Jin Chen

Study of CFD simulation of a 3-D wind turbine

A roof-top scaled experimental wind turbine was simulated in FLUENT. Meshing technique for wind turbine blades was studied and a suitable mesh was achieved. The SST k-ω model was set to be the turbulence model in FLUENT. Detailed settings were studied to maintain a convergent and more accurate simulation. The simulation predicted the wind turbine power coefficient in different tip speed ratios. The flow field around the blade, and pressure distributions were also analyzed. The simulation results were compared with its experimental data, showing an agreement. The comparison validated the simulation method, proving that with suitable meshing and setting for FLUENT, simulations could be accurate and reliable.

A General Profile Parameterization of Hydrodynamic Journal Bearings for Efficient Shape Optimization

A new approach for shape optimization of hydrodynamic journal bearings using a profile parameterization method has been evaluated. A mathematical model for optimization has been derived using the solution of the hydrodynamic lubrication equations. A Fourier series function was used to represent the general film geometry in the bearing. The objective was then to determine the Fourier coefficients that maximized the load capacity with constraint on the minimum film thickness. The mathematical model, based on the Reynolds equation, was solved using the PDE Toolbox in MATLAB. The optimization process was achieved using a genetic algorithm (GA) also available within MATLAB. The results showed that this new method for bearing shape optimization achieved significantly higher load capacities than in previous published studies.

Validation of the CQU-DTU-LN1 series of airfoils

The CQU-DTU-LN1 series of airfoils were designed with an objective of high lift and low noise emission. In the design process, the aerodynamic performance is obtained using XFOIL while noise emission is obtained with the BPM model. In this paper we present some validations of the designed CQU-DTU-LN118 airfoil by using wind tunnel measurements in the acoustic wind tunnel located at Virginia Tech and numerical computations with the inhouse Q3uic and EllipSys 2D/3D codes. To show the superiority of the new airfoils, comparisons with a NACA64618 airfoil are made. For the aerodynamic features, the designed Cl and Cl/Cd agrees well with the experiment and are in general higher than those of the NACA airfoil. For the acoustic features, the noise emission of the LN118 airfoil is compared with the acoustic measurements and that of the NACA airfoil. Comparisons show that the BPM model can predict correctly the noise changes.

Research on Design Methods and Aerodynamics Performance of CQU-DTU-B21 Airfoil

This paper presents the design methods of CQU-DTU-B21 airfoil for wind turbine. Compared with the traditional method of inverse design, the new method is described directly by a compound objective function to balance several conflicting requirements for design wind turbine airfoils, which based on design theory of airfoil profiles, blade element momentum (BEM) theory and airfoil Self-Noise prediction model. And then an optimization model with the target of maximum power performance on a 2D airfoil and low noise emission of design ranges for angle of attack has been developed for designing CQU-DTU-B21 airfoil. To validate the optimization results, the comparison of the aerodynamics performance by XFOIL and wind tunnels test respectively at Re=3×106 is made between the CQU-DTU-B21 and DU93-W-210 which is widely used in wind turbines.

Parametric and Controllable Shape Model of the Water-Lubricated Rubber Journal Bearing

This paper describes a general bearing profile for the water-lubricated rubber journal bearing. Characteristics of the most popular water-lubricated rubber journal bearing, the straight fluted bearing, were deeply analyzed. The bearing profile was expressed using subsection function and a parametric and controllable shape model was built. By adjusting the parameters of the shape model, the existing bearing profiles can be integrated into the shape model and some bran-new bearing profile can be generated from the model. The rigid film thickness equation was achieved using the shape model and the relationship between the load capacity and the parameters of the shape model was established with the neglecting of elastic deformation effect. It is seen that the dimensionless load capacity reduces with the increase of the transition arc radius, the flute radius and the number of flutes,. The Necessity of the research on the bearing profile and the correctness of the shape model are validated. The parametric and controllable shape model is the foundation to study the fluid-solid coupling effect and to carry out the multi-disciplinary cooperating optimization for the water-lubricated rubber journal bearing.

Design and FEA of 125T Face Shovel Excavator’s Arm

In manufacturing industry investors are always looking for economical and safe designs to cope up with the increasing demands of competitive markets. Keeping this objective in mind, arm of CE125 face shovel hydraulic excavator was re-designed to decrease manufacturing cost by reducing weight while keeping the stress approximately same as was used in the conventional design. For this purpose Pro/EngineerTM was used to generate Computer Aided Drawing (CAD) where cross section and inner structure of the design were kept to be semi-elliptical which helped to decrease the weight of the arm significantly. Initial stress analysis was also done in the same CAD software as it is quick and optimization can be done quickly. However sometimes it does not give accurate results because of poor meshing, so final analysis was done in AnsysTM. Analysis in AnsysTM calculated the stress to be 114 MPa while displacement came out to be 3.8 mm. Comparison of two models showed that the weight of new design is 5.1% less than the conventional one.

Experimental investigation of hydrodynamic journal bearing optimized shapes based on the general film thickness equation

In order to improve the performance of hydrodynamic journal bearings, the effect of bearing profiles had been investigated using a new approach for shape optimization of hydrodynamic journal bearings based on a profile parameterization method. The optimization process was carried out using Fourier series to describe the bearing profile. The load capacity increases with the increasing order of Fourier series. However the optimized result was almost fully achieved at the Fourier series of order 2. In this paper, three kinds of optimized shapes at the order of the general film thickness equation of 1, 2 and 3 were manufactured and taken as experimental objects respectively. Experimental apparatus was described and some experimental data was presented. The comparison was made for the optimized bearings between numeric values and experimental data. The results show that the new method for shape optimization of hydrodynamic journal bearings based on the general film thickness equation is feasible.