scholarly journals The Effect of Load Control on the Performance of Contra-Rotating Fans

Processes ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 1227
Author(s):  
Xi Zhang ◽  
Xingyu Jia ◽  
Xuan Jiang
Keyword(s):  
Load Distribution ◽  
Design Method ◽  
Pressure Rise ◽  
Axial Distance ◽  
Element Analysis ◽  
Load Matching ◽  
Key Factor ◽  
Flow Mechanisms ◽  
Flow Field Characteristics ◽  
The Relationship

In recent years, few studies focused on adjusting the load distribution of contra-rotating fan (CRF) blades. To improve the overall performance of CRFs, we used a design code to build 32 sets of CRFs to determine the effects of three factors—the front and rear rotor load matching, the load distribution of each rotor and the axial distance between the rotors—on the total pressure rise and efficiency of CRFs using numerical calculations. The relationship between the CRF blades load and velocity components was theoretically analyzed using blade element analysis and the forward problem method. According to the performance curve, it can be concluded that the rear rotor (RR) is the key factor that determines the performance of CRFs. Through analyzing Mach number contours from different perspectives, the relationship between velocity and adjustment load was verified. Furthermore, the flow field characteristics for three specific CRFs were explored at the stall points, design points and choke points to reveal their flow mechanisms. This study provides a reference for the CRF blade design method.

Design method of a novel variable speed ratio line gear mechanism

2020 ◽  
pp. 095440622093772
Author(s):  
Yangzhi Chen ◽  
Xiaoping Xiao ◽  
Daoping Zhang ◽  
Haifei Xiao ◽  
Yueling Lyu
Keyword(s):  
Design Method ◽  
Speed Ratio ◽  
Variable Speed ◽  
Element Analysis ◽  
Constraint Equations ◽  
Order Curve ◽  
Contact Curve ◽  
Gear Mechanism ◽  
Parallel Axis ◽  
The Relationship

Based on the space curve meshing theory, a novel noncircular line gear mechanism was advanced, namely, this paper presented a design method of the variable speed ratio noncircular line gear with coplanar axes. Firstly, the universal contact curve equations of the constant speed ratio and variable speed ratio line teeth were established. After the constraint equations of the rotating angle of the driving and driven variable speed ratio noncircular line gears were analyzed and established, the relationship between the rotating angle of the driven variable speed ratio noncircular line gear and the parameter t in the VSR area was assumed to be a piecewise fourth-order curve. Then, the contact curve equations of the variable speed ratio noncircular line gears were derived, and the entity models of variable speed ratio noncircular line gears were built. The prototypes of the parallel axis and intersecting axis variable speed ratio noncircular line gears were manufactured by Stereo Lithography Apparatus, and the speed ratios were measured on the kinematic test rig. The kinematic and finite element analysis results demonstrate that the relationship between the rotating angle of the driven variable speed ratio noncircular line gear and the parameter t conforms to the designed function and the noncircular line teeth smoothly achieve the preset VSR transmission. The proposed design method is helpful to design the variable speed ratio noncircular line gears with lower theoretical sliding rate and wider variation range of the speed ratio; consequently, the designed variable speed ratio noncircular line gears have better applicability in specific variable speed ratio applications.

scholarly journals Optimization of isolated and combined pad foundation using computer aided application of finite element approach

2021 ◽  
Vol 6 (3) ◽  
pp. 24-41
Author(s):  
Ubi Stanley E.
Keyword(s):  
Finite Element ◽  
Design Method ◽  
Bending Moment ◽  
Basic Structure ◽  
Ease Of Use ◽  
Foundation Design ◽  
Element Analysis ◽  
Mesh Selection ◽  
Element Approach ◽  
The Relationship

Most Finite Element packages provide means to generate meshes automatically. However, the user is usually confronted with the problem of not knowing whether the mesh generated is appropriate for the problem at hand. Since the accuracy of the Finite Element results is mesh dependent, mesh selection forms a very important step in the analysis of isolated and combined footing pad foundation. SAFE is an ultimate tools use in the design of concrete floors and foundation system, hence provide a suitable means for the user. From framing layout all the way through to detail drawing production, SAFE integrate every aspect of engineering design which are in one process easy and intuitive environment. SAFE provides unmatched benefits to the engineer with its truly unique combination of power, comprehensive capabilities, and ease-of-use. In the context of this research, we have plotted graphs showing the relationship between the nodes and displacement with the stress patterns as generated from the software. It is understood from the graph that multiple elements in the process of meshing will make the footing to be at equilibrium. The research also carry the shape deformed diagram which shows the deformation of the footing due to the impose load (stress) on the footing, it also give the bending moment diagram of the footings. The basic structure and analysis of the single and double pad footing foundations have been designed using Finite Element Analysis (FEA) with the failure planes being considered. The results obtained, it is assumed that FEA is an ideal design method that breaks foundation design into basic elements and nodes that shows the action of the loading on the footings.

scholarly journals On the design of a novel fully compliant spherical four-bar mechanism

2019 ◽  
Vol 11 (9) ◽  
pp. 168781401987954
Author(s):  
Volkan Parlaktaş ◽  
Engin Tanık ◽  
Çağıl Merve Tanık
Keyword(s):  
Compliant Mechanism ◽  
Design Method ◽  
Optimization Method ◽  
Maximum Output ◽  
Element Analysis ◽  
Free Position ◽  
Flexural Hinges ◽  
Arc Lengths ◽  
The Relationship ◽  
Novel Design

In this article, a novel fully compliant spherical four-bar mechanism is introduced and its generalized design methodology is proposed. The original fully compliant mechanism lies on a plane at the free position (undeflected position); therefore, it has the advantages of ease of manufacturing, minimized parts, and no backlash. First, the mobility conditions of the mechanism are obtained. The dimensions of the mechanism are optimally calculated for maximum output rotation, while keeping the deflection of flexural hinges at an acceptable range. Using an optimization method, design tables are prepared to display the relationship between arc lengths and corresponding deflections of flexural hinges. Input–output torque relationship and stresses at compliant segments are obtained analytically. A mechanism dimensioned by this novel design method is analyzed by a finite element analysis method, and the analytical results are verified. Finally, the mechanism is manufactured and it is ensured that the deflections of the compliant segments are consistent with the theoretical results.

Analysis of Crown Control Characteristics for SmartCrown Work Roll

2010 ◽  
Vol 156-157 ◽  
pp. 1261-1265 ◽  
Author(s):  
Hong Bo Li ◽  
Jie Zhang ◽  
Jian Guo Cao ◽  
Li Li Meng
Keyword(s):  
Design Method ◽  
Work Roll ◽  
Strip Width ◽  
Key Factor ◽  
The Relationship ◽  
Work Rolls

SmartCrown work roll contour has been brought in China for several years, but the research of crown control characteristics of SmartCrown work roll is lacking, especially the relationship and difference between SmartCrown and CVC work rolls. The paper researched the principle and design method of SmartCrown work roll contour first, and then the relation and difference between the SmartCrown and CVC work roll contours were pointed out, the crown control ability of different strip width was discussed too. From the analysis and research, it can be concluded that the contour angle of SmartCrown work roll contour is the most key factor for its crown control characteristics.

Theoretical Calculation and Simulation Experiment of Tooth Contact in Planetary Gearing with Small Tooth Number Difference

2015 ◽  
Vol 778 ◽  
pp. 212-217
Author(s):  
Fei Li ◽  
Jian Fang Xia
Keyword(s):  
Theoretical Calculation ◽  
Load Distribution ◽  
Simulation Experiment ◽  
Calculation Formula ◽  
Element Analysis ◽  
Tooth Contact ◽  
Small Tooth ◽  
Tooth Number ◽  
The Relationship ◽  
Meshing Process

This article focuses on multi-tooth contact existing in planetary gearing with small tooth number difference. On the basis of analyses of the meshing process of planetary gearing with small tooth number difference, it puts forward the calculation formula of contacting tooth pairs to the theoretical clearance angles and establishes the theoretical mathematical model for calculating the number of contacting tooth in the meshing process of planetary gearing. The model is used to calculate the data of certain particular planetary gearing mechanism and sort out the relationship between contacting tooth and the load distribution of tooth pairs. And the simulation experiment has been made using the ABAQUS finite element analysis software to verify the validity of the theoretical calculation formula.

scholarly journals Experimental Study of the Instationary Flow Between Two Ducted Counter-Rotating Rotors

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
H. Nouri ◽  
A. Danlos ◽  
F. Ravelet ◽  
F. Bakir ◽  
C. Sarraf
Keyword(s):  
Design Method ◽  
Radial Profile ◽  
Tangential Velocity ◽  
Pressure Rise ◽  
Axial Distance ◽  
Flow Angle ◽  
Rotation Rates ◽  
Wall Pressure Fluctuations ◽  
Wide Range ◽  
High Efficient

The purpose of this work is to study experimentally the aerodynamic characteristics of a subsonic counter-rotating axial-flow fans system operating in a ducted configuration. The fans of diameter D=375 mm were designed to match the specification point using an original iterative method: the front rotor blade cascade is designed with a conventional inverse method, setting the radial distribution of the Euler work. The through-flow is then computed using an axisymmetric and radial equilibrium assumption, with empirical models of losses. The rear rotor is not conventional but is designed to straighten the radial profile of the tangential velocity. The design of the front rotor is then modified until the stage meets the requirements. The experimental setup is arranged such that the rotation rate of each fan is independently controlled and that the axial distance between the rotors can be varied from 17% to 310% of the midspan chord length. Systematic measurements of the global performances and local measurements of the velocity field and of the wall pressure fluctuations are performed, in order to first validate the design method, and to explore the effects of the two specific free parameters of the system, the axial spacing and the ratio of rotation rates. The results show that the efficiency is strongly increased compared to a conventional rotor or to a rotor-stator stage. The developed design method slightly overpredicts the pressure rise and slightly underpredicts the best ratio of rotation rates. Flow angle measurements downstream of the stage show that the outflow is not completely straightened at the design point. Finally, the system is highly efficient on a wide range of flow rates and pressure rises: this system has thus a very flexible use, with a large patch of high efficient operating points in the parameter space.

scholarly journals Application of the Thin Slice Model for Determination of Face Load Distribution along the Line of Contact and the Relative Load Distribution Measured along Gear Root

2020 ◽  
Vol 66 (5) ◽  
pp. 300-310
Author(s):  
Wiktor Kamycki ◽  
Stanisław Noga
Keyword(s):  
Stress Distribution ◽  
Load Distribution ◽  
Computer Software ◽  
Test Rig ◽  
Element Analysis ◽  
Thin Slice ◽  
Fea Simulation ◽  
Load Intensity ◽  
Tooth Flank ◽  
The Relationship

This article concerns the investigation of the relationship between stress distribution caused by contact during tooth flank engagement and tensile stress distribution due to bending at the tooth root. Four different approaches are discussed. The first refers to ISO 6336 guidelines describing the relationship with a simple empirical formula. The second is the proposed thin slice model developed in MATLAB computer software. The third approach is based on finite element analysis (FEA). The last experimental method uses a bespoke test rig designed and manufactured for this work. The thin slice model has been verified against ISO 6336 guidelines, FEA simulation, and the test rig measurements. Two phenomena have been observed: coupling and edge effect, both of which impact the relationship between load intensity distribution for contact and bending.

A Design Method of Position Schemes for Particle Dampers Applied to a Flywheel

2013 ◽  
Vol 482 ◽  
pp. 163-168
Author(s):  
Bin Liu ◽  
Yan Rong Wang ◽  
Huan Huan Feng
Keyword(s):  
Design Method ◽  
Radial Position ◽  
Damping Capacity ◽  
Acceleration Response ◽  
Element Analysis ◽  
Acceleration Amplitude ◽  
Specific Parameter ◽  
Particle Damping ◽  
Particle Dampers ◽  
The Relationship

The design method research of position schemes for particle dampers applied to a flywheel under sinusoidal excitation has been investigated, in which discrete element method (DEM) and finite element analysis are used to study the relationship between the damping capacity of dampers filled with different metal particles and the dimensionless acceleration amplitude, and the specific parameter of radial position is introduced to discuss the influence on particle damping caused by different dampers attachment locations. A series of corresponding experimental investigation are conducted subsequently and the results indicate an auxiliary position scheme if the acceleration response of optimum location exceeds the threshold. It can be concluded that with the help of the specific parameter of radial position, the experiment results can be well explained, in addition, the design efficiency and accuracy will be raised, especially in the condition that the particles mass is strictly limited.

Analysis of magnetic force and dynamic characteristic for non-contact permanent magnet linear drive device

2020 ◽  
Vol 64 (1-4) ◽  
pp. 1337-1345
Author(s):  
Chuan Zhao ◽  
Feng Sun ◽  
Junjie Jin ◽  
Mingwei Bo ◽  
Fangchao Xu ◽  
...  
Keyword(s):  
Finite Element ◽  
Permanent Magnet ◽  
Dynamic Characteristic ◽  
Driving Force ◽  
Magnetic Circuit ◽  
Response Speed ◽  
Computation Method ◽  
Element Analysis ◽  
Element Simulation ◽  
The Relationship

This paper proposes a computation method using the equivalent magnetic circuit to analyze the driving force for the non-contact permanent magnet linear drive system. In this device, the magnetic driving force is related to the rotation angle of driving wheels. The relationship is verified by finite element analysis and measuring experiments. The result of finite element simulation is in good agreement with the model established by the equivalent magnetic circuit. Then experiments of displacement control are carried out to test the dynamic characteristic of this system. The controller of the system adopts the combination control of displacement and angle. The results indicate that the system has good performance in steady-state error and response speed, while the maximum overshoot needs to be reduced.

Studies on Downstream Stator With Rotor Re-Staggering and Forward Sweeping in a Subsonic Axial Compressor Stage

2011 ◽  
Author(s):  
P. V. Ramakrishna ◽  
M. Govardhan
Keyword(s):  
Flow Field ◽  
Computational Model ◽  
Flow Rate ◽  
Total Pressure ◽  
Axial Compressor ◽  
Pressure Rise ◽  
Axial Distance ◽  
Compressor Stage ◽  
Numerical Work ◽  
Stagger Angle

The present numerical work studies the flow field in subsonic axial compressor stator passages for: (a) preceding rotor sweep (b) preceding rotor re-staggering (three stagger angle changes: 0°, +3° and +5°); and (c) stator sweeping (two 20° forward sweep schemes). The following are the motives for the study: at the off-design conditions, compressor rotors are re-staggered to alleviate the stage mismatching by adjusting the rows to the operating flow incidence. Fundamental to this is the understanding of the effects of rotor re-staggering on the downstream component. Secondly, sweeping the rotor stages alters the axial distance between the successive rotor-stator stages and necessitates that the stator vanes must also be swept. To the best of the author’s knowledge, stator sweeping to suit such scenarios has not been reported. The computational model for the study utilizes well resolved hexahedral grids. A commercial CFD package ANSYS® CFX 11.0 was used with standard k-ω turbulence model for the simulations. CFD results were well validated with experiments. The following observations were made: (1) When the rotor passage is closed by re-staggering, with the same mass flow rate and the same stator passage area, stators were subjected to negative incidences. (2) Effect of stator sweeping on the upstream rotor flow field is insignificant. Comparison of total pressure rise carried by the downstream stators suggests that an appropriate redesign of stator is essential to match with the swept rotors. (3) While sweeping the stator is not recommended, axial sweeping is preferable over true sweeping when it is necessary.

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