scholarly journals Coarse Particle Motion Characteristics in a Double-Stage Slurry Pump Considering Leakage Flow

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Hao Jia ◽  
Yuqi Wang ◽  
Zuchao Zhu ◽  
Xianghui Su ◽  
Zhenji Tang
Keyword(s):  
Kinetic Energy ◽  
Particle Motion ◽  
Mining Industry ◽  
Main Flow ◽  
Average Kinetic Energy ◽  
Leakage Flow ◽  
Coarse Particles ◽  
Long Distance ◽  
Pump Design ◽  
Motion Characteristics

Along with the pressing demand for the long-distance transportation of coarse particles in the deep-sea mining industry, evaluating the slurry pump’s passing through and erosive wear by studying the particle motion characteristics and the slurry behavior is becoming increasingly important. Research on the influence of leakage flow through the clearance and balancing devices on the motion characteristic of granular grain flow is of great significance but has been seldom studied. This study coupled the discrete element method with the CFD method to investigate the comprehensive effect of a double-stage slurry pump’s main flow and leakage flow on the motion characteristics of particles with a 10 mm diameter. Results show that the leakage flow occupation in main flow falls from 26%–27% to 8%–9% for the two stages, with the flow rate increasing from 80 m3/h to 200 m3/h. In the first stage with leakage, accumulation of coarse particles was observed at the impeller eye, which should be paid much attention to slurry pumps’ operation to eliminate the chance of blockage. In the nonleak situation, although the increment of the average kinetic energy of particles through the impeller is more significant than in the leak case, most of them dissipate primarily by more than 10% collision in the bowl diffuser. In the leak or nonleak case, the average kinetic energy of particles was more than twice through the first stage but only 1.1 times through the second stage. The selection of stages in the slurry pump design should consider the limitation of particle velocity improvement.

scholarly journals Influence of Seal Cavity Leakage Flow on Compressor Performance Investigated with a Circumferentially Averaged Method

2021 ◽  
Vol 11 (2) ◽  
pp. 780
Author(s):  
Dong Liang ◽  
Xingmin Gui ◽  
Donghai Jin
Keyword(s):  
Flow Field ◽  
Pressure Ratio ◽  
Interaction Mechanism ◽  
Main Flow ◽  
Leakage Flow ◽  
Destructive Effect ◽  
Through Flow ◽  
Compressor Performance ◽  
Overall Performance ◽  
Flow Blockage

In order to investigate the effect of seal cavity leakage flow on a compressor’s performance and the interaction mechanism between the leakage flow and the main flow, a one-stage compressor with a cavity under the shrouded stator was numerically simulated using an inhouse circumferentially averaged through flow program. The leakage flow from the shrouded stator cavity was calculated simultaneously with main flow in an integrated manner. The results indicate that the seal cavity leakage flow has a significant impact on the overall performance of the compressor. For a leakage of 0.2% of incoming flow, the decrease in the total pressure ratio was 2% and the reduction of efficiency was 1.9 points. Spanwise distribution of the flow field variables of the shrouded stator shows that the leakage flow leads to an increased flow blockage near the hub, resulting in drop of stator performance, as well as a certain destructive effect on the flow field of the main passage.

Interaction of Shroud Leakage Flow and Main Flow in a Three-Stage LP Turbine

2003 ◽  
Vol 127 (4) ◽  
pp. 649-658 ◽  
Author(s):  
Jochen Gier ◽  
Bertram Stubert ◽  
Bernard Brouillet ◽  
Laurent de Vito
Keyword(s):  
Main Flow ◽  
Secondary Flows ◽  
Test Facility ◽  
Navier Stokes ◽  
Leakage Flow ◽  
Jet Engines ◽  
Flow Interactions ◽  
Lp Turbine ◽  
The Impact ◽  
The Ideal

Endwall losses significantly contribute to the overall losses in modern turbomachinery, especially when aerodynamic airfoil load and pressure ratios are increased. In turbines with shrouded airfoils a large portion of these losses are generated by the leakage flow across the shroud clearance. Generally the related losses can be grouped into losses of the leakage flow itself and losses caused by the interaction with the main flow in subsequent airfoil rows. In order to reduce the impact of the leakage flow and shroud design related losses a thorough understanding of the leakage losses and especially of the losses connected to enhancing secondary flows and other main flow interactions has to be understood. Therefore, a three stage LP turbine typical for jet engines is being investigated. For the three-stage test turbine 3D Navier-Stokes computations are performed simulating the turbine including the entire shroud cavity geometry in comparison with computations in the ideal flow path. Numerical results compare favorably against measurements carried out at the high altitude test facility at Stuttgart University. The differences of the simulations with and without shroud cavities are analyzed for several points of operation and a very detailed quantitative loss breakdown is presented.

scholarly journals INVESTIGATION OF THE 16O(γ, p)3H3α REACTION AT THE ENERGIES BELOW THE MESON PRODUCTION THRESHOLD

2021 ◽  
pp. 68-71
Author(s):  
S.N. Afanasiev
Keyword(s):  
Kinetic Energy ◽  
Cross Section ◽  
Meson Production ◽  
Diffusion Chamber ◽  
Relative Energy ◽  
Photon Absorption ◽  
Average Kinetic Energy ◽  
Bremsstrahlung Photons ◽  
Mechanism Of Interaction ◽  
The Cross

The reaction 16O(γ, p)3H3 induced by bremsstrahlung photons of endpoint energy Emaxγ = 150 MeV has been studied by the method of a diffusion chamber in a magnetic field. The energy dependence of the total cross section has been measured in the energy range from the threshold and has been founded a broad resonance centered at 55 MeV. The rate of decrease in the cross section undergoes a change in the region around 55 MeV. A comparison was made with the cross section for reactions 4He(γ, p)3H and 12С(γ, р)3H2. The agreement between the shapes of distributions for the (γ, p)3H reactions is evident and was concluded that the mechanism of interaction of the γ-quantum with the nucleus is similar. The dependence of average kinetic energy of particles on the total kinetic energy was determined. In the whole energy interval, the distribution for a proton is more than the statistical distribution. Distribution of relative energy of the proton and 3H nucleus in their c.m.s. does not agree with the predictions of the mechanism of photon absorption by an α-particle cluster, but at energies above the maximum, it agrees with calculations within the framework of the quasi-deuteron model of photoabsorption.

A Theoretical Investigation of the Kinetic Energy of Ions Trapped in a Radio-Frequency Hexapole Ion Trap

2002 ◽  
Vol 8 (2) ◽  
pp. 181-189 ◽  
Author(s):  
Liam A. McDonnell ◽  
Anastassios E. Giannakopulos ◽  
Peter J. Derrick ◽  
Youri O. Tsybin ◽  
Per Håkansson
Keyword(s):  
Kinetic Energy ◽  
Radio Frequency ◽  
Space Charge ◽  
Free Path ◽  
Ion Trap ◽  
Mean Free Path ◽  
Ion Source ◽  
Average Kinetic Energy ◽  
Negative Consequences ◽  
Covalent Adducts

The kinetic energy dependence of ions trapped in a radio-frequency (RF) hexapole ion trap has been calculated as a function of space charge, mean free path, mass, RF potential and charge. The average kinetic energy of the ions was found to increase with increasing space charge, mean free path and the ion charge state. For a trapped ion in a given coulombic field, the mass of the ion and the amplitude of the applied RF potential did not affect the average kinetic energy. The consequences for multipole-storage-assisted dissociation (MSAD), in which ions are accumulated for prolonged periods of time in the multipole ion trap of an electrospray ion source, are discussed. As a result of radial stratification inside the ion trap, MSAD can lead to the preferential excitation of ions with larger m/z values. Such discrimination would have negative consequences for the detection of labile non-covalent adducts, which are normally detected at higher m/z values than their constituent species.

Influence of Labyrinth Seal Leakage on Centrifugal Compressor Performance

2009 ◽  
Author(s):  
Bob Mischo ◽  
Beat Ribi ◽  
Christof Seebass-Linggi ◽  
Sebastiano Mauri
Keyword(s):  
Centrifugal Compressor ◽  
Leading Edge ◽  
Suction Side ◽  
Labyrinth Seal ◽  
Main Flow ◽  
Low Flow ◽  
Leakage Flow ◽  
Multi Stage ◽  
Compressor Impeller ◽  
Rotating Impeller

The focus of this paper lies on the leakage flow across the shroud of a centrifugal compressor impeller. It is common practice to use shrouded impellers in multi stage compressors featuring a single shaft. The rotating impeller then has to be sealed against the higher pressure in the downstream diffuser by means of labyrinths. The relative amount of leakage is higher for stages designed for low flow, meaning that the associated losses gain in relevance. In addition to this loss source, the injection of the leakage flow has a serious influence on the main flow in a region where it is prone to separation, i.e. at the suction side of the impeller blades close to the shroud, where the highest relative velocities are found. The present paper discusses the numerical results of several geometrical arrangements where the leakage flow was mixed with the main flow in different ways. The distance between the location of injection and the leading edge of the impeller as well as the orientation of the injected flow showed a distinct influence on the performance of the entire stage, mainly on stability.

scholarly journals Influence of DC Electric Fields on Pollution of HVDC Composite Insulator Short Samples with Different Environmental Parameters

Energies ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 2304 ◽  
Author(s):  
Xinhan Qiao ◽  
Zhijin Zhang ◽  
Xingliang Jiang ◽  
Tian Liang
Keyword(s):  
Power Systems ◽  
Electric Fields ◽  
Particle Motion ◽  
Particle Diameter ◽  
Environmental Parameters ◽  
Composite Insulator ◽  
High Voltage Direct Current ◽  
Electrical Stress ◽  
Motion Characteristics ◽  
Dc Electric Fields

Pollution-induced flashover is a serious threat to the safe operation of power systems. With the development of High Voltage Direct Current (HVDC), it is necessary to study insulator contamination in DC electric fields. In this paper, the energized wind tunnel contamination test was conducted in order to systematically study the pollution ratio, k (ratio of non-soluble deposit density (NSDD) of a DC-energized condition to a non-energized condition), under different environmental parameters. Later, a two-dimensional contamination model of short samples of an HVDC composite insulator was established. The particle motion characteristics under different environmental parameters were then analyzed by the finite element method (FEM). The research results showed that—the DC electric field had an influence on particle motion but in different environments, the degree of influence was different. In addition, k was found to largely vary, with a variation in the environmental parameters. When the electrical stress (Es) increased from 0 to 70 kV/m, k increased gradually. However, when the wind speed (ws) increased, k experienced a decreasing trend. Finally, as the particle diameter (dp) decreased, k increased at first, followed by a decrease, and then again showed an increase. The results of the pollution ratio, k, for different environmental parameters are of great importance for guiding anti-pollution work in power systems.

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