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The aeroelastic modeling of Tjaereborg wind turbine blades was performed based on the unsteady Reynolds Averaged Navier-Stokes equations (URANS) combined with Finite Element Method (FEM) in a loosely coupled manner. This method was verified by comparing numerical and experiment results at four axial inflow wind speeds. Furthermore, the aeroelastic performance of Tjaereborg wind turbine under yaw angle of 10°, 30° and 60°were computed and analyzed. The results showed that the average power and thrust of the wind turbine decreased with increasing yaw angle, along with the increasing oscillation amplitude under large yaw angle. The aerodynamic load showed periodic change within one revolution of rotor, resulting in the blade deflection and the strain present considerably asymmetric distributions. The maximum deflection and strain occurred at azimuth angle of about90° and their minimum values occurred at azimuth angle of about 270°. Besides, both the maximum deflection and strain under yaw conditions became larger than those in axial inflow condition do. For Tjaereborg wind turbine, the coupled solver gave a higher average power and thrust than the CFD solver alone. The aerodynamic performances showed more asymmetrical characters under the combined effect of yaw and fluid structure interaction (FSI).

The Nd7.69Fe92.31-xTix (x = 0, 4, 8, 12) alloy were prepared by arc smelting and high energy ball milling method. The morphology and phase structure of the powders were analyzed by Scanning Electron Microscope (SEM), X-ray diffraction (XRD) and the effect of the Ti content on microwave absorbing properties of the powders were measured by a vector network analyzer (VNA). The results reveal that the samples mainly consisted of Nd2Fe17 and α-Fe crystal structure. The minimum absorption peak frequency shifts to lower frequency region firstly and then shifts to higher frequency region with the increasing amount of Ti content. The minimum reflection loss of Nd7.69Fe84.31Ti8 powder is-31.35 dB and the bandwidth of R < -5 dB reach 3.6 GHz when the coating thickness is 2.0 mm. With the increasing of the coating thickness, the minimum reflectivity peak value of the Nd7.69Fe84.31Ti8 moves to lower frequency region and the minimum reflection loss increase firstly and then decrease. And the minimum reflection value of Nd7.69Fe84.31Ti8 alloy can reach to-38.74 dB (microwave absorption rate 99.99%) at 5.68 GHz, and the bandwidth of R < -10 dB reach 1.12 GHz with the best matching thickness of 2.2 mm.

The wake of a wind turbine has substantial influence on the aerodynamic performance of downstream wind turbine. Unsteady numerical simulations are performed in this paper to investigate the wake structure of a three-bladed H-type VAWT (vertical axis wind turbine) and the influence on the aerodynamic performance of downstream wind turbine. A simplified two-dimensional model is used considering the blades are straight. Unsteady Reynolds Averaged Navier–Stokes equations are solved using FlowVision software, which uses dynamic grid method to handle the blade rotation. The SST turbulence model is used for turbulence modeling. The distance between two wind turbines is from 5D to 17D with 2D intervals, where D denotes the wind turbine diameter. The wind speed is 5.07 m/s, corresponding to a tip speed ratio of 2.15. The power coefficients of two wind turbines are compared in detail. The discussions focus on the periodic variations of the aerodynamic performance and flow variables of two turbines with two typical distances, i.e., 7D and 15D, respectively. The simulation results show that the velocity recovery distance needed for a VAWT is usually larger than 15D.

This paper mainly focuses on the modeling and simulation of the doubly fed induction generator (DFIG) based wind turbine generation system. In this paper, a new method which combines the mechanical part and electrical part is presented to model the wind turbine generation system. The turbine rotor blade is modeled by the lifting line model and the aerodynamic forces are solved by the improved free vortex wakes method with the supplementary of two dimensional aerodynamic data (three dimensional corrected). The control system of pitching and generator with voltage oriented control (VOC) are established in Matlab/Simulink. The drive train is also modeled with two mass model. In order to realize the coupling computation of the wind turbine model, a data link is built to transfer the parameters between aerodynamic part and electrical part. In this way, the interaction between turbine rotor and generator could be predicted. The validations are firstly made to ensure the reliability of the model. Then the performance of a 1.5 MW wind turbine is investigated with this integrated model under different wind and symmetrical grid voltage dip condition.

In order to accurately analysis the aerodynamic characteristic variations of wind turbines under shear, the influence of axial and shear on the aerodynamic characteristic of a horizontal-axis wind turbine is simulated in this paper by using a sliding grid method based on FlowVision. By using the TJÆREBORG wind turbine as the object of study, a three-dimensional model of a uniform wind flow can be created. The CFD calculation results, the experimental results and the Bladed results can be used to confirm the reliability of the model. In order to investigate the effect of wind shear with regard to three-dimensional unsteady flow characteristics and a three-dimensional flow field in a wind turbine impeller, an analysis of wheel wind speed of 11m/s and an investigation of the influence of wind shear on turbine performance are carried out.

According to the characteristics of cage wind turbines’ dynamic characteristics which change following the wind speed changes, the dynamic mathematical models of cage wind turbines major subsystems have been established, including the aerodynamic subsystem model, drive train subsystem model and generator subsystem model. Then these nonlinear dynamic models with time-varying parameters have been integrated and linearized to obtain the whole linear time-varying parameters dynamic mathematical model. To take the 2MW cage wind turbines wind turbine as example, the proposed model is validated by the study on the dynamic characteristics of cage wind turbines with wind speed variation , and the results show that the proposed model could provide a theoretical support for optimal control of the cage wind turbines.

In this paper, non-deterministic CFD (computational fluid dynamics) simulations have been performed to investigate the uncertain effects of stochastic boundary conditions on the aerodynamic performance of wind turbines. A NIPRC (non-intrusive probabilistic collocation) method is employed, which is coupled with a commercial flow solver. A 2D (two-dimensional) airfoil case is used to validate the non-deterministic simulation, where the angle of attack is considered as an uncertain parameter in a Gaussian distribution. The simulation results are compared with Monte Carlo simulation results. Based on the validation, non-deterministic CFD simulations were performed on a 3D (three-dimensional) wind turbine blades case, where the wind speed is considered as an uncertain parameter. The discussions mainly focus on the total performance variations and the uncertainty propagation in the fluid field. The simulation results show that the input uncertainty of the inlet velocity results in a high variation zone in the pressure distribution near the blade root, and which decreases from the root to the tip. With the wind speed increases, flow separation is observed. The separation vortex regions correspond to the maximum variation area, and the maximum variation extends to the trailing edge even to the whole suction side.

The aerodynamic performance and the bypass flow field of a vertical axis wind turbine under self-starting are investigated using CFD simulations in this paper. The influence of pitch angle variations on the performance of the wind turbine during self-starting is presented. A two-dimensional model of the wind turbine with three blades is employed. A commercial software FlowVision is employed in this paper, which uses dynamic Cartesian grid. The SST turbulence model is used for turbulence modeling, which assumes the flow full turbulent. Based on the comparison between the computed time-dependent variations of the rotation speed with the experimental data, the time-dependent variations of the torque are presented. The characteristics of self-starting of the wind turbine are analyzed with the pitch angle of 0o、-2oand 2o. The influence of pitch angle variations on two-dimensional unsteady viscous flow field through velocity contours is discussed in detail.

The aerodynamic performance of a compressor is highly sensitive to uncertain working conditions. This paper presents an efficient robust aerodynamic optimization method based on non-deterministic computational fluid dynamic (CFD) simulation and Multi-Objective Genetic Algorithm (MOGA). A NonIntrusive Polynomial Chaos method is used in conjunction with an existing well-verified CFD module to quantify the uncertainty propagation in the flow field. This method is validated by comparing with a Monte Carlo (MC) method through full three dimensional CFD simulations on an axial compressor (NASA rotor 37). Based on the validation, the non-deterministic CFD is coupled with a surrogate-based MOGA to search for the Pareto front. A practical engineering application is implemented to the robust aerodynamic optimization of rotor 37 under random outlet static pressure. Two curve angles and two sweep angles at tip and hub are used as design variables. Convergence analysis shows that the surrogate-based MOGA can obtain the Pareto front properly. Significant improvements of both mean and variance of the efficiency are achieved by the robust optimization. The comparison of the robust optimization results with that of the initial design and a deterministic optimization demonstrate that the proposed method can be applied to turbomachinery successfully. Copyright c © 2011 John Wiley & Sons, Ltd.

In order to assess the influences of curved hole passage on cooling effectiveness and flow structure of turbine blade leading edge, the detached eddy simulation is applied to numerically investigate the AGTB turbine cascade under the condition of global blowing ratio M=0.7. The straight or curved cooling holes are located at either the pressure or suction side near the leading edge. The analysis and discussion focus on the local turbulence structure; influence of pressure gradient on the structure, and distribution of cooling effectiveness on the blade surface. The numerical results show that cooling hole with curved passage could bring positive impact on the increase of the local cooling effectiveness. On the suction side, the increased cooling effectiveness could be about 82% and about 77% on the pressure side, compared to the conventional straight hole.

The buildings of domestic wear the upper floors and an underground in-depth reconciliation tendency to do and the possibility of fire occurrence at the time of formation accident is coming to be high. Therefore will be scattered to various place and is established and prevention of disaster information of the receiver which will integrate there is a necessity which will manage. In this paper away where each receiver is installed in the fire for the remote monitoring and controld able to connect to the Internet and fiber optic cable that can be networked fire receiver and control desk was constructed. Between each device can be used by the fire, and more depending on the status of monitoring and alarm, control and maintenance can be performed to develop an integrated management system. The system is evaluated by the criteria of the KFI, and for each segment of the signal propagation time to perform experiments confirmed the reliability of the performance.

The NdFe magnetic absorbing materials were prepared by rapid solidification and high-energy ball milling method. The effect of high-energy ball milling on particle morphology, organizational structure and microwave absorbing properties of NdFe magnetic absorbing materials were analyzed with the aid of X-ray diffractometer, scanning electron microscope and vector network analysis. The results show that the Nd2Fe17 and α-Fe phase are refined, the particles become smaller and thinner; the span-ratio of the particles increases along with time during the process of high-energy ball milling; and meanwhile, the frequency of absorbing peak reduces. The absorbing bandwidth broadens as the increase of the time of ball milling, except that of 48h.The minimum reflectance of the powder decreases from -22dB to - 44dB under the circumstances that the time of high energy ball milling reaches 48h and the thickness of the microwave absorbing coating is 1.5mm. But it rebounds to about - 6dB when the time of ball milling reaches 72h.

Wind turbine aerodynamic-mistuning phenomenon during the operation may cause great harm. This article is based on sliding mesh technique of three dimensional Unsteady CFD method,taking NREL Phase VI wind turbine as an example,study the pneumatic performance of wind turbine under the axial-flow condition ,and compare with the experimental data.After validate the accuracy of the method,according to the effect of yaw and wind shear on the wind turbine aerodynamicmistuning ,researched have been conducted: In a wind shear condition,the aerodynamic performance after the blade rotating one circle have been calculated in the different wind profile index.Because of the shear wind velocity, Airfoil load and flow parameters fluctuate approximately like the patterm of cyclical cosine function with the change of azimuth.And with wind profiles index and spanwise position increases, impulse amplitudes have been also increased;Under the circumstances of the constant wind speed and variable yaw angle , The aerodynamic power decreases with the increase of the yaw angle There are also some big differences at different azimuth angle of blade section. Keywords-yaw;aerodynamic;mistuning;shear;wind turbine

Electro-optical tracking devices in the television or infrared automatic tracking system, miss distance lag system overshoot increased, lengthened the transitional period, affecting the stability control system and reduce the tracking precision.Feedforward control technology is to improve the tracking accuracy and to maintain the stability of the system an effective way. The speed of introduction of the forecast information as feedforward control signals constitute the equivalent composite control can be approximated to achieve feedforward control technology. The filter for the synthesis of the target location information with lag, interference is the key problem of compound control technology. In order to obtain the high-precision forecasting velocity of moving target, Kalman filter with the measurement lag is designed. Forecasting velocity of moving target can obtain by forecasting the synthesis target position with measurement lag. The actual Electro-optical tracking equivalent compound control system simulation and experimental results show that the velocity of moving target can be forecasted by using the methods and tracking precision can be improved in servo-control system.

Flow structures in a turbine cascade with film cooling injections at the blade leading edge are investigated numerically for three cooling models of slots, straight cylindrical and spanwise inclined cylindrical holes under various blowing ratios, 0, 0.5, 0.7, 1.1, and 1.5. The numerical simulations are well compared with experiment results of static pressure and oil film visualization of blade surfaces. Discussions are mainly focused on the 3D flow structures within a blade passage. The results show that the 3D flow and energy loss production is greatly affected by the cooling injections, especially near the blade pressure surface.Copyright © 2008 by ASME

In order to get more insight into the influence of blade lean angle on the flow performance in the design process of a one-stage turbine with large diameter/height ratio, a through-flow tool of AxSTREAM is used to make the investigation. Based on the optimization of design, stage performances of variable working conditions for twenty-one lean angles in stator and in rotor respectively are simulated through DoE analysis. Some results for five typical lean angles are compared with the data of a 3D CFD simulation performed with FINE/TURBO software. The changes of reaction and static pressure distributions under different lean angles are presented, with discussion and analysis of the influence of parameters, such as diameter/height ratio and rotation speed, on the best lean angle.

This paper presents the CFD simulations of a high speed centrifugal compressor impeller using the NUMECA Fine/Turbo software with the one equation turbulence model of Spalart-Allmaras. The simulations are validated via comparison with the experimental data. The computational grid densities are changed with the impeller tip size and a grid independent study is carried out. The flow physics of the compressor impeller is numerically studied in details, in particular, the formation of shocks and their effects on the 3D flow and the secondary flow structure are analyzed at different operation conditions, with comparison to low speed machines. It is found that the energy loss production is greatly affected by the shock waves and their interaction with the boundary layers in the inducer portion, while in the other portion, the secondary flow structure is globally the same as those in low speed machines.Copyright © 2005 by ASME