scholarly journals Optimization Study of Guide Vanes for the Intake Fan-Duct Connection Using CFD

Processes ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 1555
Author(s):  
Juan Pablo Hurtado ◽  
Bryan Villegas ◽  
Sebastián Pérez ◽  
Enrique Acuña
Keyword(s):  
Fluid Dynamics ◽  
Energy Savings ◽  
Guide Vane ◽  
Three Dimensional ◽  
Radius Of Curvature ◽  
Penetration Length ◽  
Curvature Ratio ◽  
Guide Vanes ◽  
Ventilation Shaft ◽  
Shock Loss

The connection between an intake fan and a ventilation shaft must be designed in such a way that it minimizes the energy waste due to singularity losses. As a result, the questions of which radius of curvature to use and if guide vanes have to be included need to be answered. In that case, the variables such as the number, upstream and downstream penetration length, radius of curvature, and width of the vanes, need to be defined. Although this work is oriented to mine ventilation, these questions are usually valid in other engineering applications as well. The objective of this study is to define the previously mentioned variables to determine the optimal design combination for the radius/diameter relationship (r/D). Computational fluid dynamics was used to determine the shock loss factor of seven elbow curvature ratios for a 3 m diameter duct and fan, with and without guide vanes to estimate the best performing configuration and, therefore, to maximize the fan airflow volume. The methodology used consisted of initially developing models in 2D geometries, to optimize the meshing and the CPU use, and studying separately the number of vanes, upstream and downstream penetration, radius of curvature, and width of the vanes for each curvature ratio (r/D). Then, the best-performing variable combinations for each curvature ratio were selected to be simulated and studied with the 3D geometries. The application of the guide vane designs for three-dimensional simulated geometries is presented, first without and then with guide vanes, including the shock loss factors obtained. The methodology and obtained results allowed quantifying the energy savings and to reduce the CFD simulations steps required to optimize the design of the elbow and guide vanes. The results obtained cannot be used with elbows in exhaust fans, because fluid dynamics phenomena are different.

Hydraulic Characteristics of the New Type Bulb Turbine With Micro-Head

2013 ◽  
Author(s):  
Lingyu Li ◽  
Yuan Zheng ◽  
Daqing Zhou ◽  
Zihao Mi
Keyword(s):  
Numerical Simulation ◽  
Cfd Simulation ◽  
Guide Vane ◽  
Three Dimensional ◽  
Flow Distribution ◽  
Three Dimensions ◽  
Guide Vanes ◽  
Runner Blade ◽  
Cfd Method ◽  
Bulb Turbine

The head of low-head hydropower stations is generally higher than 2.5m in the world, while micro-head hydropower resources which head is less than 2.5m are also very rich. In the paper, three-dimensional CFD method has been used to simulate flow passage of the micro-head bulb turbine. The design head and unit flow of the turbine was 1m and 3m3/s respectively. With the numerical simulation, the bulb turbine is researched by analyzing external characteristics of the bulb turbine, flow distribution before the runner, pressure distribution of the runner blade surface, and flow distribution of the outlet conduit under three different schemes. The turbine in second scheme was test by manufactured into a physical model. According to the results of numerical simulation and model test, bulb turbine with no guide vane in second scheme has simpler structure, lower cost, and better flow capacity than first scheme, which has traditional multi-guide vanes. Meanwhile, efficiency of second scheme has just little decrease. The results of three dimensions CFD simulation and test results agree well in second scheme, and higher efficiency is up to 77% which has a wider area with the head of 1m. The curved supports in third scheme are combined guide vanes to the fixed supports based on 2nd scheme. By the water circulations flowing along the curved supports which improve energy transformation ability of the runner, the efficiency of the turbine in third scheme is up to 82.6%. Third scheme, which has simpler structure and best performance, is appropriate for the development and utilization of micro-head hydropower resources in plains and oceans.

Blood Flow in Stented Arteries: A Parametric Comparison of Strut Design Patterns in Three Dimensions

2005 ◽  
Vol 127 (4) ◽  
pp. 637-647 ◽  
Author(s):  
Yong He ◽  
Nandini Duraiswamy ◽  
Andreas O. Frank ◽  
James E. Moore
Keyword(s):  
Fluid Dynamics ◽  
Flow Direction ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Three Dimensions ◽  
Low Flow ◽  
Radius Of Curvature ◽  
Shear Stresses ◽  
Stent Design ◽  
Flow Conditions

Background: Restenosis after stent implantation varies with stent design. Alterations in secondary flow patterns and wall shear stress (WSS) can modulate intimal hyperplasia via their effects on platelet and inflammatory cell transport toward the wall, as well as direct effects on the endothelium. Method of Approach: Detailed flow characteristics were compared by estimating the WSS in the near-strut region of realistic stent designs using three-dimensional computational fluid dynamics (CFD), under pulsatile high and low flow conditions. The stent geometry employed was characterized by three geometric parameters (axial strut pitch, strut amplitude, and radius of curvature), and by the presence or lack of the longitudinal connector. Results: Stagnation regions were localized around stent struts. The regions of low WSS are larger distal to the strut. Under low flow conditions, the percentage restoration of mean axial WSS between struts was lower than that for the high flow by 10–12%. The largest mean transverse shear stresses were 30–50% of the largest mean axial shear stresses. The percentage restoration in WSS in the models without the longitudinal connector was as much as 11% larger than with the connector. The mean axial WSS restoration between the struts was larger for the stent model with larger interstrut spacing. Conclusion: The results indicate that stent design is crucial in determining the fluid mechanical environment in an artery. The sensitivity of flow characteristics to strut configuration could be partially responsible for the dependence of restenosis on stent design. From a fluid dynamics point of view, interstrut spacing should be larger in order to restore the disturbed flow; struts should be oriented to the flow direction in order to reduce the area of flow recirculation. Longitudinal connectors should be used only as necessary, and should be parallel to the axis. These results could guide future stent designs toward reducing restenosis.

Minimisation of Ducted Flow Non-Uniformity Caused by Downstream Blockages

2016 ◽  
Author(s):  
M. E. Rife ◽  
F. Barbarossa ◽  
A. B. Parry ◽  
J. S. Green ◽  
L. di Mare
Keyword(s):  
Velocity Distribution ◽  
Guide Vane ◽  
Three Dimensional ◽  
Two Dimensions ◽  
Swirling Flows ◽  
Three Dimensions ◽  
Boundary Singularity ◽  
Blade Loading ◽  
Guide Vanes ◽  
Dimensional Boundary

Flow in annular ducts is sensitive to the presence of downstream blockages which can cause flow non-uniformities propagating far upstream of the blocking body. These effects can be exacerbated in swirling flows where a cascade of uniform guide vanes is present upstream of the blockage. This work uses two- and three-dimensional boundary singularity methods to model and optimise a guide vane cascade geometry to minimise the upstream velocity distortion. Starting from a uniform cascade, the geometry is modified to provide a uniform upstream velocity distribution and minimised blade-to-blade loading in two dimensions. The new geometry is then extrapolated to a three-dimensional annulus. A three-dimensional tool is used to further modify the geometry in three dimensions to minimise the velocity distortion in the whole annulus upstream of the cascade.

Flow Analysis of the Guide Vanes Region of Pump Turbine at the Slight Opening in the Pumping Startup Process

2016 ◽  
Author(s):  
Honggang Fan ◽  
Qingfeng Ji ◽  
Weili Liao ◽  
Haixia Yang
Keyword(s):  
Guide Vane ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Main Flow ◽  
Three Dimensional Model ◽  
Pump Turbine ◽  
Guide Vanes ◽  
Abrupt Changes ◽  
Dimensional Simulation ◽  
Pumped Storage

The unit of a Pumped Storage Power Station experienced abnormal noise and vibration in the guide vanes at the slight opening when the pump turbine was in the process of startup in the pumping mode. Based on this phenomena, the three dimensional model of the pump turbine was established, RNG k-epsilon two equations turbulence model was selected for the flow numerical simulation in the pump turbine because this model can simulate both the flow separation and vortex dynamics, and it is more accurate in the near wall areas. The governing equations were discretized with the finite volume method. The computation was carried out with three steps, 1.steady calculation, 2.unsteady calculation with constant guide vane opening, 3.unsteady calculations with the increase of the opening of guide vanes, by using the results of the last step as the initial condition. According to the three dimensional simulation results, the main flow between the guide vanes was deflected from attaching to the one vane to the other vane with the opening of the guide vanes. The calculation of complete 3D flow indicated that the deflections of the flows between the different adjacent guide vanes were basically the same, however, the deflections starting times had a few differences. The variation of the torque on the guide vane was also investigated, and the results shown the abrupt changes occurred during the deflection process of the main flow. When the torque produced by the servomotor cannot adapt quickly enough to the abrupt changes, the vibration and loud scrape noise might occur.

Effects of Guide-Vane Number in a Three-Dimensional 60-Deg Curved Side-Dump Combustor Inlet

2000 ◽  
Vol 123 (2) ◽  
pp. 211-218 ◽  
Author(s):  
Tong-Miin Liou ◽  
Hsin-Li Lee ◽  
Chin-Chun Liao
Keyword(s):  
Reynolds Number ◽  
Flow Separation ◽  
Laser Doppler Velocimetry ◽  
Guide Vane ◽  
Rectangular Cross Section ◽  
Three Dimensional ◽  
Mean Velocity ◽  
Guide Vanes ◽  
Aspect Ratios ◽  
The One

Three-dimensional flowfields in a 60-deg curved combustor inlet duct of rectangular cross-section with and without guide vanes were measured using Laser-Doppler velocimetry for the longitudinal, radial, and spanwise velocity components. The Reynolds number based on the bulk mean velocity and hydraulic diameter was 2.53×104. The main parameters examined were the guide-vane number and Reynolds number. The results show that to completely eliminate flow separation in the curved combustor inlet three guide vanes should be installed. The critical Reynolds number for the absence of the flow separation is found to decrease with increasing product of radius and aspect ratios. In addition, it is found that in most regions the maximum radial mean velocity, difference between radial and spanwise normal stress, and the turbulent kinetic energy decrease with increasing guide-vane number. A rationale for the absence of flow separation in the one-vane case predicted by previous researchers is also provided.

Experimental and Numerical Investigations of Flowpath Profiling on Secondary Flow Losses in a Turbine Control Stage

2013 ◽  
Author(s):  
Nils Moser ◽  
Peter Steinhoff ◽  
Franz Joos
Keyword(s):  
Pressure Distribution ◽  
Secondary Flow ◽  
Guide Vane ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Formation Mechanisms ◽  
Guide Vanes ◽  
Numerical Investigations ◽  
Control Stage ◽  
Wide Range

The numerically and experimentally investigated industrial steam turbine control stage is derived from a real design. Due to the production process and costs of the guide vanes for control stages of steam turbines the flowpath profiling is rotationally symmetric. However the combination of the two-dimensional shroud contour and the flow deflection in the guide vane results in a fully three-dimensional end wall contour having a strong influence on the secondary flow features in the turbine control stage. To obtain an improved profile for the nozzle shroud the reduction of the total pressure loss over the guide vanes is taken as an optimization criterion. The three-dimensional contour generates a diffuser flowpath between the suction and the pressure side of two guide vanes perpendicular to the main flow direction. This diffuser geometry affects the pressure distribution over the guide vane and therefore the formation mechanisms of secondary flows. For the experimental and numerical investigations a baseline shroud design and two additional profiled contours are analyzed in detail. The control stage test rig is operated with air and is capable to represent a wide range of operating conditions. The measurements show a considerable increase of the stage efficiency and power output. The effect of the flowpath profiling on the pressure distribution over the guide vane is clearly proved.

Experimental and numerical analysis of the unsteady influence of the inlet guide vanes on cavitation performance of an axial pump

2018 ◽  
Vol 233 (11) ◽  
pp. 3816-3826 ◽  
Author(s):  
Zhiwei Guo ◽  
Jingye Pan ◽  
Zhongdong Qian ◽  
Bin Ji
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Guide Vane ◽  
Inlet Guide Vane ◽  
Guide Vanes ◽  
Inlet Guide Vanes ◽  
Cavitation Performance ◽  
Axial Pump ◽  
Simulation Results

The effect of the inlet guide vanes on cavitation performance of an axial pump is investigated to assess the mechanism for cavitation in pumps and improve their cavitation performance. The effect of inlet guide vane angles on cavitation performance was assessed experimentally, and computational fluid dynamics was used to analyze the inner flow field of the axial pump and to probe the cavitation mechanism. The simulation results agree qualitatively with the experimental data, showing that cavitation performance is improved with positive inlet guide vane angles but hampered with negative ones. The cavitation performance itself is controlled by the cavitation volume, which first expands circumferentially when the net positive suction head decreases from a certain large value and then develops toward the axis radially after the net positive suction head reaches a certain value. This is when the cavitation performance deteriorates. Comparing cavitation volume for the critical net positive suction head as determined by two different methods, the method based on efficiency drop (NPSHeff.,1%) is found to be more suitable than that based on head drop (NPSHhead.,3%). Furthermore, the distribution of swirl is shown to be closely related to the distribution of cavitation, a feature that may be used to predict cavitation along the impeller.

Guide Vanes Inference on Hydraulic Characteristics of Tubular Pump

2011 ◽  
Author(s):  
Jin Yan ◽  
Liu Chao ◽  
Takaharu Tanaka
Keyword(s):  
Guide Vane ◽  
Three Dimensional ◽  
Flow Fields ◽  
System Efficiency ◽  
Hydraulic Characteristics ◽  
Pump Impeller ◽  
Guide Vanes ◽  
Hydraulic Losses ◽  
Pumping System ◽  
Cfd Method

The blade number of pump guide vane is an important factor that affects hydraulic characteristics of the pumping system, since the diffusion angle after the impeller is larger than as usual. It is necessary to pay more attention for its calculation and analysis. By CFD method the numeric simulation was conducted to a bulb tubular pump with different guide vane blades and the three dimensional flow fields within whole passage of pumping system was obtained. There are five different number of guide vane blades (4 blades, 5 blades, 7 blades, 8 blades and improved 5 blades) selected for the simulation and performance prediction. The influences of the guide vanes numbers on the system performance are analyzed. The hydraulic losses increases with the increase of the number of guide vane blades while the efficiency of pumping system is not fully comply with this relationship. The system efficiency for which 5 guide vanes were adopted is higher than others with different number of guide vane blades; also the velocity and the pressure distribution of flow fields are more uniform. The system efficiency for which 5 improved guide vanes is the highest with lowest hydraulic losses. The recommended alternative of guide vane is presented for the pump impeller.

scholarly journals Load Rejection Transient Process Simulation of a Kaplan Turbine Model by Co-Adjusting Guide Vanes and Runner Blades

Energies ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 3354 ◽  
Author(s):  
Huixiang Chen ◽  
Daqing Zhou ◽  
Yuan Zheng ◽  
Shengwen Jiang ◽  
An Yu ◽  
...  
Keyword(s):  
Transient Process ◽  
Guide Vane ◽  
Three Dimensional ◽  
Flow Simulation ◽  
Decisive Role ◽  
Axial Thrust ◽  
Guide Vanes ◽  
Kaplan Turbine ◽  
Flow Configurations ◽  
Cfd Method

To obtain the flow mechanism of the transient characteristics of a Kaplan turbine, a three-dimensional (3-D) unsteady, incompressible flow simulation during load rejection was conducted using a computational fluid dynamics (CFD) method in this paper. The dynamic mesh and re-meshing methods were performed to simulate the closing process of the guide vanes and runner blades. The evolution of inner flow patterns and varying regularities of some parameters, such as the runner rotation speed, unit flow rate, unit torque, axial force, and static pressure of the monitored points were revealed, and the results were consistent with the experimental data. During the load rejection process, the guide vane closing behavior played a decisive role in changing the external characteristics and inner flow configurations. In this paper, the runner blades underwent a linear needle closure law and guide vanes operated according to a stage-closing law of “first fast, then slow,” where the inflection point was t = 2.3 s. At the segment point of the guide vane closing curve, a water hammer occurs between guide vanes and a large quantity of vortices emerged in the runner and the draft tube. The pressure at the measurement points changes dramatically and the axial thrust rises sharply, marking a unique time in the transient process. Thus, the quality of a transient process could be effectively improved by properly setting the location of segmented point. This study conducted a dynamic simulation of co-adjustment of the guide vanes and the blades, and the results could be used in fault diagnosis of transient operations at hydropower plants.

Improvements in Performance Characteristics of Single-Stage and Multistage Centrifugal Compressors by Simultaneous Adjustments of Inlet Guide Vanes and Diffuser Vanes

1987 ◽  
Vol 109 (1) ◽  
pp. 41-47 ◽  
Author(s):  
H. Simon ◽  
T. Wallmann ◽  
T. Mo¨nk
Keyword(s):  
Performance Characteristic ◽  
Guide Vane ◽  
Three Dimensional ◽  
Maximum Efficiency ◽  
Inlet Guide Vane ◽  
Centrifugal Compressors ◽  
Guide Vanes ◽  
Inlet Guide Vanes ◽  
The Individual ◽  
Simultaneous Adjustment

Nowadays, multistage geared centrifugal compressors are most often equipped with three-dimensional impellers and adjustable inlet guide vane cascades, at least upstream of the first stage. Optimum stage efficiencies are made possible by optimum axial in-flow into each stage and freely selectable pinion shaft speeds. Combined with intercooling of the medium, the result is high machine efficiency with good operating ranges. Additional increases in efficiency can be achieved by means of vaned diffusers. Due to the attendant restriction to the working range, this solution is not common in production compressors. Nevertheless, the working range can be distinctly expanded by adjusting the diffuser vanes. In addition, the combination of simultaneous adjustment to inlet guide vanes and diffuser vanes enables an increase in machine efficiency over the entire operating range as compared with regulation using only inlet guide vanes or diffuser vanes. This paper reports on the development of centrifugal compressor stages equipped with vaned diffusers. The impellers have backward-curved blades. Experimental determination of suitable schedules for simultaneous adjustment of both inlet guide vanes and diffuser vanes, depending on the desired performance characteristic, will be dealt with in detail. Furthermore, some examples of the overall performance maps for multistage inter-cooled geared compressors will be shown as a result of combining the performance characteristic curves of the individual stages. The operating ranges and regions of maximum efficiency are optimally matched to the requirements in question by means of suitable adjustment schedules.

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