ◽  
Twisted Blade

Particle trajectory calculations provide the essential information required for predicting the pattern and intensity of turbomachinery erosion. Consequently, accurate flow field and blade geometry representation in the trajectory computational model are required to evaluate machine performance deterioration due to erosion. A model is presented that is simple and efficient yet versatile and general, applicable to axial, radial and mixed flow machines, and to inlets, nozzles, return passages and separators. Computations are presented for particle trajectories through a row of twisted vanes in the inlet flow field. The effect of the particle size on trajectory blade impacts, and on particle redistribution and separation are discussed.

Particle trajectory calculations using finite element electromagnetic field maps

1988 ◽  
Vol 24 (6) ◽  
pp. 3126-3128 ◽  
Author(s):  
M.D.N. Lunney ◽  
R.B. Moore ◽  
J.P. Webb ◽  
B. Forghani
Keyword(s):  
Finite Element ◽  
Electromagnetic Field ◽  
Particle Trajectory ◽  
Trajectory Calculations

Influence of different blade numbers on the performance of “saddle zone” in a mixed flow pump

2021 ◽  
pp. 095765092110460
Author(s):  
Leilei Ji ◽  
Wei Li ◽  
Weidong Shi ◽  
Fei Tian ◽  
Shuo Li ◽  
...  
Keyword(s):  
Flow Field ◽  
Leading Edge ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Mixed Flow ◽  
Impeller Blade ◽  
Flow Angle ◽  
Tip Leakage ◽  
Vorticity Transport ◽  
Flow Pump

In order to study the effect of different numbers of impeller blades on the performance of mixed-flow pump “saddle zone”, the external characteristic test and numerical simulation of mixed-flow pumps with three different impeller blade numbers were carried out. Based on high-precision numerical prediction, the internal flow field and tip leakage flow field of mixed flow pump under design conditions and stall conditions are investigated. By studying the vorticity transport in the stall flow field, the specific location of the high loss area inside the mixed flow pump impeller with different numbers of blades is located. The research results show that the increase in the number of impeller blades improve the pump head and efficiency under design conditions. Compared to the 4-blade impeller, the head and efficiency of the 5-blade impeller are increased by 5.4% and 21.9% respectively. However, the increase in the number of blades also leads to the widening of the “saddle area” of the mixed-flow pump, which leads to the early occurrence of stall and increases the instability of the mixed-flow pump. As the mixed-flow pump enters the stall condition, the inlet of the mixed-flow pump has a spiral swirl structure near the end wall for different blade numbers, but the depth and range of the swirling flow are different due to the change in the number of blades. At the same time, the change in the number of blades also makes the flow angle at 75% span change significantly, but the flow angle at 95% span is not much different because the tip leakage flow recirculates at the leading edge. Through the analysis of the vorticity transport results in the impeller with different numbers of blades, it is found that the reasons for the increase in the values of the vorticity transport in the stall condition are mainly impacted by the swirl flow at the impeller inlet, the tip leakage flow at the leading edge and the increased unsteady flow structures.

Ultrafine particles in the cabin of a waiting commercial airliner at Tianjin International Airport, China

2017 ◽  
Vol 27 (9) ◽  
pp. 1247-1258 ◽  
Author(s):  
Jianlin Ren ◽  
Junjie Liu ◽  
Xiaodong Cao ◽  
Fei Li ◽  
Jianmin Li
Keyword(s):  
Particle Size ◽  
Ultrafine Particles ◽  
Size Range ◽  
Environmental Control ◽  
Particle Dynamic ◽  
Ground Vehicles ◽  
Flight Delays ◽  
Penetration Factor ◽  
International Airport ◽  
Outdoor Concentration

Passengers and crew on board of commercial airliners often spend extra time in the cabin waiting for departure due to flight delays. During the waiting period, a large amount of ambient ultrafine particles (UFPs) may penetrate into the aircraft cabin through the environmental control system (ECS) and ground air-conditioning cart (GAC). However, limited data are available for human exposure, in waiting commercial airliners, to freshly emitted UFPs from the exhaust of ground vehicles and airliners. To address this issue, we measured the ambient and in-cabin particle number concentrations and particle size distributions (PSDs) simultaneously in an MD-82 airliner parked at Tianjin International Airport, China. When air was supplied to the cabin by GAC, particle counts variation outdoors caused in-cabin variation with a 1–2 min delay. The in-cabin and ambient PSDs ranged from 15 to 600 nm were bimodal, with peaks at 30–40 and 70–90 nm. The GAC and ECS removed 1–73% particles in the size range of 15–100 nm and 30–47% in the size range of 100–600 nm. The relationship between the penetration factor and particle size was an inverted U-curve. An improved particle dynamic model from this study was used to calculate the time-dependent in-cabin UFPs concentrations with dramatic changes in outdoor concentration.

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

1986 ◽  
Author(s):  
W. Tabakoff ◽  
A. Hamed
Keyword(s):  
Flow Field ◽  
Gas Turbine ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Suspended Solid ◽  
Solid Particles ◽  
Two Stage ◽  
Particle Momentum ◽  
Performance Deterioration ◽  
And Performance

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.

TURBODYNA: Centrifugal/Centripetal Turbomachinery Dynamic Simulator and its Application on a Mixed Flow Turbine

2019 ◽  
Author(s):  
Bijie Yang ◽  
Ricardo Martinez-Botas
Keyword(s):  
Flow Field ◽  
Performance Prediction ◽  
Pressure Wave ◽  
Response Assessment ◽  
System Response ◽  
Mixed Flow ◽  
Dynamic Simulator ◽  
Unsteady Performance ◽  
1D Modelling ◽  
Rotor Mass

Abstract 1D modelling is crucial for turbomachinery unsteady performance prediction and system response assessment. The purpose of the paper is to describe a newly developed 1D modelling (TURBODYNA) for turbomachinery. Different from classic 1D modelling, in TURBODYNA, rotor has been meshed and its unsteadiness due to flow field time scale is considered. Instead of direct using of performances maps, source terms are added in Euler equation set to simulate the rotor. By comparing 1D modelling with 3D CFD results, It shows that rotor unsteadiness is indispensable for a better prediction. In addition, different variables response to pulse differently. In the rotor, mass flow is close to quasi-steady while entropy is significantly unsteady. TURBODYNA can capture these features correctly and provide an accurate prediction on pressure wave transportation.

scholarly journals Energetic ion injection and formation of the storm-time symmetric ring current

2006 ◽  
Vol 24 (12) ◽  
pp. 3547-3556 ◽  
Author(s):  
L. Xie ◽  
Z. Y. Pu ◽  
X. Z. Zhou ◽  
S. Y. Fu ◽  
Q.-G. Zong ◽  
...  
Keyword(s):  
Electric Field ◽  
Ring Current ◽  
Particle Trajectory ◽  
Three Dimensional ◽  
Extensive Study ◽  
Current Injection ◽  
Ion Injection ◽  
Convection Electric Field ◽  
Trajectory Calculations ◽  
Current Region

Abstract. An extensive study of ring current injection and intensification of the storm-time ring current is conducted with three-dimensional (3-D) test particle trajectory calculations (TPTCs). The TPTCs reveal more accurately the process of ring current injection, with the main results being the following: (1) an intense convection electric field can effectively energize and inject plasma sheet particles into the ring current region within 1–3 h. (2) Injected ions often follow chaotic trajectories in non-adiabatic regions, which may have implications in storm and ring current physics. (3) The shielding electric field, which arises as a consequence of enhanced convection and co-exists with the injection and convection electric field, may cause the original open trajectories of injected ions with higher energy to change into closed ones, thus playing a role in the formation of the symmetric ring current.

Development and Industrial Application of the “All-Over-Controlled Vortex Distribution Method” for Designing Radial and Mixed Flow Impellers

1992 ◽  
Author(s):  
S. J. Wang ◽  
M. J. Yuan ◽  
G. Xi ◽  
S. X. Liu ◽  
D. T. Qi ◽  
...  
Keyword(s):  
Flow Field ◽  
Centrifugal Compressor ◽  
Inverse Method ◽  
Three Dimensional ◽  
Industrial Applications ◽  
Mixed Flow ◽  
Distribution Method ◽  
Stream Surface ◽  
Surface Theory ◽  
Performance Curves

Sixteen years ago an inverse method of designing radial, mixed flow impellers was proposed by the first author of this paper, which was based on a quasi-three-dimensional stream surface theory. The contradictions between the full controlling of the flow field in the whole impeller and the designed bables’ smooth machinability can be perfectly resolved with the above method (So it is called “all-over-controlled vortex distribution method”). This paper presents the developments and industrial applications of the above method in the last decade. Two single centrifugal compressor model stages with the 3-D impellers designed by this method are studied in detail, and several performance curves of the multistage centrifugal compressors designed by this method are also presented.

Preparation of tailor-made supported catalysts using asymmetric flow field flow fractionation and their application in hydrogenation

2014 ◽  
Vol 3 (1) ◽  
pp. 87-98 ◽  
Author(s):  
Jens Baumgard ◽  
Marga-Martina Pohl ◽  
Udo Kragl ◽  
Norbert Steinfeldt
Keyword(s):  
Particle Size ◽  
Flow Field ◽  
Metallic Nanoparticles ◽  
Size Range ◽  
Separation Process ◽  
Proton Nuclear Magnetic Resonance ◽  
Field Flow Fractionation ◽  
Asymmetric Flow ◽  
Size And Shape ◽  
Flow Fractionation

AbstractThe optical, chemical, and catalytic properties of metallic nanoparticles (NPs) depend strongly on their particle size and shape. Therefore, the preparation of monodisperse metallic NPs is very important for fundamental studies and practical applications. However, the isolation of the different structures by separation from a polydisperse sample, especially in the size range below 10 nm, is not well applied so far. Here, the asymmetric flow field flow fractionation (AF4) is adapted for the preparative separation of the Pd NPs regarding their size and shape in the sub-10-nm size range. To prove the efficiency of the applied method, small-angle X-ray scattering (SAXS) and high-resolution transmission electron microscopy (TEM) were utilized to determine the particle size distribution at different stages of the separation process. A major benefit of this method compared to most of the other separation techniques, the removal of impurities during the separation process, was proven by proton nuclear magnetic resonance (NMR). The obtained results demonstrate that the AF4 is well suited for the rapid preparation of the purified uniform precious metal NPs at the applied size range. Single fractions of the different-sized and -shaped Pd NPs were deposited on titania (TiO2) and tested in the catalytic hydrogenation of 2,5 hydroxymethylfurfural (HMF) in aqueous solution under mild conditions. While the spherical-shaped particles show a high activity, the separated agglomerated particles show a higher selectivity to the desired products.

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