Lightweight design of low speed wind tunnel model
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摘要: 风洞试验模型的设计和制造直接关系到风洞试验数据的准确性,对飞行器研制的周期和成本具有重要的影响。对低速风洞试验模型进行轻量化设计是获得可靠风洞试验数据和降低风洞试验成本的关键环节。采用复合材料蒙皮加框梁及增材制造结构,以某民机模型为研究对象,开展整体化、轻量化设计,应用有限元分析软件对设计结果进行强度校核和振动分析。结果表明,通过优化设计,与传统金属模型相比,模型设计重量降低50%以上;机翼采用复合材料蒙皮和复合材料加强筋结构,其强度可满足设计要求;对异形零件进行面向增材制造的轻量化设计,与基于复合材料制造的设计相比,可减重20%,制造周期缩短50%以上;模型轻量化设计后可提高模型-支撑系统固有频率。Abstract: Design and manufacturing of wind tunnel models are related directly to the accuracy of wind tunnel test data, and also influence period and cost of aircraft development. Lightweight design of low speed wind tunnel models is one of key points to obtain reliable aerodynamic data and lower testing cost. With the structure of frame and beam strengthened composite skins and the additional manufacturing parts, the integral and lightweight model of civil aircraft is designed. The finite element analysis is used to calculate the structure intensity and vibration analysis is conducted. It concludes that the weight of the model is reduced by 50% compared to that of the conventional metal model, and meanwhile the structure intensity of the model satisfies design requirements. The irregular shaped part is designed with additional manufacturing method, the weight of which is reduced by 20% and the manufacturing period is shortened by more than 50% compared to that for composite model. The inherent frequency of the model-support system is increased compared to that of metal model.
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Key words:
- wind tunnel model /
- composite /
- additional manufacturing /
- lightweight design
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表 1 模型设计输入条件
Table 1. Design input of model
Input Value Model scaling 1:7 Model weight < 500kg Testing wind speed 70m/s 表 2 最大气动载荷
Table 2. Maximum aerodynamic load
Aerodynamic
loadY
/NX
/NZ
/NMx
/(N·m)My
/(N·m)Mz
/(N·m)Y
/NValue 9400 900 2740 2670 1540 2270 9400 表 3 T300碳纤维单向带和平纹织物材料属性
Table 3. Material property of unidirectional prepreg and fabric for T300 composite
E1/GPa E2/GPa G/GPa ν Unidirectional prepreg 108 40 3.8 0.285 Fabric 46 46 2.3 0.064 注:E1,E2分别为0°、90°方向弹性模量;G为剪切模量;ν为泊松比。 表 4 金属模型与轻量化模型振动分析
Table 4. Vibration analysis for metal model and lightweight model
金属
模型轻量化
模型振动
形式固有频率
增加百分比一阶固有频率/Hz 3.3 4.9 侧向摆动 48% 二阶固有频率/Hz 5.2 8.4 侧向弯曲 61% 三阶固有频率/Hz 5.8 8.6 法向摆动 48% 四阶固有频率/Hz 10.1 13.4 法向弯曲 33% -
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