scholarly journals Research on the Flow Characteristics of Sudden-Reduction Oil Tube

2015 ◽  
Vol 9 (1) ◽  
pp. 77-79 ◽  
Author(s):  
Zhibin Zhang ◽  
Chunxi Lin ◽  
Weiqiang Ye ◽  
An Wei ◽  
Leming Xiao ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Energy Loss ◽  
Flow Characteristics ◽  
Orifice Plate ◽  
Empirical Expression ◽  
Contraction Ratio ◽  
Region Length ◽  
Sudden Reduction

The backflow region length in sudden-reduction oil tube is not only closely associated with its energy loss, but is also closely related to the partition between orifice plate and plug. In this paper, the characteristics of backflow region length in sudden-reduction oil tube are researched. The results illustrated that backflow region length decreases with the increase in the contraction ratio. Moreover, when Reynolds number is more than 105, Reynolds number has little impact on backflow region length. Empirical expression about backflow region length in sudden-reduction oil tube is also discussed in this paper.

scholarly journals Research on Backflow Region Length of Sudden-Enlarge Oil Tube Flows

2014 ◽  
Vol 8 (1) ◽  
pp. 974-976
Author(s):  
Jiahong Wang ◽  
Wanzheng Ai
Keyword(s):  
Reynolds Number ◽  
Energy Loss ◽  
Empirical Expression ◽  
Contraction Ratio ◽  
Region Length

Sudden-enlarge tube has important applications in reality lives. The backflow region length in sudden-enlarge tube flows is closely related with its energy loss. In this paper, the characteristics of backflow region length in suddenenlarge oil tube flows are researched. The results show that backflow region length decreases with the increase of the contraction ratio; when Reynolds number is more than 105, Reynolds number have little impacts on backflow region length. Empirical expression about backflow region length is also obtained by fitting curve in this paper.

Numerical Simulation of Characteristics of Sudden Reduction Tube Flow Based on FLUENT

2011 ◽  
Vol 255-260 ◽  
pp. 3461-3465
Author(s):  
Wan Zheng Ai ◽  
Bai Gang Huang
Keyword(s):  
Reynolds Number ◽  
Energy Loss ◽  
Loss Coefficient ◽  
Experiment Data ◽  
Empirical Expression ◽  
Contraction Ratio ◽  
Flow Through ◽  
Spillway Tunnel ◽  
Theoretical Considerations ◽  
Sudden Reduction

Sudden reduction tube was always used in spillway tunnel, drainage pipes and so on. The energy loss coefficient of sudden reduction tube flows is an important index of sudden reduction tube. In the present paper, this coefficient and relative parameters, such as the contraction ratio and Reynolds number of the flow through sudden reduction tube, were analyzed by theoretical considerations, and their relationships were obtained by the numerical simulations. It could be concluded that the energy loss coefficient was mainly dominated by the contraction ratio. The less the contraction ratio is, the larger is the energy loss coefficient. When Reynolds number is more than 105, Reynolds number has little impact on it. An empirical expression, which was verified by comparison with other experiment data, was presented to calculate the energy loss coefficient of sudden reduction tube flows.

scholarly journals Correction and laboratory investigation for energy loss coefficient of square-edged orifice plate

2021 ◽  
Vol 104 (2) ◽  
pp. 003685042110185
Author(s):  
Ai Wanzheng ◽  
Zhu Pengfei
Keyword(s):  
Energy Loss ◽  
Model Experiment ◽  
Plate Thickness ◽  
Primary Objective ◽  
Loss Coefficient ◽  
Orifice Plate ◽  
Discharge Tunnel ◽  
Energy Dissipater ◽  
Contraction Ratio ◽  
Relative Errors

A lot of studies have shown that the hydraulic characteristics of orifice plate are mainly controlled by its contraction ratio, but the thickness of square-edged orifice plate also has many impacts on energy loss characteristics. The primary objective of this study was to investigated the effects of square-edged orifice plate thickness on energy loss characteristics. In this paper, the effects of square-edged orifice plate thickness on energy loss characteristics are investigated by numerical simulation using CFD. Orifice plate discharge tunnel is axial symmetric, two dimensional numerical simulations of orifice plate discharge tunnel flow was used. The equation (9) for calculating energy loss coefficient of square-edged orifice plate energy dissipater considering the influence of thickness is proposed. The results of the present research demonstrate that energy loss coefficient decreases with increase of the orifice plate thickness. The results of model experiment are consistence with the results calculated by using rectified equation in present paper. The CFD simulations and Model experiment for the flow through an orifice plate are carried out. For square-edged orifice plate energy dissipater, the relative orifice plate thickness T/D has remarkable impacts on its energy loss coefficient ξ. The Traditional equation (8) is corrected by numerical results. The equation (9) for calculating energy loss coefficient of square-edged orifice plate energy dissipater considering the influence of thickness is proposed and this equation is available in the condition of d/D = 0.4–0.8, T/D = 0.05–0.25, and Re > 105(Re is Reynolds number). Comparing with the physical model experimental data, the relative errors of equation (9) is smaller than 15%.

The Incipient Cavitation Number of Square-Edged Orifice Plate

2014 ◽  
Vol 568-570 ◽  
pp. 1702-1705
Author(s):  
Wei Jun Wang
Keyword(s):  
Reynolds Number ◽  
Plate Thickness ◽  
Cavitation Number ◽  
Orifice Plate ◽  
Simulation Methods ◽  
Contraction Ratio ◽  
Theoretical Considerations

In the present paper, the incipient cavitations number was analyzed by theoretical considerations. By using simulation methods, it could be regarded that the incipient cavitations number was mainly dominated by the contraction ratio of the orifice plate. The less the contraction ratio of the orifice plate is, the larger is the incipient cavitations number. The effects of orifice plate’ thickness on the incipient cavitations number was not obviously and could be neglected. When Reynolds number is more than 105, Reynolds number has little impact on the incipient cavitations number.

Numerical Investigation of 3-D Turbulent Flow in Orifice Plate within a Pipe

2015 ◽  
Vol 761 ◽  
pp. 27-31
Author(s):  
Mohamed Abed Alabas Siba ◽  
Wan Mohd Faizal Wan Mahmood ◽  
Mohd Zaki Nuawi ◽  
Rasidi Rasani
Keyword(s):  
Reynolds Number ◽  
Aspect Ratio ◽  
Turbulent Flow ◽  
Finite Volume ◽  
Numerical Study ◽  
Flow Characteristics ◽  
Reynolds Numbers ◽  
Orifice Plate ◽  
Navier Stokes ◽  
Volume Method

A numerical study of the turbulent flow in an orifice plate within a pipe is carried out by utilizing the Navier-Stokes (N-S) equations. The governing equations are solved using primitive variables with a finite volume method (FVM) and simulated using the finite volume based commercial CFD code ANSYS. The study investigates the influences of Reynolds numbers (Re = 5000, 10000, and 15000) and aspect ratio (β = 0.2, 0.3, and 0.5), on the flow characteristics, i.e. the velocity profile, the differential pressure, and the vorticity, and on the mechanical properties, i.e. the strain, the stress, and the total deformation of the flow around and beyond the orifice. It is found that as the Reynolds number increases, the flow velocity and the pressure increase. The vorticity images show a slightly different behavior. As the Reynolds number has its own effect on the results, it is also found that the aspect ratio affects the results more significantly. The flow patterns are presented for unsteady flow throughout the orifice plate at different values of the Reynolds number.

INCOMPRESSIBLE FLOW AT LOW REYNOLDS NUMBER IN A CONICAL ENTRANCE ORIFICE PLATE

2019 ◽  
Author(s):  
MARA NILZA ESTANISLAU REIS ◽  
Wender Oliveira ◽  
Pedro Américo Almeida Magalhães Júnior
Keyword(s):  
Reynolds Number ◽  
Incompressible Flow ◽  
Low Reynolds Number ◽  
Orifice Plate ◽  
Low Reynolds

Experimental Investigation of Effect of Tip Coolant Ejection on Internal Flow Characteristics Within a Realistic Blade Coolant Channel

2013 ◽  
Author(s):  
Jian Pu ◽  
Zhaoqing Ke ◽  
Jianhua Wang ◽  
Lei Wang ◽  
Hongde You
Keyword(s):  
Experimental Investigation ◽  
Reynolds Number ◽  
Pressure Drop ◽  
Turbine Blade ◽  
Flow Rate ◽  
Flow Characteristics ◽  
Reynolds Numbers ◽  
Flow Ratio ◽  
Lp Turbine ◽  
Mass Flow Ratio

This paper presents an experimental investigation on the characteristics of the fluid flow within an entire coolant channel of a low pressure (LP) turbine blade. The serpentine channel, which keeps realistic blade geometry, consists of three passes connected by a 180° sharp bend and a semi-round bend, 2 tip exits and 25 trailing edge exits. The mean velocity fields within several typical cross sections were captured using a particle image velocimetry (PIV) system. Pressure and flow rate at each exit were determined through the measurements of local static pressure and volume flow rate. To optimize the design of LP turbine blade coolant channels, the effect of tip ejection ratio (ER) from 180° sharp bend on the flow characteristics in the coolant channel were experimentally investigated at a series of inlet Reynolds numbers from 25,000 to 50,000. A complex flow pattern, which is different from the previous investigations conducted by a simplified square or rectangular two-pass U-channel, is exhibited from the PIV results. This experimental investigation indicated that: a) in the main flow direction, the regions of separation bubble and flow impingement increase in size with a decrease of the ER; b) the shape, intensity and position of the secondary vortices are changed by the ER; c) the mass flow ratio of each exit to inlet is not sensitive to the inlet Reynolds number; d) the increase of the ER reduces the mass flow ratio through each trailing edge exit to the extent of about 23–28% of the ER = 0 reference under the condition that the tip exit located at 180° bend is full open; e) the pressure drop through the entire coolant channel decreases with an increase in the ER and inlet Reynolds number, and a reduction about 35–40% of the non-dimensional pressure drop is observed at different inlet Reynolds numbers, under the condition that the tip exit located at 180° bend is full open.

Quantitative Experimental Study of SiO2-Water Nanofluids on Backward-Facing Step Flow under Low Reynolds Number

2018 ◽  
Vol 916 ◽  
pp. 221-225
Author(s):  
Ji Zu Lv ◽  
Liang Yu Li ◽  
Cheng Zhi Hu ◽  
Min Li Bai ◽  
Sheng Nan Chang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Reynolds Number ◽  
Volume Fraction ◽  
Pure Water ◽  
Experimental Studies ◽  
Flow Characteristics ◽  
Thermal Engineering ◽  
Heat Transfer Medium ◽  
Step Flow

Nanofluids is an innovative study of nanotechnology applied to the traditional field of thermal engineering. It refers to the metal or non-metallic nanopowder was dispersed into water, alcohol, oil and other traditional heat transfer medium, to prepared as a new heat transfer medium with high thermal conductivity. The role of nanofluids in strengthening heat transfer has been confirmed by a large number of experimental studies. Its heat transfer mechanism is mainly divided into two aspects. On the one hand, the addition of nanoparticles enhances the thermal conductivity. On the other hand, due to the interaction between the nanoparticles and base fluid causing the changes in the flow characteristics, which is also the main factor affecting the heat transfer of nanofluids. Therefore, a intensive study on the flow characteristics of nanofluids will make the study of heat transfer more meaningful. In this experiment, the flow characteristics of SiO2-water nanofluids in two-dimensional backward step flow are quantitatively studied by PIV. The results show that under the same Reynolds number, the turbulence of nanofluids is larger than that of pure water. With the increase of nanofluids volume fraction, the flow characteristics are constantly changing. The quantitative analysis proved that the nanofluids disturbance was enhanced compared with the base liquid, which resulting in the heat transfer enhancement.

Difference in Critical Reynolds Number Between Hagen-Poiseuille and Plane Poiseuille Flows

2001 ◽  
Author(s):  
Hidesada Kanda
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Poiseuille Flow ◽  
Average Velocity ◽  
Critical Reynolds Number ◽  
Inlet Section ◽  
Parallel Plates ◽  
Plane Poiseuille Flow ◽  
Contraction Ratio ◽  
Significant Difference

Abstract For plane Poiseuille flow, results of previous investigations were studied, focusing on experimental data on the critical Reynolds number, the entrance length, and the transition length. Consequently, concerning the natural transition, it was confirmed from the experimental data that (i) the transition occurs in the entrance region, (ii) the critical Reynolds number increases as the contraction ratio in the inlet section increases, and (iii) the minimum critical Reynolds number is obtained when the contraction ratio is the smallest or one, and there is no-shaped entrance or straight parallel plates. Its value exists in the neighborhood of 1300, based on the channel height and the average velocity. Although, for Hagen-Poiseuille flow, the minimum critical Reynolds number is approximately 2000, based on the pipe diameter and the average velocity, there seems to be no significant difference in the transition from laminar to turbulent flow between Hagen-Poiseuille flow and plane Poiseuille flow.

Flow and Energy Loss Downstream of Rectangular Sharp-Crested Weirs for Free and Submerged Flows

2021 ◽  
Author(s):  
Mahmud R. Amin ◽  
Nallamuthu Rajaratnam ◽  
David Z. Zhu
Keyword(s):  
Energy Loss ◽  
Flow Regime ◽  
Analytical Study ◽  
Flow Characteristics ◽  
Turbulent Jets ◽  
Flow Regimes ◽  
Impinging Jet ◽  
Relative Energy ◽  
Surface Flow ◽  
Upper Stage

Abstract This work presents an analytical study of the flow and energy loss immediately downstream of rectangular sharp-crested weirs for free and submerged flows, using the theory of plane turbulent jets and the analysis of some relevant studies. The flow regimes downstream of the sharp-crested weir is characterized as the impinging jet and surface flow regimes. Based on the flow characteristics and the downstream tailwater depths, each flow regime is further classified, and the relative energy loss equation is developed. It is found that significant energy loss occurs for the regime of supercritical flow and the upper stage of impinging jet flow. The energy loss for the submerged flow regime is minimal.

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