Specific momentum of a flow in the minimal cross section of a laval nozzle and in the outlet cross section of a contracting nozzle

1977 ◽  
Vol 11 (1) ◽  
pp. 171-174 ◽  
Author(s):  
A. N. Kraiko ◽  
V. E. Sokolov
Keyword(s):  
Cross Section ◽  
Laval Nozzle ◽  
Outlet Cross Section ◽  
Minimal Cross Section ◽  
Specific Momentum

scholarly journals FLUID FLOW STUDY IN VARIOUS SHAPES AND SIZES OF HORIZONTAL AXIS SEA CURRENT TURBINE

SINERGI ◽  
2021 ◽  
Vol 25 (3) ◽  
pp. 289
Author(s):  
Wulfilla Maxmilian Rumaherang ◽  
Jonny Latuny
Keyword(s):  
Flow Velocity ◽  
Cross Section ◽  
Cross Sections ◽  
Discharge Coefficient ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Flow Speed ◽  
Diameter Ratio ◽  
Power Coefficient ◽  
Outlet Cross Section

The ducted tidal turbine models have been developed to utilize the conversion of the kinetic energy on ocean currents. The research in refining the turbine characteristics has been carried out by modifying the turbine’s shape and size. This study investigated flow characteristics in the meridional section of five ducted turbines models for seawater flow with velocity U0 = 1.5 m/s. The ducted turbine design and construction have five different impeller house diameters and fixed inlet and outlet diameters. The potential energy flow theory and experimental data are used to analyze the flow characteristics of the model. The results show that flow velocity in the x-direction at the inlet and outlet cross-section is getting smaller, reducing the impeller house cross section. Each impeller house size reduction increases the flow speed in the impeller house cross-section and also pressure on all other cross-sections tested. In the inlet area, the increased pressure indicates a decrease in speed flow and discharge coefficient value. The discharge coefficient value decreases from CQ = 0.9 at the diameter ratio of dr = 1 to CQ = 0.56 at the diameter ratio of dr = 0.375. The maximum value of power coefficient was determined at dr = 0,61÷0.73 or dr = 0.69 which is equivalent to average internal flow velocity Vr =2.0÷2.6 m/s and the static pressure ps = 97.1÷ 94.4 kPa. At the ratio value of D0/D2 = 0.83, the optimal diameter ratio dropt=0,61÷0.73 is in line with the duct model of case 3 and case 4, but it may be determined solely as for case 4.

Development of a CFD-Based Coal Pipe Design Tool

2005 ◽  
Author(s):  
Gengxun Huang ◽  
Kenneth M. Bryden
Keyword(s):  
Power Plant ◽  
Cross Section ◽  
Small Region ◽  
Design Tool ◽  
Plant Performance ◽  
Design Stage ◽  
Radius Of Curvature ◽  
Outlet Cross Section ◽  
Curved Pipe ◽  
Pipe Cross Section

In a coal-fired power plant, pulverized coal, using air as a transport medium, is pneumatically transported toward different burner nozzles by splitting the large pipe into small pipes through bifurcators or trifurcators. The combustion efficiency of the burner is dependent on matching the air and coal in these pipes. Increasingly tight emission standards also make the balance of air and coal a very critical factor for the success of the power plant. Coal roping occurs when the gas-solid flow passes through a curved pipe. The momentum of the particles carries them to the outside of the wall, concentrating in a small region. Therefore, the particle concentration in this small region is much higher than the other part of the pipe cross-section. Coal roping upstream of a coal distributor (bifurcator) can create a significant imbalance in coal loading in the split between the two branches. This can significantly impact plant performance and increase NOx production. Previous research [2] has shown that coal rope characteristics depend on many parameters; the geometry (i.e., elbow radius of curvature-to-pipe diameter ratio, pipe orientation, orifice opening, and the locations of orifices) of the coal pipe, which is determined at the design stage, will strongly affect the coal distribution in the outlet of coal pipes. This characteristic of coal roping indicates that optimizing the pipe geometry may be helpful in getting a more uniform coal distribution at the pipe’s outlet cross-section and minimizing the problems caused by imbalance between burners. In this paper, we present the CFD-based coal pipeline design tool to achieve the evenly distributed coal particle distribution across the pipe cross-section.

CFD modeling of slurry flow erosion wear rate through mitre pipe bend

2022 ◽  
pp. 095440622110263
Author(s):  
Om Parkash ◽  
Arvind kumar ◽  
Basant Singh Sikarwar
Keyword(s):  
Wear Rate ◽  
Cross Section ◽  
Erosive Wear ◽  
Cfd Modeling ◽  
Phase Method ◽  
Solid Concentration ◽  
Erosion Wear ◽  
Pipe Bend ◽  
Outlet Cross Section ◽  
Wide Range

Erosive wear caused by particulates slurry is one of the major concerns in the pipe bend which may results in the failure of the pipe flow system. In the present work, erosion wear rate through mitre pipe bend caused by silica sand particulates slurry has been investigated using ANSYS Fluent code. The solid spherical particulates of size 125 µm and 250 µm having density of 2650 Kg/m3, were tracked to compute the erosion wear rate using Discrete Phase Method (DPM) model. The particulates were tracked using Eulerian-Lagrange approach along with k-ɛ turbulent model for continuous fluid phase. The silica particulates were injected at solid concentration of 5% and 10% (by weight) from the pipe inlet surface for wide range of velocities viz. 1–8 ms−1. The erosion wear rate was computed through four computational erosion models viz. Generic, Oka, Finnie and Mclaury. Furthermore, the outcomes obtained through Generic models are verified through existing experimental data in the literture. Moreover, the results of DPM concentration, turbulence intensity and particle tracking were predicted to analyze the secondary flow behaviour through the bend cross section. Finally, the effect of particulate size, solid concentration and flow velocity were discussed on erosion wear rate through bend cross section. The findings show that the locality of maximum erosive wear is positioned at the extrados of the bend outlet cross section. Additionally, it is found that Mclaury model offers higher erosion rate as compared to the other models and provides benchmark for designing the slurry pipeline system.

scholarly journals Optimal Design for an Extruder Head Runner Based on Response Surface Method and Simulated Annealing Algorithm

2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
Haichao Zhou ◽  
Zhen Jiang ◽  
Wenchao Li ◽  
Guolin Wang ◽  
Yongjie Tu
Keyword(s):  
Simulated Annealing ◽  
Response Surface ◽  
Cross Section ◽  
Response Surface Model ◽  
Iteration Algorithm ◽  
Surface Model ◽  
Structure Parameters ◽  
Key Factors ◽  
Outlet Cross Section ◽  
Runner Design

The head runner of a rubber extruder is important for controlling rubber flow and improving extrudate quality. To clarify the effect of the structure parameters of the head runner of a doubleplex tread extruder on extrudate quality and obtain high-quality rubber extrusions, a finite element model of the down head runner was established. The extrusion process was analyzed through numerical simulations, wherein the Bird–Carreau constitutive equation and Navier slip law were used along with some computational methods, such as quadratic interpolation of velocity and linear interpolation of pressure and viscosity. The Newton iteration algorithm was used for numerical calculations. The mean-square deviation of velocity (SDV) of rubber flow in the outlet cross section was selected as the evaluation objective. A Placket–Burman design was used to select three key factors—angles A and B and outlet width D—from among eight runner structure parameters affecting the velocity variance. By using central composite design (CCD), the quadratic response surface model using the three key factors was established, and the influence law of a combination of the three key factors on SDV was obtained. The response surface model was optimized using the simulated annealing (SA) algorithm, and the optimal key factors of the head runner were obtained. The optimal runner design realizes a more uniform velocity distribution in the outlet cross section. Furthermore, a comparison of the simulated flow velocities of the original and optimal head runners at different inlet flow ratios and temperatures indicates that the optimal head runner flow velocity improves the extrusion quality. Thus, an optimal runner with optimal key factors was manufactured. Test results of the rubber flow state indicated that the flow is regular and that warping disappears. The proposed optimization strategy can be used practically for improving the head runner design, shortening the product development cycle, and reducing the production cost.

Multiple Submucosal Out-Fracture of the Inferior Turbinates: Evaluation of the Results by Acoustic Rhinometry

1996 ◽  
Vol 10 (6) ◽  
pp. 387-392 ◽  
Author(s):  
F. Márquez ◽  
C. Cenjor ◽  
R. Gutierrez ◽  
J. Sanabria
Keyword(s):  
General Anesthesia ◽  
Cross Section ◽  
Nasal Obstruction ◽  
Acoustic Rhinometry ◽  
Control Group ◽  
Endoscopic Evaluation ◽  
Cross Section Area ◽  
Section Area ◽  
Minimal Cross Section ◽  
Made In

A multiple submucosal out-fracture of the inferior turbinates was made in 21 patients with nasal obstruction due to hypertrophy of the inferior turbinates. Before surgery, an endoscopic evaluation and an acoustic rhinometry was performed in all the cases. The operation was done under general anesthesia and bilaterally in all the patients. Three months after surgery, a postoperative acoustic rhinometry was done and an increase of the minimal cross-section area was achieved in all the cases. Acoustic rhinometry performed in 100 normal cases was used as a control group.

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