Actuator Disks(AD)can provide characterizations of rotor wakes while reducing computational expense associated with modeling the fully resolved blades.This work presents an unsteady actuator disk method based on surfa...Actuator Disks(AD)can provide characterizations of rotor wakes while reducing computational expense associated with modeling the fully resolved blades.This work presents an unsteady actuator disk method based on surface circulation distribution combined with empirical data,blade element theory and rotor momentum theory.The nonuniform circulation distribution accounts for 3 D blade load effects,and in particular,tip loses.Numerical simulations were conducted for the isolated pressure sensitive paint model rotor blade in hover and forward flight using the HMB3 CFD solver of Glasgow University.Validation of CFD results in comparison with published numerical data was performed in hover,for a range of blade pitch angles using fully turbulent flow and the k-x SST model.In forward flight,the vortex structures predicted using the unsteady actuator disk model showed configurations similar to the ones obtained using fully resolved rotor blades.Despite the reduced grid cells number,the CFD results for AD models captured well the main vortical structures around the rotor disk in comparison to the fully resolved cases.展开更多
There is a growing interest in propellers for transport aircraft as well as regional airliners from the viewpoint of energy saving. An important consideration for utilizing a propeller propulsion system on aircraft is...There is a growing interest in propellers for transport aircraft as well as regional airliners from the viewpoint of energy saving. An important consideration for utilizing a propeller propulsion system on aircraft is the aerodynamic interaction between the propeller slipstream and other aerodynamic surfaces. It is therefore necessary to use a simplified but relatively accurate tool for propeller modeling, with the widely used actuator disk model. The advantage of this model is that it is easy to use and inex- pensive in terms of computation time required. In addition, it also produces acceptable results. In this study, a new regionalized actuator disk model was utilized in the analysis of propeller slipstream interference effects on a real four-propeller aircraft. The results are compared with the cases of inactive actuator disks, which shows that the propeller slipstream causes an increase in the lift and drag coefficients. An evident yawing effect caused by the rotating slipstream was noticed, which should be taken into account in the design phase. The regionalized actuator disk model is evaluated as a fast and relatively accurate model for propeller preliminary design.展开更多
A simulation model is presented for the creep process of the rotating disks under the radial pressure in the presence of body forces. The finite strain theory is applied. The material is described by the Norton-Bailey...A simulation model is presented for the creep process of the rotating disks under the radial pressure in the presence of body forces. The finite strain theory is applied. The material is described by the Norton-Bailey law generalized for true stresses and logarithmic strains. A mathematical model is formulated in the form of a set of four partial differential equations with respect to the radial coordinate and time. Necessary initial and boundary conditions are also given. To make the model complete, a numerical procedure is proposed. The given example shows the effectiveness of this procedure. The results show that the classical finite element method cannot be used here because both the geometry and the loading （body forces） change with the time in the creep process, and the finite elements need to be redefined at each time step.展开更多
The actuator disc method is an engineering approach to reduce computer resources in computational fluid dynamics(CFD)simulations of helicopter rotors or aeroplane propellers.Implementation of an actuator disc based on...The actuator disc method is an engineering approach to reduce computer resources in computational fluid dynamics(CFD)simulations of helicopter rotors or aeroplane propellers.Implementation of an actuator disc based on rotor circulation distribution allows for approximations to be made while reproducing the blade tip vortices.Radial circulation distributions can be formulated according to the nonuniform Heyson-Katzoff“typical load”in hover.In forward flight,the nonuniform disk models include“azimuthal”sin and cos terms to reproduce the blade cyclic motion.The azimuthal circulation distribution for a forward flight mode corresponds to trimmed conditions for the disk rolling and pitching moments.The amplitude of the cos harmonic is analysed and compared here with presented in references data and CFD simulations results.展开更多
The present paper contributes to the modeling of unsteady flow analysis of vertical axis wind turbine (VAWT). Double multiple streamtube (DSMT) model was applied for the performance prediction of straight bladed fixed...The present paper contributes to the modeling of unsteady flow analysis of vertical axis wind turbine (VAWT). Double multiple streamtube (DSMT) model was applied for the performance prediction of straight bladed fixed pitch VAWT using NACA0018 airfoil at low wind speed. A moving mesh technique was used to investigate two-dimensional unsteady flow around the same VAWT model with NACA0018 airfoil modified to be flexible at 150 from the main blade axis of the turbine at the trailing edge located about 70 % of the blade chord length using fluent solving Reynolds average Navier-strokes equation. The results obtained from DMST model and the simulation results were then compared. The result shows that the CFD simulation with airfoil modified has shown better performance at low tip speed ratios for the modeled turbine.展开更多
Fused deposition modelling(FDM), a widely used rapid prototyping process, is a promising technique in manufacturing engineering. In this work, a method for characterizing elastic constants of FDM-fabricated materials ...Fused deposition modelling(FDM), a widely used rapid prototyping process, is a promising technique in manufacturing engineering. In this work, a method for characterizing elastic constants of FDM-fabricated materials is proposed. First of all, according to the manufacturing process of FDM, orthotropic constitutive model is used to describe the mechanical behavior. Then the virtual fields method(VFM) is applied to characterize all the mechanical parameters(Q, Q, Q, Q) using the full-field strain,which is measured by digital image correlation(DIC). Since the principal axis of the FDM-fabricated structure is sometimes unknown due to the complexity of the manufacturing process, a disk in diametrical compression is used as the load configuration so that the loading angle can be changed conveniently. To verify the feasibility of the proposed method, finite element method(FEM) simulation is conducted to obtain the strain field of the disk. The simulation results show that higher accuracy can be achieved when the loading angle is close to 30?. Finally, a disk fabricated by FDM was used for the experiment. By rotating the disk, several tests with different loading angles were conducted. To determine the position of the principal axis in each test, two groups of parameters(Q, Q, Q, Q) are calculated by two different groups of virtual fields. Then the corresponding loading angle can be determined by minimizing the deviation between two groups of the parameters. After that, the four constants(Q, Q, Q, Q) were determined from the test with an angle of 27?.展开更多
Applying the rule of laminar flow in the gap between two parallel disks, thetheoretical model of a new type MR damper is established, the damping characteristic and structuralcharacteristic of the MR damper are analyz...Applying the rule of laminar flow in the gap between two parallel disks, thetheoretical model of a new type MR damper is established, the damping characteristic and structuralcharacteristic of the MR damper are analyzed. Experimental results show that the model can reflectthe fundamental characteristics of the disk-gap MR damper.展开更多
A physical model of molten slag granulation by rotary disk was developed based on the mechanism of New-tonian liquid granulation. For geometrical similarity, the radius ratio of model disk to the prototype disk was ch...A physical model of molten slag granulation by rotary disk was developed based on the mechanism of New-tonian liquid granulation. For geometrical similarity, the radius ratio of model disk to the prototype disk was chosen as 1 ： 1. For dynamic similarity, equality of Ohnesorge number between the model and the prototype was achieved firstly by compounding rosin and paraffin wax with mass ratio of 4 ~ 1 as simulation liquid of molten blast furnace （BF） slag, and the simulation material can satisfy the similarity of liquid solid transformation during falling in the medium; then equality of Reynolds number and Weber number was obtained by controlling the volumetric flow rate and the rotary speed, respectively. Model accuracy was verified by comparing the simulation data with the results re ported in literature, which showed good agreement with the calculation results of empirical equation and the actual molten BF slag granulation from the view point of particle size. Furthermore, influences of disk radius, rotary speed and liquid flow rate on granulation were discussed using the developed model, and the Kitamura equation was modi-fied according to the simulation data which can predict particle size more accurately. Using the modified equation, the operation parameters were predicted according to the flow rate of molten industrial BF slag.展开更多
This paper studies the flow structural interaction (FSI) within a hard disk drive (HDD) through the use of a novel coupling method. The interaction studied was the fluid induced vibration in the HDD. A two step coupli...This paper studies the flow structural interaction (FSI) within a hard disk drive (HDD) through the use of a novel coupling method. The interaction studied was the fluid induced vibration in the HDD. A two step coupling approach was used, where the fluid and structural components were solved sequentially. The result obtained was a ratio of 0.65 between the vibration amplitudes of a fixed head stack assembly (HSA) and a moving HSA. The ratio was next applied on a real 3.5 inch HDD, to allow the parameter to be further improved upon. A new benchmark index of 0.69 was developed from this. This parameter may allow future researchers to model the out of plane vibrations of a HSA easily, saving precious time. A 31% more accurate simulation of FSI within 3.5 inch HDD at 15000 rpm is achieved by the use of this new coupling method and benchmark index.展开更多
Current exertion is made to depict and search out the flow features imparted to viscid fluid flow over a rotational disk. Impression of magnetic field with rotating fluid is generated by interacting it in radial direc...Current exertion is made to depict and search out the flow features imparted to viscid fluid flow over a rotational disk. Impression of magnetic field with rotating fluid is generated by interacting it in radial direction.Nano structured particles with magnetized fluid are also incorporated in the upshot of chemical reaction and absorptive/generative heat induction. Von Kumaran procedure is executed to obtain flow narrating differential expressions.Flow pattern regarding thermal, momentum profiles are comprehended with the support of shooting method and RungeKutta methods. Furthermore, to get more realistic view of result description computational algorithm is modified by improving Runge-Kutta coefficients with Cash and Carp method. The aspects of flow controlling parameters like momentum slip parameter, magnetic strength parameter, Brownian motion parameter, thermophoresis parameter are adorned in sketches. Findings of these architects are accumulated in conclusion section.展开更多
基金co-supported by the grant‘‘State task of the Education and Science Ministry of Russian Federation”agreement(No.075-03-2020-051/3 from 09.06.2020,theme No.fzsu-2020-0021)。
文摘Actuator Disks(AD)can provide characterizations of rotor wakes while reducing computational expense associated with modeling the fully resolved blades.This work presents an unsteady actuator disk method based on surface circulation distribution combined with empirical data,blade element theory and rotor momentum theory.The nonuniform circulation distribution accounts for 3 D blade load effects,and in particular,tip loses.Numerical simulations were conducted for the isolated pressure sensitive paint model rotor blade in hover and forward flight using the HMB3 CFD solver of Glasgow University.Validation of CFD results in comparison with published numerical data was performed in hover,for a range of blade pitch angles using fully turbulent flow and the k-x SST model.In forward flight,the vortex structures predicted using the unsteady actuator disk model showed configurations similar to the ones obtained using fully resolved rotor blades.Despite the reduced grid cells number,the CFD results for AD models captured well the main vortical structures around the rotor disk in comparison to the fully resolved cases.
基金supported by the Key Projects in the National Science&Technology Pillar Program during the Eleventh Five-Year Plan Period(Grant No.2009BAG12A01)
文摘There is a growing interest in propellers for transport aircraft as well as regional airliners from the viewpoint of energy saving. An important consideration for utilizing a propeller propulsion system on aircraft is the aerodynamic interaction between the propeller slipstream and other aerodynamic surfaces. It is therefore necessary to use a simplified but relatively accurate tool for propeller modeling, with the widely used actuator disk model. The advantage of this model is that it is easy to use and inex- pensive in terms of computation time required. In addition, it also produces acceptable results. In this study, a new regionalized actuator disk model was utilized in the analysis of propeller slipstream interference effects on a real four-propeller aircraft. The results are compared with the cases of inactive actuator disks, which shows that the propeller slipstream causes an increase in the lift and drag coefficients. An evident yawing effect caused by the rotating slipstream was noticed, which should be taken into account in the design phase. The regionalized actuator disk model is evaluated as a fast and relatively accurate model for propeller preliminary design.
文摘A simulation model is presented for the creep process of the rotating disks under the radial pressure in the presence of body forces. The finite strain theory is applied. The material is described by the Norton-Bailey law generalized for true stresses and logarithmic strains. A mathematical model is formulated in the form of a set of four partial differential equations with respect to the radial coordinate and time. Necessary initial and boundary conditions are also given. To make the model complete, a numerical procedure is proposed. The given example shows the effectiveness of this procedure. The results show that the classical finite element method cannot be used here because both the geometry and the loading （body forces） change with the time in the creep process, and the finite elements need to be redefined at each time step.
基金Work of Russian coauthors was supported by the grant"FZSU-2020-0021"(No.075-03-2020-051/3 from 09.06.2020)of the Min-istry of Education and Science of the Russian Federation.
文摘The actuator disc method is an engineering approach to reduce computer resources in computational fluid dynamics(CFD)simulations of helicopter rotors or aeroplane propellers.Implementation of an actuator disc based on rotor circulation distribution allows for approximations to be made while reproducing the blade tip vortices.Radial circulation distributions can be formulated according to the nonuniform Heyson-Katzoff“typical load”in hover.In forward flight,the nonuniform disk models include“azimuthal”sin and cos terms to reproduce the blade cyclic motion.The azimuthal circulation distribution for a forward flight mode corresponds to trimmed conditions for the disk rolling and pitching moments.The amplitude of the cos harmonic is analysed and compared here with presented in references data and CFD simulations results.
文摘The present paper contributes to the modeling of unsteady flow analysis of vertical axis wind turbine (VAWT). Double multiple streamtube (DSMT) model was applied for the performance prediction of straight bladed fixed pitch VAWT using NACA0018 airfoil at low wind speed. A moving mesh technique was used to investigate two-dimensional unsteady flow around the same VAWT model with NACA0018 airfoil modified to be flexible at 150 from the main blade axis of the turbine at the trailing edge located about 70 % of the blade chord length using fluent solving Reynolds average Navier-strokes equation. The results obtained from DMST model and the simulation results were then compared. The result shows that the CFD simulation with airfoil modified has shown better performance at low tip speed ratios for the modeled turbine.
基金the financial support from the National Natural Science Foundation of China (Grants 11672153, 11232008, and 11227801)
文摘Fused deposition modelling(FDM), a widely used rapid prototyping process, is a promising technique in manufacturing engineering. In this work, a method for characterizing elastic constants of FDM-fabricated materials is proposed. First of all, according to the manufacturing process of FDM, orthotropic constitutive model is used to describe the mechanical behavior. Then the virtual fields method(VFM) is applied to characterize all the mechanical parameters(Q, Q, Q, Q) using the full-field strain,which is measured by digital image correlation(DIC). Since the principal axis of the FDM-fabricated structure is sometimes unknown due to the complexity of the manufacturing process, a disk in diametrical compression is used as the load configuration so that the loading angle can be changed conveniently. To verify the feasibility of the proposed method, finite element method(FEM) simulation is conducted to obtain the strain field of the disk. The simulation results show that higher accuracy can be achieved when the loading angle is close to 30?. Finally, a disk fabricated by FDM was used for the experiment. By rotating the disk, several tests with different loading angles were conducted. To determine the position of the principal axis in each test, two groups of parameters(Q, Q, Q, Q) are calculated by two different groups of virtual fields. Then the corresponding loading angle can be determined by minimizing the deviation between two groups of the parameters. After that, the four constants(Q, Q, Q, Q) were determined from the test with an angle of 27?.
基金This project is supported by National Natural Science Foundation of China (No.50135030).
文摘Applying the rule of laminar flow in the gap between two parallel disks, thetheoretical model of a new type MR damper is established, the damping characteristic and structuralcharacteristic of the MR damper are analyzed. Experimental results show that the model can reflectthe fundamental characteristics of the disk-gap MR damper.
基金Sponsored by China Postdoctoral Science Foundation(20110491517)Fundamental Research Funds for Central Universities of China(N100402012)Doctor Start-Up Fund of Natural Science Foundation of Liaoning Province of China(201120004)
文摘A physical model of molten slag granulation by rotary disk was developed based on the mechanism of New-tonian liquid granulation. For geometrical similarity, the radius ratio of model disk to the prototype disk was chosen as 1 ： 1. For dynamic similarity, equality of Ohnesorge number between the model and the prototype was achieved firstly by compounding rosin and paraffin wax with mass ratio of 4 ~ 1 as simulation liquid of molten blast furnace （BF） slag, and the simulation material can satisfy the similarity of liquid solid transformation during falling in the medium; then equality of Reynolds number and Weber number was obtained by controlling the volumetric flow rate and the rotary speed, respectively. Model accuracy was verified by comparing the simulation data with the results re ported in literature, which showed good agreement with the calculation results of empirical equation and the actual molten BF slag granulation from the view point of particle size. Furthermore, influences of disk radius, rotary speed and liquid flow rate on granulation were discussed using the developed model, and the Kitamura equation was modi-fied according to the simulation data which can predict particle size more accurately. Using the modified equation, the operation parameters were predicted according to the flow rate of molten industrial BF slag.
文摘This paper studies the flow structural interaction (FSI) within a hard disk drive (HDD) through the use of a novel coupling method. The interaction studied was the fluid induced vibration in the HDD. A two step coupling approach was used, where the fluid and structural components were solved sequentially. The result obtained was a ratio of 0.65 between the vibration amplitudes of a fixed head stack assembly (HSA) and a moving HSA. The ratio was next applied on a real 3.5 inch HDD, to allow the parameter to be further improved upon. A new benchmark index of 0.69 was developed from this. This parameter may allow future researchers to model the out of plane vibrations of a HSA easily, saving precious time. A 31% more accurate simulation of FSI within 3.5 inch HDD at 15000 rpm is achieved by the use of this new coupling method and benchmark index.
文摘Current exertion is made to depict and search out the flow features imparted to viscid fluid flow over a rotational disk. Impression of magnetic field with rotating fluid is generated by interacting it in radial direction.Nano structured particles with magnetized fluid are also incorporated in the upshot of chemical reaction and absorptive/generative heat induction. Von Kumaran procedure is executed to obtain flow narrating differential expressions.Flow pattern regarding thermal, momentum profiles are comprehended with the support of shooting method and RungeKutta methods. Furthermore, to get more realistic view of result description computational algorithm is modified by improving Runge-Kutta coefficients with Cash and Carp method. The aspects of flow controlling parameters like momentum slip parameter, magnetic strength parameter, Brownian motion parameter, thermophoresis parameter are adorned in sketches. Findings of these architects are accumulated in conclusion section.
