阵风发生器是阵风响应风洞试验的关键设备.针对叶片式阵风发生器的运行特点,通过简化的定常涡升理论,推导出阵风发生器下游流场Y向风速的计算公式.以0.55?m×0.4?m低速风洞(声学引导风洞)为实验平台,系统地研究了阵风发生器的设计参数(叶片弦长、数目、间距)和运行参数(叶片摆幅和摆动频率、来流速度)对阵风流场风速极值的影响.研究表明:推导的简化公式能够解释阵风发生器各设计和运行参数变化后,其下游流场Y向风速的变化机制,可在阵风发生器设计时对其产生的阵风流场进行简单预估;从增大阵风发生器下游流场Y向速度极值的角度出发,增加叶片数目比增大叶片弦长更能增大Y向速度;在叶片失速前,增大叶片摆幅比增大叶片摆动频率更能增大Y向速度;采用多组叶片的阵风发生器,叶片间距不能太小,否则会导致等效升力系数下降,当叶片间距为1.2倍弦长时,能够获得最大的Y向速度极值.本文研究工作可为其他风洞的阵风发生器设计提供参考.

Combining the fan aerodynamic efficiency with the wind tunnel pressure loss coefficient, a new equation which points out the inherent relationship of the fan blade setting angle, fan rotating speed and gas flow rate in wind tunnel circuit is derived according to the two-dimensional flow theory of the axial fan rotor blades and the aerodynamic characteristics of the low speed wind tunnel. So a new method for setting angle adjustment of fan rotor blade to satisfy the fan performance at off-design point by getting the test results of fan operation parameters but without the fan total pressure rise in the low speed wind tunnel is developed. Flowing the new method, the setting angle adjusting value of fan rotor blade was provided only with the fan rotating speed and flow velocity in the test section of a low speed wind tunnel directly before the fan setting angle altered, the adjusting target was achieved by the new blade setting angle successfully and the time and cost of the wind tunnel commissioning test were saved. The test results show that, after increasing the fan rotor blade setting angle by 4.5 degrees, when the flow velocity in the wind tunnel test section reaches 60 m/s, the fan rotating speed is 570 r/min, the deviation from the predicted fan rotating speed value of 575 r/min is 0.9%. For the same test section flow velocity, the predicted value of the fan rotating speed is in a good agreement with the real value, it proves that this method is reliable and accurate in practical application.

利用风洞试验的方法对某型直升机的防砂滤试件在低温环境下的结冰情况进行了研究.试验过程中,运行0.3m×0.2m结冰风洞制冷系统降低风洞内部气流温度,通过优选风洞喷雾系统的两相流喷嘴位置,合理设置喷嘴入口的水压与气压来满足不同试验段风速下的液态水含量及水滴直径要求.结果表明,防砂滤试件在低风速下会发生结冰现象,使得试件进出口压力损失增大,影响试件性能,而在高风速环境中结冰情况则明显改善.另外,试验同时发现防砂滤试件的结冰起始于试件的中部偏下游的位置,而后再逐渐向上游蔓延.文中应用势流分析方法对这一现象进行了分析.

利用用于风洞轴流风扇设计的“任意涡”风扇设计方法,以长虹某款空调室外机轴流风扇为对象进行改进设计,并将改进前后的风扇在焓差实验室进行测试.改进后的风扇经调试后,气动效率在原风扇30.9％的基础上提升至38.7％,验证了此风扇设计方法的可行性,提高了空调能效比.

On the basis of the master curve of boundary layer displacement thickness for low speed wind tunnel contraction obtained from numerical research,the distribution of the displace-ment thicknessδ* for the pilot aeroacoustic wind tunnel(PAWT)’s contraction is derived.Ac-cordingly,we redesigned the contraction contour,gave the deviation after correction,fabricated the test article,and conducted the numerical simulation and experimental study.The numerical results show that,although the boundary layer of the contraction was very thin and the maxi-mumδ* was only 0 .5% or so of the test section hydraulic diameter,the correction effect was re-markable.After the correction,for both open and closed test sections,the dynamic pressure non-uniformity was reduced,the flow-deviation angle decreased,and the flow field quality was im-proved.At the contraction exit,the near wall velocity was overshoot due to the reverse pressure gradient.But after entering the straightness section,the dynamic pressure non-uniformity and the flow angle decreased sharply.After the contraction,there is a straight section whose length is 1 6 .7% of contraction,which is very helpful for improving the flowfield quality.Using mova-ble measuring device,pitot tube and hotwire anemometer,we measured the dynamic pressure and velocity before and after the correction.The measuredδ* coincides with the theoreticalδ*, and the effect of boundary correction is verified experimentally.Based on the measured velocity distribution,it can be inferred that the boundary layer in the contraction of PAWT is laminar, without transition from laminar to turbulent flow.

A pilot gust generator is as experiment object,by measuring the flow field of the gust generator in different situations with two dimension hot wire anemometer,the measurement scheme and online measuring angle correction,and the calculation of the gust amplitude and flow fluctuation are proposed.Experiment results show that online angle correction used can improve the accuracy and efficiency of two dimension hot wire in Y direction,phase analysis used can sat-isfy the calculate the amplitude and fluctuation of periodic gust.Gust amplitude is in direct ratio with the vane oscillation frequency of 4 ~ 15Hz,oscillation angle of 8°~ 30°,and vane chord length of 50~100mm.Unstability (velocity fluctuation at same phase)of the gust flow has a cer-tain linear relationship with the vane oscillation angle and wind speed,which increases while the vane oscillation angle and wind speed increase in the test range,at the same time,proper vane os-cillation frequency can decrease unstability.The conclusion is helpful for the gust generator de-velopment and flow field measurement in wind tunnel.

Arbitrary vortex method is used to design a high-performance low-noise fan for the acoustic pilot wind tunnel. In the design, a more well-distributed axial speed at the outlet of fan system is obtained by regulating the rotating speed distribution, the noise generated by rotor-stator interaction is reduced by matching more reasonable rotor-stator blade number and stator backward-swept angle. According to the results of the fan aerodynamic and acoustic experiments, the efficiency of the high-performance low-noise fan is 83.9% at its design point, which is an obvious improvement compared with the original fan setting in acoustic pilot wind tunnel(73%), meanwhile, the inlet noise of high-performance low-noise fan is 3dB(A) lower than the inlet noise of original fan, and the outlet noise of high-performance low-noise fan is 2dB(A) lower than the outlet noise of the original fan. The experimental results indicate that arbitrary vortex method has significant advantage in fan aerodynamic and acoustic performances.

This paper is the numerical investigation reports about field characteristic of fan section.First,it presents the control equations and boundary conditions for numerical simulation.Then the details of numerical results are given about velocity characteristics of fan section in 0.55m×0.4m low turbulence aero-acoustics wind tunnel.Conclusion could be got that numerical methods used could give rational results comparing with experiment data.Then,basing on the flow around rotor and stator,the flow mechanism inside fan section was analyzed.At last different fan models were study based on the numerical results.These parameters imposed influence on performance and flow mechanism of fan including the distance between rotor and stator,stator swept and leaned.Stator leaned could significantly reduce or eliminate rotor wake and tip separation,and could produce a more uniform velocity profile at exit.Conclusions state the importance and feasibility of CFD in aerodynamical design of fan section in wind tunnel.