分析了刷式密封吹下效应理论模型,建立基于arbitrary Lagrange-Euler(ALE)流固耦合方法的刷式密封吹下效应三维瞬态数值模型,在验证数值模型准确性的基础上,分别研究了刷丝轴向、径向和截面变形特性,量化分析了刷丝径向吹下量,揭示了刷式密封吹下效应诱发机理.研究表明:刷式密封吹下效应会减小刷丝径向间隙,考虑吹下效应可以更加准确地计算泄漏量.刷式密封吹下效应是伴随刷丝扰动的非定常变形形式,刷丝自由端相比于后挡板径向中部和末端的刷丝截面,其吹下效应和刷丝扰动均较强.随着进出口压比的增加,刷式密封刷丝在具有更大径向吹下量的同时也伴随着更强的刷丝扰动,在研究工况下,2、3和4进出口压比下的刷丝束中部刷丝最大径向吹下量分别为0.004、0.010mm和0.019mm.刷丝具有一定的周向倾角和刷丝束区域的径向压力梯度是诱发刷式密封吹下效应的初始条件,且刷丝间的法向正压力和切向摩擦力会进一步影响吹下效应.增大刷丝周向倾角可以减弱刷式密封吹下效应.

多级刷式密封级间压降分配直接影响刷式密封的封严特性和使用寿命,现有多级刷式密封结构存在各级压降不均衡导致密封提前失效的问题.本文建立多级刷式密封三维实体流固耦合求解模型,设计搭建多级刷式密封实验装置,在数值计算与实验测试结果相互验证的基础上,研究了工况参数与结构参数对多级刷式密封级间压降分配的影响规律,揭示了多级刷式密封级间压降不均衡性的产生机理.研究结果表明:在本文研究工况下,相同结构的两级刷式密封各级压降占比分别为32％～35％和65％～68％,三级刷式密封各级压降占比分别为21％～27％、27％～32％、41％～52％,多级刷式密封各级承担压降逐级增大,进出口压比对级间压降分配影响不大;增大刷丝束与转子表面间径向间隙、刷丝之间间隙以及后挡板高度均可改善各级压降分配,同时也会增加泄漏量;影响多级刷式密封级间压降均衡性的主要原因是逐级不均匀增大的体积流量,各级压降随体积流量逐级不均匀的增加而增大;增大下游级流道截面积可有效降低体积流量,平衡多级刷式密封各级压降.本文研究结果为多级刷式密封结构设计提供了理论依据.

现有刷式密封流固耦合求解模型因刷丝变形接触导致网格畸变而难以计算.本文提出了基于ALE(Arbitrary Lagrange-Euler)流固耦合方法考虑刷丝变形接触的三维瞬态双向流固耦合求解模型,设计搭建了刷式密封泄漏特性和可观测刷丝运动轨迹的实验装置.实验研究了刷式密封刷丝运动状态对泄漏特性的影响,不同压比条件下的泄漏特性变化规律,在验证刷式密封流固耦合求解模型准确性基础上,数值分析了不同时刻刷式密封速度分布与刷丝运动状态,并研究了不同结构参数对泄漏特性的影响规律.研究结果表明:基于ALE流固耦合方法解决了传统刷式密封求解模型因刷丝变形接触导致网格畸变而难以计算的问题,可准确计算刷式密封流场特性和力学特性;刷式密封刷丝吹下效应会降低泄漏量,刷丝颤振现象主要发生在气流入口处的前排刷丝域,会引起泄漏量增大,在气流力作用下,刷丝束轴向厚度变小,有利于减小泄漏量;在本文研究条件下,刷丝固定端与自由端的中间部位最先发生变形,随着时间的变化,气流速度逐渐趋于稳定,最大速度出现在末排刷丝与后挡板接触位置,刷丝自由端变形最大;刷式密封泄漏量随径向密封间隙的增大而增大,与径向密封间隙0mm时相比,径向密封间隙0.2mm时泄漏量增加了51.6％～62.8％.随着刷丝排数的增大,泄漏量逐渐减小,当刷丝排数大于25排时,其对泄漏量影响较小.随着刷丝间隙、刷丝与后挡板之间的轴向间隙、后挡板保护高度的增大,泄漏量先逐渐增大后趋于平缓.

刷式密封刷丝运动变形引起的泄漏损失、刷丝断裂等问题较为突出.本文分析刷式密封刷丝运动变形理论模型,设计搭建刷式密封刷丝变形与振动特性观测实验装置,设计加工了3种周向倾角的低滞后型刷式密封实验件,实验观测并研究刷式密封刷丝轴向变形特性,刷丝吹下效应、刷丝分层和刷丝振动特性,揭示刷式密封刷丝运动状态.研究结果表明,在进出口压比1.5～4工况下,刷式密封刷丝自由端轴向变形量随着压比的增大而近似线性增加,周向倾角对刷丝轴向变形影响不大.刷式密封前排刷丝吹下效应明显强于后排刷丝,随着周向倾角的增大,刷式密封刷丝吹下效应逐渐减弱,在本文研究工况下,周向倾角为50°、55°和60°的刷式密封刷丝最大吹下量分别为0.60、0.45和0.34 mm.刷式密封刷丝产生分层现象的主要原因是在气流力的作用下,刷丝束轴向产生变形,刷丝束自由端在不相等的转子表面轴向摩擦力作用下,刷丝束进一步产生不同步的变形量,导致刷丝束出现间隙进而形成刷丝分层现象.刷丝振动主要发生在刷丝密度相对松散的区域,且随着压比的增大而增强,刷丝自由端位移随时间呈振荡变化,其在轴向的振幅大于周向的振幅.

以发动机风扇转子为研究对象,参考适航标准完成真空、旋转状态下的风扇转子鸟撞击试验.对试验后的风扇转子叶片进行损伤分析,试验结果显示:风扇转子叶片出现了叶尖断裂,前缘撕裂、凹陷、卷边,凸肩错位、搭接,掉块等损伤.利用PAM-CRASH冲击分析软件进行仿真分析,仿真结果显示:鸟弹撞击模式、撞击过程、叶片及凸肩损伤模式与试验结果基本一致,叶片最大损伤与试验结果基本相同,但损伤叶片数量少于试验结果.通过试验及仿真分析完成了该发动机风扇转子鸟撞击能力考核,叶片损伤严重但仍在风扇机匣包容性控制范围内,不会出现高能碎片飞出从而影响飞机安全的情况.本文试验及仿真分析方法可为其他风扇转子类鸟撞击试验提供参考依据.

刷式密封刷丝接触变形引起的泄漏损失、刷丝断裂等问题较为突出,现有刷式密封流固耦合方法存在因刷丝接触引起网格畸变而难以计算的问题.提出基于ALE(Arbitrary Lagrange-Euler)流固耦合方法建立刷式密封刷丝接触变形特性三维瞬态求解模型,设计搭建刷式密封刷丝接触变形观测试验装置,设计加工基本型和有/无压力腔低滞后型共三种刷式密封试验件,在理论计算与试验测试结果相互对比验证的基础上,系统研究压比和刷式密封结构对刷丝接触变形和接触应力的影响,基于接触摩擦力量化分析比较三种刷式密封的滞后效应.研究结果表明,ALE流固耦合方法解决了传统刷式密封数值方法难以计算的问题,可准确计算刷式密封的流场特性与刷丝接触变形特性;在所研究工况下,无压力腔低滞后型刷式密封泄漏量和刷丝轴向变形量最大,其刷丝固定端接触应力也最大,基本型刷式密封泄漏量和刷丝轴向变形量最小但产生的滞后效应最强,有压力腔低滞后型刷式密封可以减弱刷丝变形和滞后效应,但末排刷丝与后挡板的接触应力最大,该位置易发生因应力集中而导致刷丝断裂.

针对工作状态下航空发动机止口连接结构工作可靠性问题,开展了不均匀温度场下止口连接结构过盈量变化的研究.建立了止口结构简化模型,基于热弹性力学理论,利用平衡微分方程、物理方程和几何方程,推导出不均匀温度场下止口过盈量变化的计算式;通过算例进行理论计算,结合有限元软件对计算结果进行仿真对比.结果表明:在一定温度场下,航空发动机止口连接结构实际过盈量理论损失高达63％,设计时应加以补偿.所得结论可为止口连接结构过盈量设计提供理论依据.

建立了基于三维实体建模的刷式密封传热特性求解模型,在验证数值模型准确性的基础上,分析了刷式密封流场与温度场分布特性,研究了压比、转速、干涉量和热流密度对刷丝最高温度的影响,揭示了刷式密封的传热机理.结果 表明:高温区主要集中在末排刷丝与转子面接触位置,刷丝的最高温度随着压比、转速、干涉量和热流密度增加而增大,其中干涉量对刷丝最高温度的影响最为明显.当干涉量从0.1 mm增至0.7mm时,刷丝的最高温度上升1.61倍;刷式密封热量的主要来源为刷丝与转子表面摩擦产生的热量,其传热形式包括导热和对流换热,摩擦热量通过导热形式进入刷丝和转子,当刷丝与转子之间的接触力增加时,摩擦热量增大,刷丝的最高温度升高,摩擦热量通过对流换热形式在流体和固体之间进行传递,热量散失主要形式为泄漏气流带走部分热量.

基于平行压气机理论,采用非定常、二维、无黏的积分型欧拉方程,以蒸汽吸入试验中产生的温度和压力组合畸变为边界条件,开展真实进气条件下温度和压力组合畸变对发动机影响的计算方法研究.在保证畸变强度、高温区范围、低压区范围等特征不变的前提下,对畸变图谱进行规则化等效转换,同时协调温度和压力畸变图谱,使两者可以进行相互叠加计算.结果 表明:当周向子发动机数量大于2时,子发动机数量对计算结果影响不大;组合畸变对风扇、压气机压比影响规律与单独的压力畸变相同;与试验的推力损失对比显示,对畸变图谱进行等效规则化转换,可以用于真实组合畸变的计算.

针对航母舰载机蒸汽弹射器滑道逸散水蒸气的传热与凝结现象,建立空气/水蒸气/凝结水三流体的流动、传热及相变过程数学模型.其中具有描述水蒸气复杂过程热力学行为的IAPWS模块以自定义程序并入模型中,利用Eulerian-Eulerian模型加入质量传递、能量传递和动量传递方程来实现水蒸气流动过程中传热传质问题的研究;在质量传递模型中加入液滴成核和生长理论模型,研究水蒸气的凝结过程.结果表明:在流动过程中,空气-水蒸气-液态水三流体混合,温度逐渐趋于一致;进气道入口压力越低,发动机对水蒸气的吸入量越大;伴随空气流动的水蒸气温度不断下降,并且会因有凝结现象发生;随着空气来流速度的增加,水蒸气的吸入量也会呈现先增加后下降的趋势;随着水蒸气流速的提高,水蒸气进气量上升,空气所占比例有所下降,但仍然是主导地位.

为了探讨半椭圆槽改善圆孔射流气膜冷却机理,数值模拟研究了圆孔-半椭圆型槽组合结构下游流场、温度场及气膜冷却效率.分析了不同吹风比下半椭圆槽深度对气膜冷却特性的影响.结果表明:吹风比0.5和1.5时,和锯齿槽相比,半椭圆槽更容易形成反向对漩涡,展向平均气膜冷却效率提高5％～119％.随着半椭圆槽深度的增加,孔间区域的气膜冷却效率提高,展向气膜冷却效率分布更均匀.吹风比0.5时,槽深度对半椭圆槽展向平均气膜冷却效率的影响很小,三种槽深的差距在15％以内.吹风比1.5时,半椭圆槽深度为0.5倍孔径的展向平均气膜冷却效率最佳,分别比槽深度为0.25倍和0.75倍孔径的半椭圆槽高55％～107％和2％～16％.

篦齿封严风阻温升效应引起的热负荷对航空发动机涡轮叶片冷气系统有着重要的影响.采用理论分析、数值计算与实验相结合的方法系统地研究了篦齿封严的风阻温升特性.首先,对篦齿封严风阻温升特性进行了理论分析,设计搭建了篦齿封严风阻温升特性实验台,建立了基于RNG(Re-Normalization Group) k-ε湍流方程的篦齿封严风阻温升数值求解模型.然后,研究了篦齿封严流场特性、泄漏特性和风阻温升特性,并将理论计算、数值仿真与实验测试结果相互对比分析,研究了压比、转速等因素对篦齿封严风阻温升特性的影响规律,揭示了篦齿封严的风阻温升效应产生的机理.结果表明:高低齿篦齿封严结构减弱了篦齿封严的透气效应,增强了篦齿封严的动能耗散,有利于降低篦齿封严的泄漏量;在所研究的工况下,转速低于2 000 r/min时,风阻温升效应较小,转速在2 000～6 000 r/min时,风阻温升随转速的升高而增大,温升值最高可达12.87 K;压比的增大会加强气流的对流换热,转速为6 000 r/min时,压比从1.1增加到1.3,温升值下降了7K左右;风阻温升产生的主要原因是流经封严间隙的黏性气流与高速旋转的转子相互摩擦产生热量,气流吸收这部分摩擦热导致温度升高,转子转速越高,风阻温升效应越强.所研究的篦齿封严风阻温升特性为航空发动机内通道气流热负荷分析提供了理论依据.

概述了航空发动机不同联接结构的研究情况,重点针对螺栓联接结构动力学建模(包括对方形联接件和法兰结构的动力学建模)、刚度计算方法、接触非线性、应力应变机械特性和试验研究情况,以及螺栓联接结构在转子系统中的应用展开详细论述,分析了螺栓联接结构对旋转状态和动力学响应的影响,并对多螺栓装配体结构装配性能研究进行论述.提出应建立完备的螺栓联接动力学特性研究理论,开展螺栓联接结构与其相应的装配体整体结构、螺栓联接动刚度和螺栓联接装配对结构动力学特性影响的深入研究.

Aiming at the problem of unbalanced feature reproduction of rotor system, a method of model reconstruction based on dynamic similarity criteria was presented. According to the vibration differential equation of the rotor system, the similarity relationship among rotor shaft, disk, flexible support and unbalance amount was established by the integral simulation method and dimensional analysis method. In the light of the similarity relationship, the dynamic similarity model of the prototype unbalanced rotor system was designed and the correctness was verified using finite element method. The least square method was used to identify the unbalance of the prototype and model rotor test bench system. The process of reproducing the unbalanced features was given. The effectiveness of the unbalanced feature reproduction design method was verified by experiment. Unbalanced feature reproduction method of rotor system was summarized based on dynamics similarity relationship.

To investigate the effects of internal roughness in precision casting turbine blade on impacting heat transfer characteristics, heat transfer coefficient of different scale double-wall were simulated at internal roughness of 0μm, 10μm, 20μm and 30μm and at Reynolds number range from 1 × 104 to 5 × 104. Heat transfer coefficients on target plate of large-scale at roughness of 0μm were measured by transient liquid crystal technolo?gy. The results show that the numerical results of heat transfer coefficients on target plate of large scale agree well with the experimental data. Heat transfer coefficients of smooth plate for two different scales are substantially the same after dimensionless processing. Heat transfer coefficients on target plate for small scale increase as the sur?face roughness increases. This influence of roughness becomes more obvious as Reynolds number increases , as Reynolds number varies from 1 × 104 to 5 × 104, the area-averaged heat transfer coefficients on target plate with the roughness of 30μm for small scale are higher 6%~48%than the result of the smooth target plate. The influ?ence of roughness on heat transfer coefficients for the large scale is weak.

In order to explore the performance of improving film cooling by sawtooth compared to transverse slot,the flow and the temperature distribution,film cooling effectiveness of these two structures which have the hole pitches of 2,3,4,respectively,were numerically investigated at blowing ratios of 0.5 and 1.5,respec?tively. The results show that the computational values of film cooling effectiveness by transverse slot agree with the experimental data. The sawtooth slots have a strong ability of the spanwise spreading of the coolant compared to the transverse slots. With the increases of hole pitches,the vortex pairs existing hole center line become weak and the additional vortex pairs easily appear at the midspan region,resulting in that film cooling effectiveness of sawtooth slot is much higher than that of transverse slot. At blowing ratio of 0.5,the surface averaged film effec?tiveness of sawtooth slot is higher 27%,35%and 42%,respectively than that of transverse slot with hole pitch?es of 2,3 and 4. At blowing ratio of 1.5,the surface averaged film effectiveness of sawtooth slot is higher 27%, 95%and 151%than that of transverse slot with hole pitches of 2,3 and 4.

To investigate the effects of internal surface roughness of precision casting turbine blade on heat transfer of pin-fin with lamilloy structure,the heat transfer coefficient of the pin in typical lamilloy were simulated,with internal surface roughness of 0 μm,10 μm,20 μm and 30 μm,at Reynolds number range from 1 × 104 to 5 × 104.The results show that,the influence of the internal surface roughness on heat transfer of the pin-fin mostly concentrates on the windward side.The average heat transfer coefficient on the pin increases with the surface roughness,and this influence becomes more obvious as the Reynolds number increases.When the Reynolds number varies from 1 × 104 to 5× 104,the area-averaged heat transfer coefficient on the pin-fin with internal surface roughness of 30 μm are 13％ to 134％ higher than that on the smooth pin.

针对由薄壁构件相似模型试验结果预测原型动力学特性的问题,建立了统一的数学模型,并基于方程分析法推导了动力学相似关系.通过对薄壳单元进行受力分析,推导得到薄壁构件的微分方程,并通过微分方程得到完全几何相似模型可准确预测原型动力学特性的相似关系.在建立薄壁构件结构参数对固有频率的敏感性与相似因子指数的比值关系基础上,提出薄壁构件不完全几何相似模型与原型的动力学相似关系(即畸变相似关系)的确定方法.最后给出基于敏感性分析的薄壁构件精确畸变相似关系设计流程,为薄壁构件相似试验模型的设计及动力学特性的预测提供参考.

为进一步提高鼠笼式弹性支承结构支承刚度设计的准确性,同时最大限度地减小鼠笼受到的最大应力,在相关研究的基础上,基于参数化建模思想,并结合有限元优化技术提出分步优化设计方法.采用鼠笼式弹性支承的刚度和应力计算公式并结合加工装配条件初定1组满足设计要求的结构参数值;建立鼠笼式弹性支承的有限元优化模型,并将初定的结构参数值代入到有限元优化模型作为优化的初始迭代值,同时以鼠笼笼条的长度和厚度为优化参数,经过迭代计算得到满足工程需求的结构参数.该方法可提高设计精度,节省设计时间.最后,结合具体算例验证了优化设计方法的有效性和实用性.

In order to explore the film cooling performance of cylindrical holes attached with W shape slots,the flow field,the temperature field and the film cooling effectiveness distribution on the downstream wall of W shape slots and transverse slots were studied by numerical simulation. Influences of the depths of the W shape slot on the film cooling effectiveness were analyzed. The results show that the spanwise averaged film cool-ing effectiveness of the W shape slot model increased by 70%~130%compared with that of the transverse slot. With the increase of W shape slot depths,the rotating vortices are weakened in the downstream of the film cool-ing hole exit,and the additional vortices are strengthened in the downstream of both sides of the hole,eventual-ly forming a pair of reverse counter-rotating vortices. At the low blowing ratio of 0.5,the difference of the span-wise averaged film cooling effectiveness is less than 8% among the three depths of W-shape slots. At the high blowing ratio of 1.5,the spanwise averaged film cooling effectiveness of the slot depth 0.5D (D means film hole diameter) case is much higher than that of 0.25D by 75%~150%. However,the spanwise averaged film cooling effectiveness of the slot depth of 0.5D case is close to 0.75D case,in which the difference is less than 3%.