scholarly journals The Influence of Bulb Position on Hydraulic Performance of Submersible Tubular Pump Device

2021 ◽  
Vol 9 (8) ◽  
pp. 831
Author(s):  
Zhuangzhuang Sun ◽  
Jie Yu ◽  
Fangping Tang
Keyword(s):  
Entropy Production ◽  
Large Scale ◽  
Experimental Testing ◽  
Guide Vane ◽  
Outer Wall ◽  
Hydraulic Performance ◽  
Hydraulic Loss ◽  
Optimized Design ◽  
Outlet Channel ◽  
Wall Area

In order to study the influence of the position of the bulb on the hydraulic performance of asubmersible tubular pump device, based on a large-scale pumping station, two schemes—involving a front-mounted bulb and a rear-mounted bulb, respectively—were designed. The front-mounted scheme uses the GL-2008-03 hydraulic model and its conventional guide vane, while the rearmounted scheme uses the optimized design of a diffuser vane. The method of combining numerical simulation and experimental testing was used to analyze the differences between the external and internal characteristics of the two schemes. The results show that, under the condition of reasonable diffusion guide vane design, the efficiency under the rear-mounted scheme is higher than that under the front-mounted scheme, where the highest efficiency difference is about 1%. Although the frontmounted bulb scheme reduces the hydraulic loss of the bulb section, the placement of the bulb on the water inlet side reduces the flow conditions of the impeller. Affected by the circulation of the guide vane outlet, the hydraulic loss of the outlet channel is greater than the rear-mounted scheme. The bulb plays a rectifying function when the bulb is placed behind, which greatly eliminates the annular volume of the guide vane outlet, and the water outlet channel has a smaller hydraulic loss. In the front-mounted scheme, the water flow inside the outlet channel squeezes to the outer wall, causing higher entropy production near the outer wall area. The entropy production of the rear-mounted scheme is mainly in the bulb section and the bulb support. This research can provide reference for the design and form selection of a submersible tubular pump device, which has great engineering significance.

Influence of Guide Ring on Energy Loss in a Multistage Centrifugal Pump

2018 ◽  
Vol 141 (6) ◽  
Author(s):  
Ren Yun ◽  
Zhu Zuchao ◽  
Wu Denghao ◽  
Li Xiaojun
Keyword(s):  
Energy Loss ◽  
Entropy Production ◽  
Evaluation Method ◽  
Guide Vane ◽  
Load Flow ◽  
Hydraulic Loss ◽  
Pump Efficiency ◽  
Centrifugal Pumps ◽  
Multistage Pump ◽  
Guide Ring

Multistage centrifugal pumps are highly efficient and compact in structure. Pump efficiency can be improved by an effective understanding of hydraulic behavior and energy loss, however, the traditional hydraulic loss evaluation method does not readily reveal the specific locations of energy loss in the pump. In this study, a guide ring was imposed in multistage pumps, and an entropy production theory was applied to investigate irreversible energy loss of a multistage pump with and without guide ring. Detailed distributions of energy losses in the pumps were calculated to determine the respective entropy production rates (EPRs). The EPR values as calculated are in close accordance with actual hydraulic loss values in the pumps. EPR values were higher in the multistage pump with the guide ring than the pump without a guide ring under part-load flow conditions (0.2Qd). However, the vortex flow in the pump was weakened (or eliminated) by the guide ring as flow rate increased; this reduced energy loss in the chambers. Flow passing the chamber was stabilized by the guide ring, which decreased shock and vortex loss in the chamber and guide vane. Under both designed flow condition and overload conditions, the EPR values of the guide ring-equipped multistage pump were lower than those without the guide ring. Furthermore, minimum efficiency index (MEI) values were also calculated for the two chamber structures; it was found that overall efficiency of pump with guide ring is better than that without.

scholarly journals Influence of Inlet Angle of Guide Vane on Hydraulic Performance of an Axial Flow Pump Based on CFD

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Lei Xu ◽  
Dongtao Ji ◽  
Wei Shi ◽  
Bo Xu ◽  
Weigang Lu ◽  
...  
Keyword(s):  
Working Conditions ◽  
Flow Rate ◽  
Guide Vane ◽  
Axial Flow ◽  
Hydraulic Performance ◽  
Hydraulic Loss ◽  
Rate Region ◽  
Axial Flow Pump ◽  
Inlet Angle ◽  
Flow Pump

Axial flow pump has been widely used in hydraulic engineering, agriculture engineering, water supply and sewerage works, and shipbuilding industry. In order to improve the hydraulic performance of pump under off-design working conditions, the influence of the inlet segment axial chord and inlet angle adjustment of the guide vane on the pump segment efficiency and flow filed was simulated by using the renormalization group (RNG) k − ε turbulent model based on the Reynolds-averaged Navier–Stokes equations. The results indicate that the inlet segment axial chord and inlet angle adjustment of guide vane have a strong influence on the pump segment efficiency. Considering the support function and hydraulic loss of the guide vane, the inlet segment axial chord is set to 0.25 times the axial chord of guide vane. On the basis of the inlet angle of the guide vane under design conditions, when the inlet segment angle is turned counterclockwise, the pump segment efficiency is improved in the lower flow rate region; moreover, the pump segment efficiency is improved in the larger flow rate region when the inlet segment angle is turned clockwise. As the conditions deviate from the design working conditions, the influence of the guide vane inlet angle on the pump segment efficiency increases. If the inlet segment angle is properly adjusted under off-design working conditions, the flow pattern in the guide vane is improved and the hydraulic loss is decreased, because the inlet segment angle matches with the flow direction of impeller outlet; consequently, the pump segment efficiency is increased.

Aerodynamic Improvement of a Transonic Fan Outlet Guide Vane Using 3D Design Optimization

2011 ◽  
Author(s):  
Giles Endicott ◽  
Toyotaka Sonoda ◽  
Markus Olhofer ◽  
Toshiyuki Arima
Keyword(s):  
Cfd Simulation ◽  
Experimental Testing ◽  
Guide Vane ◽  
Numerical Technique ◽  
Boundary Layer Separation ◽  
Operating Conditions ◽  
Free Form ◽  
Optimized Design ◽  
3D Design ◽  
Transonic Fan

In this paper we follow the process of rapid design improvement for the fan outlet guide vane for a turbofan powering a very light jet. The small size of such engines leads to a low Reynolds number, resulting in flow-fields prone to boundary layer separation, causing significant losses in efficiency. This paper studies experimental testing in a scale rig, and numerical simulation using CFD, leading to the comparison of the two datasets and hence assessment of the numerical technique. The mesh employed by the CFD simulation was modified using Free Form Deformation to create different geometric designs, and hence an optimization scheme was subsequently utilized to find the deformation of 28 variables which maximized aerodynamic performance. The final optimized design displayed a novel oscillatory casing profile, while the blade shape had increased camber relative to the baseline. The improvement in pressure loss was approximately 20% across the range of operating conditions studied.

Hydraulic Design of Inlet Guide Vane and its Full Flow Passage Numerical Simulation on Centrifugal Pump

2014 ◽  
Author(s):  
Hucan Hou ◽  
Yongxue Zhang ◽  
Zhenlin Li ◽  
Xin Zhou ◽  
Zizhe Wang
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Guide Vane ◽  
Hydraulic Performance ◽  
Design Flow ◽  
Inlet Guide Vane ◽  
Hydraulic Efficiency ◽  
Flow Passage ◽  
Setting Angle ◽  
Hydraulic Design

In order to effectively improve hydraulic performance of centrifugal pump on off-conditions, the hydraulic design of inlet guide vane (IGV) was completed by adopting two dimensional theory in-house code based on one kind of IS series of centrifugal pump, which can achieve pre-whirl regulation of centrifugal pump. During design process the trailing edge of vane is assumed as equal velocity moment condition, and the distribution of vane setting angle along meridional streamline is also given as a quartic function firstly, the camber line is then drawn by point-by-point integration method and thickened at both sides along circumferential direction. With local vortex dynamics diagnosis theory, the optimal improvement of vane space shape can be finished by adjusting the design parameters of vane setting angle distribution coefficient ap. The full flow passage numerical simulations of centrifugal pump with IGV device are completed to analyze the influence of pre-whirl regulation on hydraulic performance of centrifugal pump under various pre-whirl angles. The results show that the pre-whirl regulation can improve the hydraulic performance of centrifugal pump on off-conditions. Under the positive pre-whirl regulation conditions, the best efficient point shift to small flow rate zone, and under the negative pre-whirl regulation conditions it moves to large flow rate zone. Compared with the pump without IGV device at the same flow rate condition of 0.8Q (Q the design flow rate), the hydraulic efficiency of centrifugal pump with IGV device improves obviously and reaches up to 1.43%. Meanwhile compared with that installed with the straight vanes designed based on the traditional theory, the inner flow field of centrifugal pump with the designed vanes improves and the overall hydraulic efficiency of centrifugal pump is somewhat increased.

scholarly journals Experimental Issues in Testing a Semiactive Technique to Control Earthquake Induced Vibration

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Nicola Caterino ◽  
Mariacristina Spizzuoco ◽  
Julian M. Londoño ◽  
Antonio Occhiuzzi
Keyword(s):  
Large Scale ◽  
Experimental Testing ◽  
Practical Experience ◽  
Structural Testing ◽  
Frame Structure ◽  
Semiactive Control ◽  
Electrical Currents ◽  
Wide Range ◽  
And Control ◽  
Steel Frame Structure

This work focuses on the issues to deal with when approaching experimental testing of structures equipped with semiactive control (SA) systems. It starts from practical experience authors gained in a recent wide campaign on a large scale steel frame structure provided with a control system based on magnetorheological dampers. The latter are special devices able to achieve a wide range of physical behaviours using low-power electrical currents. Experimental activities involving the use of controllable devices require special attention in solving specific aspects that characterize each of the three phases of the SA control loop: acquisition, processing, and command. Most of them are uncommon to any other type of structural testing. This paper emphasizes the importance of the experimental assessment of SA systems and shows how many problematic issues likely to happen in real applications are also present when testing these systems experimentally. This paper highlights several problematic aspects and illustrates how they can be addressed in order to achieve a more realistic evaluation of the effectiveness of SA control solutions. Undesired and unavoidable effects like delays and control malfunction are also remarked. A discussion on the way to reduce their incidence is also offered.

The Effect of a Downstream Rotor on the Measured Performance of a Transonic Turbine Nozzle

1986 ◽  
Vol 108 (2) ◽  
pp. 269-274
Author(s):  
R. G. Williamson ◽  
S. H. Moustapha ◽  
J. P. Huot
Keyword(s):  
Performance Evaluation ◽  
Aspect Ratio ◽  
Flow Field ◽  
Large Scale ◽  
Outer Wall ◽  
Nozzle Flow ◽  
Turning Angle ◽  
Low Aspect Ratio ◽  
Transonic Turbine ◽  
Mach Numbers

Two nozzle designs, involving the same low aspect ratio, high turning angle vanes, and differing in outer wall contour, were tested over a range of exit Mach numbers up to supersonic values. The experiments were conducted on a large-scale, full annular configuration with and without a representative rotor downstream. Nozzle performance was found to be significantly affected by rotor operation, the influence depending on the detailed characteristics of the nozzle flow field, as well as on the design and operation of the rotor itself. It is suggested that performance evaluation of low aspect ratio nozzles of high turning angle may require appropriate testing with a rotor.

Abstract 3736: Applying the Carotid Atherosclerosis Score in a Clinical Environment: a Feasibility Study

Stroke ◽  
2012 ◽  
Vol 43 (suppl_1) ◽  
Author(s):  
Dongxiang Xu ◽  
Jie Sun ◽  
Yan Song ◽  
Daniel S Hippe ◽  
Min Chen ◽  
...  
Keyword(s):  
Neurological Symptom ◽  
Carotid Atherosclerosis ◽  
Treatment Options ◽  
Outer Wall ◽  
Classification Performance ◽  
Clinical Environment ◽  
Plaque Instability ◽  
Wall Area ◽  
Increasing Trend ◽  
Symptom Status

Background Carotid atherosclerosis is a leading cause of stoke. Recent studies have shown that its severity can be stratified by the Carotid Atherosclerosis Score (CAS) as measured by MRI. However, these studies were performed using customized imaging sequences, coils and comprehensive plaque analysis by specialized human reviewers, which are not generally available in a clinical environment. Whether CAS can be applied for clinical risk assessment is unknown. In this study, we used clinically collected MRI data to compute CAS. We investigated the correlation between CAS and the prevalence of neurological symptoms and disrupted luminal surface (DLS), an indicator of plaque instability, to evaluate the feasibility of translating CAS for clinical use. Methods Seventy six patients with either symptomatic or asymptomatic carotid disease detected by ultrasound were recruited. All patients underwent a multi-contrast MRI with clinical sequences and a commercially available coil. The lumen and outer wall boundaries and DLS were outlined manually and the plaque components were identified automatically using histologically validated image analysis software. The maximum wall thickness (MWT) and maximum % area (100 x area/[wall area]) of lipid-rich necrotic core (LRNC) were outputted by the software to compute CAS as follows: CAS=1 with MWT&lt2.0mm, CAS=2 with LRNC&lt20%, CAS=3 with LRNC between 20% and 40% and CAS=4 with LRNC&gt40%. Trend analysis was done to evaluate the associations between CAS and prevalence of symptoms and DLS. The area under the receiver operating characteristic (ROC) curve was used to evaluate the classification performance of CAS. Results Of the 76 patients, there was a significant increasing trend (p=0.01) between CAS scores and neurological symptom status. The presence of DLS also demonstrated a significant increasing trend (p&lt0.001) versus CAS with rates 0% (0/7), 7% (2/27), 35% (7/20) and 59% (13/22). ROC analysis of CAS also showed it was a good classifier of symptom status (AUC = 0.67, p=0.01) and DLS (AUC = 0.80, p&lt0.001) Conclusion In this study, we conclude that the CAS computed from clinically collected MRI data can stratify the severity of carotid atherosclerotic disease as indicated by neurological symptom status and DLS, both of which are important in monitoring patients and evaluating treatment options. Further study is needed to assess how a fully automated CAS analysis affects the quality of the score and how well the score can stratify the risk of future outcomes.

Large-scale three-dimensional anisotropic topology optimization of variable-axial lightweight composite structures

2021 ◽  
pp. 1-15
Author(s):  
Yuqing Zhou ◽  
Tsuyoshi Nomura ◽  
Enpei Zhao ◽  
Kazuhiro Saitou
Keyword(s):  
Topology Optimization ◽  
Composite Structures ◽  
Large Scale ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Optimization Method ◽  
Optimized Design ◽  
Adaptive Meshing ◽  
Design Synthesis ◽  
Fiber Placement

Abstract Variable-axial fiber-reinforced composites allow for local customization of fiber orientation and thicknesses. Despite their significant potential for performance improvement over the conventional multiaxial composites and metals, they pose challenges in design optimization due to the vastly increased design freedom in material orientations. This paper presents an anisotropic topology optimization method for designing large-scale, 3D variable-axial lightweight composite structures subject to multiple load cases. The computational challenges associated with large-scale 3D anisotropic topology optimization with extremely low volume fraction are addressed by a tensor-based representation of 3D orientation that would avoid the 2π periodicity of angular representations such as Euler angles, and an adaptive meshing scheme, which, in conjunction with PDE regularization of the density variables, refines the mesh where structural members appear and coarsens where there is void. The proposed method is applied to designing a heavy-duty drone frame subject to complex multi-loading conditions. Finally, the manufacturability gaps between the optimized design and the fabrication-ready design for Tailored Fiber Placement (TFP) is discussed, which motivates future work toward a fully-automated design synthesis.

scholarly journals Study of Mean- and Turbulent-Velocity Fields in a Large-Scale Turbine-Vane Passage

1980 ◽  
Vol 102 (1) ◽  
pp. 88-95 ◽  
Author(s):  
D. A. Bailey
Keyword(s):  
Boundary Layer ◽  
Laser Doppler Velocimetry ◽  
Large Scale ◽  
Guide Vane ◽  
Velocity Fields ◽  
Inlet Guide Vane ◽  
Test Conditions ◽  
Passage Vortex ◽  
Turbine Vane ◽  
The Mean

Laser-Doppler velocimetry was used to investigate the secondary flow in the endwall region of a large-scale turbine inlet-guide-vane passage. The mean and turbulent velocities were measured for three different test conditions. The different test conditions consisted of variations in the blade aspect ratio and the inlet boundary-layer thickness or all three cases, a passage vortex was identified and its development documented. The turbulent stresses within the vortex were found to be quite low in comparison with the turbulence in the inlet boundary layer.

Investigation of Wedge Probe Wall Proximity Effects: Part 2—Numerical and Analytical Modeling

1997 ◽  
Vol 119 (3) ◽  
pp. 605-611 ◽  
Author(s):  
P. D. Smout ◽  
P. C. Ivey
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Outer Wall ◽  
Aerodynamic Characteristics ◽  
Proximity Effects ◽  
Wake Flow ◽  
Scale Model ◽  
Flow Structures ◽  
Flow Features ◽  
Wall Proximity

An experimental study of wedge probe wall proximity effects is described in Part 1 of this paper. Actual size and large-scale model probes were tested to understand the mechanisms responsible for this effect, by which free-stream pressure near the outer wall of a turbomachine may be overindicated by up to 20 percent dynamic head. CFD calculations of the flow over two-dimensional wedge shapes and a three-dimensional wedge probe were made in support of the experiments, and are reported in this paper. Key flow structures in the probe wake were identified that control the pressures indicated by the probe in a given environment. It is shown that probe aerodynamic characteristics will change if the wake flow structures are modified, for example by traversing close to the wall, or by calibrating the probe in an open jet rather than in a closed section wind tunnel. A simple analytical model of the probe local flows was derived from the CFD results. It is shown by comparison with experiment that this model captures the dominant flow features.

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