叶片共振频率测试仪的原理与使用

通过介绍研制的共振频率测试仪的测量原理、使用与校验方法 ,对不同状况下的测量数据进行了详细的分析 ,结果表明 ,测试仪经过标准信号发生器校验后 ,测量数据的重复性和稳定性较好 ,延时时间在 80～ 1 2 0ms的时间段最适宜测量频率 ,叶片的共振频率与其完整性有关 ,还与其裂纹及晶体结构有关 。

基于MC56F8037的水泵可调叶片压力测试装置研究

针对轴流泵可调节叶片综合受力情况,研究开发了基于DSP MC56F8037芯片的水泵叶轮调节机构下的压力测试系统。系统通过DSP MC56F8037在轴流泵运行情况下叶轮角度变化过程中对油压装置的油缸实时压力数据连续采集,同步处理后实时传输给上位机系统实现存储、打印、曲线显示等功能,并且将实测数据与理论模型计算数据进行了比对,取得了相一致的结果。

对风力发电机测试技术的研究分析

风能是可再生能源的一种,在风力发电过程中风力发电机发挥着关键性作用。为提高风力发电机运行可靠性、高效性,实现降本增效。本文结合6.45MW风力发电机组测试概况,详细论述叶片、风速、振动的测试方法,总结叶片振动情况及相关影响因素。风力发电机组叶片振动情况和风速、机组转速以及功率均存在一定连续。基于研究结果可以为风力发电机组的优化控制提供可靠依据。

一种玻璃纤维/环氧树脂复合材料测试叶片制备

文章总结了一种以9201A/B型环氧树脂制备风机叶片的制备过程,介绍了原材料的选择及依据,总结了叶片制备的完整工序,并对其进行性能测试和结果分析。

海上风电叶片结构设计中的前沿问题与挑战

为了有效提高风能开发的成本效益,海上风电正不断向“大型化”“深水化”发展,这给海上风电叶片材料和结构设计、载荷仿真和试验测试等环节带来了全新的技术挑战。文章通过探讨海上风电叶片结构设计在数值仿真和试验研究方面的现状与不足之处,以期为现有方法的改进提供新的见解、为深远海漂浮式风力机百米级大型叶片的合理设计和灾变防控提供参考。

基于MeanShift与Hough算法的风电叶片复合疲劳试验振动监测研究

为了解决风电叶片双轴疲劳加载中叶片振动状态的检测的实际工程问题,设计了基于单目视觉的精准跟踪方案。通过在视频中选定包含特征标志圆的具有一定特征的ROI区域,设计了基于Mean Shift的图形跟踪算法跟踪视频的R O I区域。并在R O I区域中,应用HO UGH算法,对标志圆进行识别,并识别计算圆心位置。通过这样的算法设计,有效避免了跟踪算法在精确定位应用的不足以及HOUGH算法的误识别问题。在基于模拟视频的实验中,算法计算的特征位置与实际位置之间完全一致,并且满足实时性要求。

Research on the cutting force of a pick

Cutting tests were done using a test bed designed to measure pick cutting forces when cutting coal and rock.The test equipment has a drum with two starting helical vanes.Cutting forces on a pick were measured as a function of coal compressive strength,pick carbide tip diameter and the cutting depth per drum revolution.The results show that the cutting force is linearly related to the compressive strength.The relationship between the cutting force and both the carbide tip diameter and the cutting depth are exponential.Fluctuation in the cutting force does not increase with coal compressive strength but it has a linear relationship to tip diameter.A plot of cutting force fluctuations versus the cutting depth follows a sigmoidal curve.Based on the analysis of these test results a theoretical basis is supplied for design and effective use of shearer drums.

Experimental investigation on fatigue of blade specimen subjected to resonance and effect of a damping hard coating treatment

Failures due to high-cycle fatigue have led to a high cost in aerospace engineering over the past few decades.In this paper,the experimental results of the fatigue behavior of compressor blade specimen subjected to resonance and the effects of a damping hard coating on relieving the fatigue progress are presented.The crack initiation and propagation processes were observed under resonance of the first bending mode by using the resonant frequencies as the indicator.Significant nonlinear features were observed in the spectrum of the blade with a fatigue crack.The finite element model considering the breathing crack was established with nonlinear contact based on the crack localization and size,which was obtained by ultrasonic phased array technology.The simulation results of the vibration behavior of the cracked blade were obtained and consistent with the experimental results.A NiCrAlY coating was deposited on the blade,and increases in the fatigue life were observed under the same condition.The results of this paper can help to better understand the fatigue of a compressor blade subjected to resonance and provide a preference for the application of a damping hard coating on compressor blades.

Influence of a Deflector or a Wall on Savonius Rotor Efficiency

The Savonius rotor is a vertical axis-wind machine composed of two half cylindrical blades presenting a central gap. It is a slow velocity machine compared with horizontal wind machines. Its efficiency is about twenty per cent. In this work experimental tests are presented using two kind of deflectors placed in front of the resistive blade. Such disposition allows to hide the resistant blade and to guide the flow toward the motrice blade. Two deflectors have been used： a short one and a long one. The results obtained in wind tunnel have shown that the long deflector is the more efficient, essentially for high values of the tip speed ratio. One has been interested, using a numerical approach, in the study of the influence of a wall on the aerodynamical field near the rotor.

Numerical and Experimental Study on Aerodynamic Performance of Small Axial Flow Fan with Splitter Blades

To improve the aerodynamic performance of small axial flow fan, in this paper the design of a small axial flow fan with splitter blades is studied. The RNG k-e turbulence model and SIMPLE algorithm were applied to the steady simulation calculation of the flow field, and its result was used as the initial field of the large eddy simulation to calculate the unsteady pressure field. The FW-H noise model was adopted to predict aerodynamic noise in the six monitoring points. Fast Fourier transform algorithm was applied to process the pressure signal. Experiment of noise testing was done to further investigate the aerodynamic noise of fans. And then the results obtained from the numerical simulation and experiment were described and analyzed. The results show that the static characteristics of small axial fan with splitter blades are similar with the prototype fan, and the static characteristics are improved within a certain range of flux. The power spectral density at the six monitoring points of small axial flow fan with splitter blades have decreased to some extent. The experimental results show sound pressure level of new fan has reduced in most frequency bands by comparing with prototype fan. The research results will provide a proof for parameter optimization and noise prediction of small axial flow fans with high performance.

Experimental study of the effect of blade tip clearance and blade angle error on the performance of mixed-flow pump

The hydraulic performance test of the mixed-flow pump has been carried out through selecting different blade tip clearances and various blade angle errors.The ratio of the mixed-flow pump efficiency reduction and the blade tip clearance variation(η/δ) varies with the flow rate coefficient revealing a parabolic trend.An empirical equation has been developed for the mixed-flow pump model by parabolic fitting.For the same blade tip clearance variation δ,the mixed-flow pump efficiency reduction η increases rapidly as the flow rate rises.For any given flow rate,the efficiency,the head and the shaft power of the mixed-flow pump all decrease with the increase of the blade tip clearance.Among them,the efficiency reduction η varies approximately linearly with the blade tip clearance variation δ.When the angle of an individual blade of the mixed-flow pump has a deviation,the performance curves will move and change.These curves have consistent change directions with the performance curves under the condition of all the blades rotated at the same time,but have smaller offset and lower range of variation.When an individual blade angle error changes to ±2°,the optimal efficiency of the mixed-flow pump will have no significant difference.When the individual blade angle error increases to ±4°,the optimal efficiency will decrease by 1%.

Unsteady Internal Flow Conditions of Mini-Centrifugal Pump with Splitter Blades

Mini centrifugal pumps having a diameter smaller than lOOmm are employed in many fields. But the design method for the mini centrifugal pump is not established because the internal flow condition for these small-sized fluid machines is not clarified and conventional theory is not suitable for small-sized pumps. Therefore, mini cen- trifugal pumps with simple structure were investigated by this research. Splitter blades were adopted in this re- search to improve the performance and the internal flow condition of mini centrifugal pump which had large blade outlet angle. The original impeller without the splitter blades and the impeller with the splitter blades were prepared for experiment. The performance tests are conducted with these rotors in order to investigate the effect of the splitter blades on performance and internal flow condition of mini centrifugal pump. On the other hand, a three dimensional unsteady numerical flow analysis was conducted to investigate the change of the internal flow according to the rotor rotation. It is clarified from the experimental results that the performance of the mini cen- trifugal pump is improved by the splitter blades. The blade-to-blade low velocity region was suppressed in the case with the splitter blades. In addition to that, the unsteady flows near the volute casing tongue were suppressed due to the splitter blades. In the present paper, the performance of the mini centrifugal pump is shown and the un- steady flow condition is clarified with the results of the numerical flow analysis. Furthermore, the effects of the splitter blades on the performance and the unsteady internal flow condition are investigated.

The Effect of Blade Outlet Angle on Performance and Internal Flow Condition of Mini Turbo-Pump

Mini turbo-pumps having a diameter smaller than 100mm are employed in many fields;automobile radiator pump,ventricular assist pump,cooling pump for electric devices,washing machine pump and so on.Further,the needs for mini turbo-pumps would become larger with the increase of the application of it for electrical machines.It is desirable that the mini turbo-pump design is as simple as possible due to restriction to make precise manufactures.But the design method for the mini turbo-pump is not established because the internal flow condition for these small-sized fluid machineries is not clarified and conventional theory is not conductive for small-sized pumps.Three types of rotors with different outlet angles are prepared for an experiment and a numerical analysis.The performance tests are conducted with these rotors in order to investigate the effect of the blade outlet angle on performance and internal flow condition of mini turbo-pumps.It is clarified from the experimental results that head of the mini turbo-pump increases and maximum efficiency flow rate shifts to larger flow rate according to the increase of the blade outlet angle,however the maximum efficiency decreases with the increase of it.In the present paper,the performance of the mini turbo-pump is shown and the internal flow conditions are clarified with the results of the experiment and the numerical flow analysis.Furthermore,the effects of the blade outlet angle on the performance are investigated and high performance design with simple structure for the mini turbo-pump would be considered.