Integral Pumping Devices for Dual Mechanical Seals: Experiments and Numerical Simulations

2014 ◽  
Vol 137 (2) ◽  
Author(s):  
H. A. Warda ◽  
E. M. Wahba ◽  
E. A. Selim
Keyword(s):  
Numerical Simulations ◽  
Rotational Speed ◽  
Numerical Study ◽  
Axial Flow ◽  
Radial Clearance ◽  
Inlet Temperature ◽  
Mechanical Seals ◽  
Outlet Port ◽  
Computational Fluid Dynamics Cfd ◽  
Multiple Reference

An experimental and numerical investigation is carried out to evaluate the performance of alternative pumping ring designs for dual mechanical seals. Both radial-flow and axial-flow pumping rings are considered in the present study. An experimental setup is constructed, and appropriate instrumentation are employed to measure the pressure, temperature, and flow rate of the barrier fluid. A parametric study is carried out to investigate the effect of pump rotational speed, barrier fluid accumulator pressure, and barrier fluid inlet temperature on the performance of the pumping rings. Experiments are also used to evaluate the effect of different geometric parameters such as the radial clearance between the pumping ring and the surrounding gland, and the outlet port orientation. Moreover, a numerical study is conducted to simulate the flow field for the radial pumping ring designs under different operating parameters. The computational fluid dynamics (CFD) model implements a multiple reference frame (MRF) technique, while turbulence is modeled using the standard k-epsilon model. Numerical simulations are also used to visualize the flow of the barrier fluid within the dual seal cavity. Present results indicate that the pump rotational speed and the orientation of the outlet port have a significant effect on the performance of the pumping ring. On the other hand, the effects of barrier fluid accumulator pressure and inlet temperature are minimal on the performance. The study also shows that reducing the radial clearance between the rotating ring and the stationary outer gland would significantly improve the performance of axial pumping rings. Moreover, comparisons between the computational and experimental results show good agreement for pumping ring configurations with tangential outlet (TO) ports and at moderate rotational speeds.

Integral Pumping Devices for Dual Mechanical Seals: Hydraulic Performance Generalization Using Dimensional Analysis

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Hassan A. Warda ◽  
Ihab G. Adam ◽  
Ahmed B. Rashad ◽  
Muhannad W. Gamal-Aldin
Keyword(s):  
Rotational Speed ◽  
Radial Flow ◽  
Axial Flow ◽  
Hydraulic Performance ◽  
American Petroleum Institute ◽  
Mechanical Seals ◽  
Characteristic Curves ◽  
Outlet Port ◽  
Operation Conditions ◽  
Generalized Curves

An experimental study is carried out investigating hydraulic performance for various designs of dual-mechanical-seal cartridges with integral pumping-rings. The tested devices are classified into two main families: radial-flow and axial-flow. The radial-flow family utilizes the modified-paddle-wheel (MPW) pumping ring with either a radial or a tangential oriented cartridge outlet port, while the axial-flow family utilizes the pumping scroll (PS) pumping ring in the following cartridge-geometries: single-pumping-scroll (SS) and double-pumping-scroll (DS); as both types can be of either a radial or a tangential outlet port; and of an internal clearance value complying with American Petroleum Institute (API) 682 standard or smaller clearance. An experimental setup is constructed, and appropriate instrumentation is employed to measure inlet pressure, outlet pressure, rotational speed, and barrier fluid flow rate acquiring flow-head characteristic curves. Moreover, empirical generalized characteristic curves are deduced from experimental observations obtained from the present study and previous companion work. The generalized curves can be employed in estimating pumping ring performance for a different size or other operation conditions such as varying rotational speed or fluid type. They can be also utilized to validate numerical simulations for geometrically similar designs.

Numerical Characterization of Hot Gas Ingestion Through Turbine Rim Seals

2016 ◽  
Author(s):  
Riccardo Da Soghe ◽  
Cosimo Bianchini ◽  
Carl M. Sangan ◽  
James A. Scobie ◽  
Gary D. Lock
Keyword(s):  
Flow Rate ◽  
Numerical Study ◽  
Axial Flow ◽  
Radial Clearance ◽  
Buffering Effect ◽  
Hot Gas ◽  
Numerical Predictions ◽  
Wide Range ◽  
Thermal Buffering

This paper deals with a numerical study aimed at the characterization of hot gas ingestion through turbine rim seals. The numerical campaign focused on an experimental facility which models ingress through the rim seal into the upstream wheel-space of an axial-turbine stage. Single-clearance arrangements were considered in the form of axial- and radial-seal gap configurations. With the radial-seal clearance configuration, CFD steady-state solutions were able to predict the system sealing effectiveness over a wide range of coolant mass flow rates reasonably well. The greater insight of flow field provided by the computations illustrates the thermal buffering effect when ingress occurs: for a given sealing flow rate, the effectiveness on the rotor was significantly higher than that on the stator due to the axial flow of hot gases from stator to rotor caused by pumping effects. The predicted effectiveness on the rotor was compared with a theoretical model for the thermal buffering effect showing good agreement. When the axial-seal clearance arrangement is considered, the agreement between CFD and experiments worsens; the variation of sealing effectiveness with coolant flow rate calculated by means of the simulations display a distinct kink. It was found that the “kink phenomenon” can be ascribed to an over-estimation of the egress spoiling effects due to turbulence modelling limitations. Despite some weaknesses in the numerical predictions, the paper shows that CFD can be used to characterize the sealing performance of axial- and radial-clearance turbine rim seals.

Numerical Characterization of Hot-Gas Ingestion Through Turbine Rim Seals

2016 ◽  
Vol 139 (3) ◽  
Author(s):  
Riccardo Da Soghe ◽  
Cosimo Bianchini ◽  
Carl M. Sangan ◽  
James A. Scobie ◽  
Gary D. Lock
Keyword(s):  
Flow Rate ◽  
Numerical Study ◽  
Axial Flow ◽  
Radial Clearance ◽  
Buffering Effect ◽  
Hot Gas ◽  
Numerical Predictions ◽  
Wide Range ◽  
Thermal Buffering

This paper deals with a numerical study aimed at the characterization of hot-gas ingestion through turbine rim seals. The numerical campaign focused on an experimental facility which models ingress through the rim seal into the upstream wheel-space of an axial-turbine stage. Single-clearance arrangements were considered in the form of axial- and radial-seal gap configurations. With the radial-seal clearance configuration, computational fluid dynamics (CFD) steady-state solutions were able to predict the system sealing effectiveness over a wide range of coolant mass flow rates reasonably well. The greater insight of flow field provided by the computations illustrates the thermal buffering effect when ingress occurs: For a given sealing flow rate, the effectiveness on the rotor was significantly higher than that on the stator due to the axial flow of hot gases from stator to rotor caused by pumping effects. The predicted effectiveness on the rotor was compared with a theoretical model for the thermal buffering effect showing good agreement. When the axial-seal clearance arrangement is considered, the agreement between CFD and experiments worsens; the variation of sealing effectiveness with coolant flow rate calculated by means of the simulations displays a distinct kink. It was found that the “kink phenomenon” can be ascribed to an overestimation of the egress spoiling effects due to turbulence modeling limitations. Despite some weaknesses in the numerical predictions, the paper shows that CFD can be used to characterize the sealing performance of axial- and radial-clearance turbine rim seals.

scholarly journals Numerical Study on the Characteristics of Pressure Fluctuations in an Axial-Flow Water Pump

2014 ◽  
Vol 6 ◽  
pp. 565061 ◽  
Author(s):  
Zhi-Jun Shuai ◽  
Wan-You Li ◽  
Xiang-Yuan Zhang ◽  
Chen-Xing Jiang ◽  
Feng-Chen Li
Keyword(s):  
Numerical Simulations ◽  
Numerical Study ◽  
Pressure Fluctuations ◽  
Three Dimensional ◽  
Axial Flow ◽  
Rotation Frequency ◽  
Dominant Frequency ◽  
Water Pump ◽  
Flow Induced Vibration ◽  
Impeller Blade

Flow induced vibration due to the dynamics of rotor-stator interaction in an axial-flow pump is one of the most damaging vibration sources to the pump components, attached pipelines, and equipment. Three-dimensional unsteady numerical simulations were conducted on the complex turbulent flow field in an axial-flow water pump, in order to investigate the flow induced vibration problem. The shear stress transport (SST) k-ω model was employed in the numerical simulations. The fast Fourier transform technique was adopted to process the obtained fluctuating pressure signals. The characteristics of pressure fluctuations acting on the impeller were then investigated. The spectra of pressure fluctuations were predicted. The dominant frequencies at the locations of impeller inlet, impeller outlet, and impeller blade surface are all 198 Hz (4 times of the rotation frequency 49.5 Hz), which indicates that the dominant frequency is in good agreement with the blade passing frequency (BPF). The first BPF dominates the frequency spectrum for all monitoring locations inside the pump.

scholarly journals Transmission Coefficient Analysis of Notched Shape Floating Breakwater Using Volume of Fluid Method: A Numerical Study

Kapal ◽  
2021 ◽  
Vol 18 (1) ◽  
pp. 41-50
Author(s):  
Asfarur Ridlwan ◽  
Haryo Dwito Armono ◽  
Shade Rahmawati ◽  
Tuswan Tuswan
Keyword(s):  
Numerical Simulations ◽  
Transmission Coefficient ◽  
Numerical Study ◽  
Soil Conditions ◽  
Current Application ◽  
Floating Breakwater ◽  
Computational Fluid Dynamics Cfd ◽  
Comparative Results ◽  
3D Software ◽  
Tidal Variations

As one of the coastal structures, breakwaters are built to protect the coastal area against waves. The current application of breakwaters is usually conventional breakwaters, such as the rubble mound type. Climate change, which causes tidal variations, sea level height, and unsuitable soil conditions that cause large structural loads, can be solved more economically by employing floating breakwater. In this study, numerical simulations will be conducted by exploring the optimum floating breakwater notched shapes from the Christensen experiment. The comparison of three proposed floating breakwater models, such as square notch (SQ), circular notch (CN), and triangular notch (VN), is compared with standard pontoon (RG) to optimize the transmission coefficient value is analyzed. Numerical simulations are conducted using Computational Fluid Dynamics (CFD) based on the VOF method with Flow 3D Software. Compared to the experimental study, the RG model's validation shows a good result with an error rate of 8.5%. The comparative results of the floating breakwater models are found that the smaller the transmission coefficient value, the more optimal the model. The SQ structure has the smallest transmission coefficient of 0.6248. It can be summarized that the SQ model is the most optimal floating breakwater structure.

Numerical Investigation Into Non-Synchronous Vibrations of Axial Flow Compressors by the Resonant Tip Clearance Flow

2009 ◽  
Author(s):  
Martin Drolet ◽  
Jean Thomassin ◽  
Huu Duc Vo ◽  
Njuki W. Mureithi
Keyword(s):  
Experimental Data ◽  
Numerical Study ◽  
Axial Flow ◽  
Numerical Results ◽  
Tip Clearance ◽  
Inlet Temperature ◽  
Compressor Blades ◽  
Turbine Engine ◽  
Tip Clearance Flow ◽  
Clearance Flow

This work investigates Non-Synchronous Vibrations (NSV) encountered in a turbine engine axial flow compressor using a Computational Fluid Dynamics (CFD) approach. It has been proposed that the resonance of the tip clearance flow in compressor blades could be the physical mechanism behind NSV. This work’s emphasis is on being able to computationally capture this resonance and predict the critical NSV speed using CFD. This would considerably reduce the costs involved in future hardware design and testing. The model uses the same compressor blade geometry on which experimental validation of the proposed NSV theory was conducted. The flow interaction with blade vibratory motion is modeled using a moving mesh capability and a SAS-SST turbulence model is used for computation. A review of the proposed theory on NSV is done. The CFD model is first verified with experimental data and then characterized to ensure that the simulations are conducted at the proper NSV conditions, in order to assess the resonance of the tip clearance flow. Evidence of this resonance behavior is presented and critical NSV speeds are identified based on numerical results for two different inlet temperature cases and are validated against experimental data. Further study of the actual flow structure associated with NSV is done. Additional remarks on the numerical results are discussed. An iterative design methodology to account for NSV is also proposed based on the current numerical study.

AN INNOVATIVE METHOD FOR GENERATING PULSATILE BLOOD FLOW VIA AN AXIAL VENTRICULAR ASSIST DEVICE

2015 ◽  
Vol 27 (03) ◽  
pp. 1550026
Author(s):  
Hanieh Niroomand-Oscuii ◽  
Mojtaba Koochaki ◽  
Erfan Nammakie
Keyword(s):  
Pulsatile Flow ◽  
Rotational Speed ◽  
Axial Flow ◽  
Ventricular Assist Devices ◽  
Shear Stresses ◽  
Assist Device ◽  
Ventricular Assist ◽  
Innovative Method ◽  
Margin Of Safety ◽  
Computational Fluid Dynamics Cfd

In recent years, ventricular assist devices (VAD) have received a worldwide admissibility and have become the unrivalled tools for replacing a failed heart. Most of the newer generations of these devices, including second and third generations, are designed to produce non-pulsatile flow at constant rotational speed. Here, we have proposed the design of a VAD, which although is an axial flow type, is able to produce pulsatile flow; and this has come through by changing the rotational speed of the impeller of the pump. This pump, which has an output analogous to cardiac output, is able to produce a flow rate of approximately 6 L per minute. Designing of this pump is based on turbomachinery theories and applying computational fluid dynamics (CFD) methods. The proposed pattern of the changes of rotational speed is trapezoidal and consists of four phases. Studies of the shear stresses imposed on the blood within the pump have shown that there has been an acceptable margin of safety for this pump in terms of blood injuries such as hemolysis and thrombosis.

scholarly journals Numerical Analysis of Thermochemical Nonequilibrium Flows in a Model Scramjet Engine

Energies ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 606
Author(s):  
Seoeum Han ◽  
Sangyoon Lee ◽  
Bok Jik Lee
Keyword(s):  
Numerical Simulations ◽  
Test Section ◽  
Thermal Equilibrium ◽  
Fuel Injection ◽  
Numerical Study ◽  
Three Dimensional ◽  
Reservoir Conditions ◽  
Nonequilibrium States ◽  
Computational Fluid Dynamics Cfd ◽  
Inflow Conditions

This numerical study was conducted to investigate the flow properties in a model scramjet configuration of the experiment in the T4 shock tunnel. In most numerical simulations of flows in shock tunnels, the inflow conditions in the test section are determined by assuming the thermal equilibrium of the gas. To define the inflow conditions in the test section, the numerical simulation of the nozzle flow with the given nozzle reservoir conditions from the experiment is conducted by a thermochemical nonequilibrium computational fluid dynamics (CFD) solver. Both two-dimensional (2D) and three-dimensional (3D) numerical simulations of the flow in a model scramjet were conducted without fuel injection. Simulations were performed for two types of inflow conditions: one for thermochemical nonequilibrium states obtained from the present nozzle simulation and the other for the data available using the thermal equilibrium and chemical nonequilibrium assumptions. The four results demonstrate the significance of the modelling approach for choosing between 2D or 3D, and thermal equilibrium or nonequilibrium.

Using Ansys for Design and Numerical Study of a Specific Fixed Wing UAV

2018 ◽  
Vol 55 (4) ◽  
pp. 652-657 ◽  
Author(s):  
Gabriel Murariu ◽  
Razvan Adrian Mahu ◽  
Adrian Gabriel Murariu ◽  
Mihai Daniel Dragu ◽  
Lucian P. Georgescu ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Unmanned Aerial Vehicle ◽  
Numerical Study ◽  
Flight Time ◽  
Cluster System ◽  
Numerical Results ◽  
Operational Performance ◽  
Gliding Flight ◽  
Aerial Vehicle ◽  
Constant Altitude

This article presents the design of a specific unmanned aerial vehicle UAV prototype own building. Our UAV is a flying wing type and is able to take off with a little boost. This system happily combines some major advantages taken from planes namely the ability to fly horizontal, at a constant altitude and of course, the great advantage of a long flight-time. The aerodynamic models presented in this paper are optimized to improve the operational performance of this aerial vehicle, especially in terms of stability and the possibility of a long gliding flight-time. Both aspects are very important for the increasing of the goals� efficiency and for the getting work jobs. The presented simulations were obtained using ANSYS 13 installed on our university� cluster system. In a next step the numerical results will be compared with those during experimental flights. This paper presents the main results obtained from numerical simulations and the obtained magnitudes of the main flight coefficients.

Liver Radioembolization: An Analysis of Parameters that Influence the Catheter-Based Particle-Delivery via CFD

2020 ◽  
Vol 27 (10) ◽  
pp. 1600-1615 ◽  
Author(s):  
Jorge Aramburu ◽  
Raúl Antón ◽  
Alejandro Rivas ◽  
Juan C. Ramos ◽  
Bruno Sangro ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Particle Distribution ◽  
Numerical Approach ◽  
Radioactive Microspheres ◽  
Tumor Bearing ◽  
Hemodynamic Pattern ◽  
Valuable Treatment ◽  
Catheter Tip ◽  
Radiation Induced ◽  
Computational Fluid Dynamics Cfd

Radioembolization (RE) is a valuable treatment for liver cancer. It consists of administering radioactive microspheres by an intra-arterially placed catheter with the aim of lodging these microspheres, which are driven by the bloodstream, in the tumoral bed. Even though it is a safe treatment, some radiation-induced complications may arise. In trying to detect or solve the possible incidences that cause nontarget irradiation, simulating the particle- hemodynamics in hepatic arteries during RE by computational fluid dynamics (CFD) tools has become a valuable approach. This paper reviews the parameters that influence the outcome of RE and that have been studied via numerical simulations. In this numerical approach, the outcome of RE is regarded as successful if particles reach the artery branches that feed tumor-bearing liver segments. Up to 10 parameters have been reviewed. The variation of each parameter actually alters the hemodynamic pattern in the vicinities of the catheter tip and locally alters the incorporation of the particles into the bloodstream. Therefore, in general, the local influences of these parameters should result in global differences in terms of particle distribution in the hepatic artery branches. However, it has been observed that under some (qualitatively described) appropriate conditions where particles align with blood streamlines, the local influence resulting from a variation of a given parameter vanishes and no global differences are observed. Furthermore, the increasing number of CFD studies on RE suggests that numerical simulations have become an invaluable research tool in the study of RE.

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