Extending Classical Friction Loss Modeling to Predict the Viscous Performance of Pumping Devices

2019 ◽  
Vol 141 (10) ◽  
Author(s):  
Abhay Patil ◽  
Wenjie Yin ◽  
Rahul Agarwal ◽  
Adolfo Delgado ◽  
Gerald Morrison
Keyword(s):  
Fluid Dynamics ◽  
Reynolds Number ◽  
Power Input ◽  
Flow Coefficient ◽  
Power Coefficient ◽  
Viscosity Effects ◽  
Computational Fluid Dynamics Cfd ◽  
Specific Speed ◽  
Using Data ◽  
Efficiency Data

The affinity law modified for viscosity effects is further extended to include the power input and efficiency. The power input and efficiency data generated using computational fluid dynamics (CFD) are utilized to represent dimensionless power coefficient and efficiency for the pump under consideration. The goal of modifying the affinity laws for power input is achieved by developing a new relationship where the power coefficient is modified by multiplying it by rotational Reynolds number raised to a power Π*Rew−Pat. This new relationship is then represented as a function of a modified flow coefficient ф*Rew−Mo. All the data collapse onto a single curve for varying values of the exponents Morrison number (Mo) and Patil number (Pat). Pat is further characterized as a function of flow regime and specific speed. The method also holds true for efficiency prediction, however, with different values of Mo and Pat. The proposed method is validated by using data collected from published literature.

Affinity Law Modified to Predict the Pump Head Performance for Different Viscosities Using the Morrison Number

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Abhay Patil ◽  
Gerald Morrison
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Flow Coefficient ◽  
Design Parameters ◽  
Sharp Change ◽  
Fluid Viscosity ◽  
Pump Head ◽  
Laminar And Turbulent Flow ◽  
Computational Fluid Dynamics Cfd ◽  
And Performance

The goal of this study is to provide pump users a simple means to predict a pump's performance change due to changing fluid viscosity. During the initial investigation, it has been demonstrated that pump performance can be represented in terms of the head coefficient, flow coefficient, and rotational Reynolds number with the head coefficient data for all viscosities falling on the same curve when presented as a function of ф*Rew−a. Further evaluation of the pump using computational fluid dynamics (CFD) simulations for wider range of viscosities demonstrated that the value of a (Morrison number) changes as the rotational Reynolds number increases. There is a sharp change in Morrison number in the range of 104<Rew<3*104 indicating a possible flow regime change between laminar and turbulent flow. The experimental data from previously published literature were utilized to determine the variation in the Morrison number as the function of rotational Reynolds number and specific speed. The Morrison number obtained from the CFD study was utilized to predict the head performance for the pump with known design parameters and performance from published literature. The results agree well with experimental data. The method presented in this paper can be used to establish a procedure to predict any pump's performance for different viscosities; however, more data are required to completely build the Morrison number plot.

CFD-BASED RESEARCH ON THE LOAD-BEARING CAPACITY OF ASYMMETRIC TEXTURE WITH DIFFERENT REYNOLDS NUMBER

2013 ◽  
Vol 20 (05) ◽  
pp. 1350043 ◽  
Author(s):  
YUNCAI ZHAO ◽  
LEI HAN
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Reynolds Number ◽  
Bearing Capacity ◽  
Two Dimensional ◽  
Hydrodynamic Load ◽  
Cfd Model ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Computational Fluid Dynamics Cfd

A two-dimensional computational fluid dynamics (CFD) model was developed to study the load-bearing capacity of asymmetric texture under the state of fluid lubrication. The effects of asymmetric parameter H and the Reynolds number Re on hydrodynamic load-bearing capacity of the oil film were discussed. It was found that a decrease in asymmetric parameter H may significantly improve the load-bearing capacity, but an increase in Reynolds number Re may reduce this effect. For example, with a Re at 20, the load-bearing capacity increases by 73.44% with the H varying from 4 to 0.2. However, with a Re at 160, it has only an increase of 4.68% at the same conditions. In addition, the numerical results also showed that the load-bearing capacity will increase with the increase of Re in certain texture.

Viscous Scaling Phenomena in Miniature Centrifugal Flow Cooling Fans: Theory, Experiments and Correlation

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
Patrick A. Walsh ◽  
Edmond J. Walsh ◽  
Ronan Grimes
Keyword(s):  
Reynolds Number ◽  
Scale Effects ◽  
Pressure Coefficient ◽  
Pressure Rise ◽  
Chord Length ◽  
Flow Coefficient ◽  
Power Coefficient ◽  
Small Scale ◽  
Cooling Fans ◽  
Novel Theory

This paper analyzes the scale effects that occur in miniature centrifugal flow fans and investigates the possibility of optimizing blade geometry so that performance can be enhanced. Such fans are typically employed in small scale heat sinks such as those used for processor cooling applications or in portable electronics. The specific design parameter varied is the blade chord length, and the resulting fan performance is gauged by examining the flow rate, pressure rise, and power consumption characteristics. The former two are measured using a BS 848 fan characterization rig and the latter, by directly measuring the power consumed. These characteristics are studied for three sets of scaled fans with diameters of 15 mm, 24 mm, and 30 mm, and each set considers six individual blade chord lengths. A novel theory is put forward to explain the anticipated effect of changing this parameter, and the results are analyzed in terms of the relevant dimensionless parameters: Reynolds number, chord length to diameter of fan ratio, flow coefficient, pressure coefficient, and power coefficient. When these characteristic parameters are plotted against the Reynolds number, similar trends are observed as the chord length is varied in all sets of scaled fans. The results show that the flow coefficient for all the miniature fans degrade at low Re values, but the onset of this degradation was observed at higher Re values for longer blade chord designs. Conversely, it was found that the pressure coefficient is elevated at low Re, and the onset Re for this phenomenon correlates well with the drop off in flow coefficient. Finally, the trend in power coefficient data is similar to that for the flow coefficient. The derived theory is used to correlate this data for which all data points fall within 6% of the correlation. Overall, the findings reported herein provide a good understanding of how changing the blade chord length affects the performance of miniature centrifugal fans; hence, providing fan designers with guidelines to aid in developing optimum blade designs, which minimize adverse scaling phenomena.

Quantification of Mixing in RIM Using a Non-Diffusive Two-Phase Flow Numerical Model

2011 ◽  
Vol 9 (1) ◽  
Author(s):  
Cláudio P. Fonte ◽  
Ricardo J. Santos ◽  
Madalena M. Dias ◽  
José Carlos B. Lopes
Keyword(s):  
Fluid Dynamics ◽  
Reynolds Number ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Linear Scale ◽  
Cfd Simulations ◽  
Two Phase ◽  
Vof Model ◽  
Mixing Chamber ◽  
Computational Fluid Dynamics Cfd

Mixing in RIM is made mainly by advective mechanisms, rather than diffusion. In this paper, the advective mechanisms that enable reducing the mixing scales down to the values required for the complete chemical reaction of the two monomers inside the RIM mixing chamber are identified and studied. From Computational Fluid Dynamics (CFD) simulations of non-diffusive two-phase flow using the Volume-of-Fluid (VOF) model, a linear scale of segregation is determined as a measure of the degree of mixing and the effect of the Reynolds number is studied.

Effects of Impeller Squealer Tip on Centrifugal Compressor Performance

2016 ◽  
Author(s):  
Riccardo Da Soghe ◽  
Cosimo Bianchini ◽  
Lorenzo Toni ◽  
Dante Tommaso Rubino
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Flow ◽  
Tip Clearance ◽  
Flow Coefficient ◽  
Performance Improvements ◽  
Positive Effects ◽  
Computational Fluid Dynamics Cfd ◽  
Compressor Performance ◽  
Load Conditions

This paper summarizes the main results sorted out from a Design of Experiment (DoE) based on a validated Computational Fluid Dynamics (CFD). Several tip recessed geometries applied to an unshrouded impeller were considered in conjunction with two tip clearance levels. The computations show that recessed tip geometries have positive effects when considering high flow coefficient values while in part-load conditions the gain is reduced. Starting from the results obtained when studying tip cavities, a single rim tip squealer geometry was then analysed: the proposed geometry leads to performance improvements for all the tested conditions considered in this work.

scholarly journals Investigating the Effect of Heterogeneous Hull Roughness on Ship Resistance Using CFD

2021 ◽  
Vol 9 (2) ◽  
pp. 202
Author(s):  
Soonseok Song ◽  
Yigit Kemal Demirel ◽  
Claire De Marco Muscat-Fenech ◽  
Tonio Sant ◽  
Diego Villa ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Reynolds Number ◽  
Shear Stress ◽  
Flow Characteristics ◽  
Cfd Simulations ◽  
Ship Resistance ◽  
Wigley Hull ◽  
Computational Fluid Dynamics Cfd ◽  
Good Agreement

Research into the effects of hull roughness on ship resistance and propulsion is well established, however, the effect of heterogeneous hull roughness is not yet fully understood. In this study, Computational Fluid Dynamics (CFD) simulations were conducted to investigate the effect of heterogeneous hull roughness on ship resistance. The Wigley hull was modelled with various hull conditions, including homogeneous and heterogeneous hull conditions. The results were compared against existing experimental data and showed a good agreement, suggesting that the CFD approach is valid for predicting the effect of heterogeneous hull roughness on ship resistance. Furthermore, the local distributions of the wall shear stress and roughness Reynolds number on the hull surface were examined to assess the flow characteristics over the heterogeneous hull roughness.

Effects of Impeller Squealer Tip on Centrifugal Compressor Performance

2016 ◽  
Vol 139 (3) ◽  
Author(s):  
Riccardo Da Soghe ◽  
Cosimo Bianchini ◽  
Dante Tommaso Rubino ◽  
Lorenzo Toni
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Flow ◽  
Tip Clearance ◽  
Flow Coefficient ◽  
Performance Improvements ◽  
Positive Effects ◽  
Computational Fluid Dynamics Cfd ◽  
Compressor Performance ◽  
Load Conditions

This paper summarizes the main results sorted out from a design of experiment (DoE) based on a validated computational fluid dynamics (CFD). Several tip recessed geometries applied to an unshrouded impeller were considered in conjunction with two tip clearance levels. The computations show that recessed tip geometries have positive effects when considering high-flow coefficient values, while in part-load conditions the gain is reduced. Starting from the results obtained when studying tip cavities, a single rim tip squealer geometry was then analyzed: the proposed geometry leads to performance improvements for all the tested conditions considered in this work.

A Study on Distributive Regularities of the Fluid Pressure in Elbow Pipes

2011 ◽  
Vol 366 ◽  
pp. 80-85 ◽  
Author(s):  
Xiao Yang Lu ◽  
Xiao Li Lu ◽  
Li Li Huang
Keyword(s):  
Fluid Dynamics ◽  
Reynolds Number ◽  
High Pressure ◽  
Spatial Distribution ◽  
Fluid Pressure ◽  
Qualitative Description ◽  
Axial Angle ◽  
Computational Fluid Dynamics Cfd ◽  
High Temperature High Pressure ◽  
Reliable Basis

This paper is a study on the distributive regularities of dimensionless pressure in elbow pipes by dimensional and qualitative analyzing methods. The qualitative description method of fluid flow such as 90° elbow pipe is obtained. With Computational Fluid Dynamics (CFD), the effect of a number of dimensionless parameters such as the non-dimensional curvature, Reynolds number, dimensionless axial angle α and annular angle β and other factors on the spatial distribution of pressure inside the elbow are analyzed and discussed in detail. This paper not only provides theoretical and numerical methods for understanding the dynamic behavior of the fluid in the elbow pipes, but also provides the reliable basis for designing thickness of elbow pipes with high temperature, high pressure and high velocity.

Swirling Flow Through Venturi Tubes of Convergent Angle 10.5° and 21°

2006 ◽  
Author(s):  
Jeff Gibson ◽  
Michael Reader-Harris
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Reynolds Number ◽  
Swirling Flow ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Through ◽  
Good Agreement

Computational Fluid Dynamics (CFD) was used to compute the effect of two bends in perpendicular planes on the performance of 4-inch Venturi tubes with β = 0.4, 0.6 and 0.75 for water at a Reynolds number of 350,000 and at various distances from the bend. Two types of Venturi tubes were analysed, the first having a standard convergent angle of 21°, the second having a non-standard convergent angle of 10.5°. Good agreement with experiment was obtained. Swirling axisymmetric flows were computed to help interpret experimental data.

A Transient Computational Fluid Dynamics, Phase Modulated, Multifrequency Approach for Impeller Rotordynamic Forces

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Farzam Mortazavi ◽  
Alan Palazzolo
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Condition ◽  
American Petroleum Institute ◽  
Rotating Stall ◽  
Path Model ◽  
Flow Coefficient ◽  
Specific Speed ◽  
Rotordynamic Forces ◽  
Force Data

Modern high performance turbomachines frequently operate in supercritical condition above their first critical speed, rendering these machines prone to rotordynamic instability. The American Petroleum Institute (API) standards require advanced simulation models for level II stability analysis of impellers. Such data are then incorporated into rotor-bearing vibration response models. Despite recent advancements in high fidelity, general modeling (i.e., three-dimensional viscous transient nonaxisymmetric model) of closed impeller rotordynamic forces, no such general model is available for open impellers, especially the centrifugal type. This paper extends the transient computational fluid dynamics (CFD) model previously used for closed impellers to open impellers. The recent model uses a phase modulated, multifrequency approach for enhanced computational efficiency and robustness. Results are validated against literature experiments at design and off-flow condition. The model is further applied to a spectrum of specific speeds to extract the dimensionless rotordynamic forces for each class of impellers at design and off-flow conditions. Such dimensionless force data can be used to estimate the rotordynamic forces of impellers with similar specific speed. Depending on specific speed and the relative flow coefficient, many of these impellers are found to be excited by forward or backward whirl. Strong interaction with rotating stall typically appears in the force data at off-flow condition. Simulations of the isolated leakage path model (ILPM) for equivalent closed impellers reveal similar bumps and dips associated with highly swirling inflow which naturally occurs at part flow condition.

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