CAJ | 학술논문

构建了一套基于运动嵌套网格技术和可压缩 RANS 方程的旋翼翼型非定常流动特性模拟的高效、高精度的 CFD 方法。首先，发展了基于 Poisson 方程求解的围绕翼型的粘性贴体正交网格生成方法，并提出了基于最小距离法（MDM）改进策略的运动嵌套网格生成方法，克服了弹簧法可能导致网格畸变的不足；其次，为准确模拟由湍流分离和气流再附引起的气动力的迟滞效应，基于 RANS 方程、双时间方法和高阶插值格式，建立了旋翼翼型非定常气动特性分析的高精度数值方法，并采用能够较好捕捉气流分离现象的 S-A 湍流模型；再次，针对旋翼后行桨叶动态失速时桨叶剖面来流速度较低、迎角较大的特点，为解决低来流速度时 L-B 半经验模型在旋翼翼型非定常动态失速计算中的局限性，并克服可压缩方程对低速流场计算收敛困难和精度低的问题，建立了基于 Pletcher-Chen 低速预处理方法、FAS 多重网格法和隐式 LU-SGS 方法相结合的高效数值方法。应用发展的方法，分别针对NACA0012、SC1095旋翼翼型静态和轻度、深度动态失速进行计算，精确捕捉了气动力迟滞效应以及翼型前缘脱体涡的产生、对流和脱落过程，验证了本文方法的有效性；最后，着重针对 NACA0012动态失速状态，开展了振荡参数对旋翼翼型非定常动态失速特性影响的分析，研究结果表明翼型迎角平均值、振幅及减缩频率的变化均能引起迟滞效应的改变并使得气动力峰值发生有规律的前、后移现象等。
구건료일투기우운동감투망격기술화가압축 RANS 방정적선익익형비정상류동특성모의적고효、고정도적 CFD 방법。수선，발전료기우 Poisson 방정구해적위요익형적점성첩체정교망격생성방법，병제출료기우최소거리법（MDM）개진책략적운동감투망격생성방법，극복료탄황법가능도치망격기변적불족；기차，위준학모의유단류분리화기류재부인기적기동력적지체효응，기우 RANS 방정、쌍시간방법화고계삽치격식，건립료선익익형비정상기동특성분석적고정도수치방법，병채용능구교호포착기류분리현상적 S-A 단류모형；재차，침대선익후행장협동태실속시장협부면래류속도교저、영각교대적특점，위해결저래류속도시 L-B 반경험모형재선익익형비정상동태실속계산중적국한성，병극복가압축방정대저속류장계산수렴곤난화정도저적문제，건립료기우 Pletcher-Chen 저속예처리방법、FAS 다중망격법화은식 LU-SGS 방법상결합적고효수치방법。응용발전적방법，분별침대NACA0012、SC1095선익익형정태화경도、심도동태실속진행계산，정학포착료기동력지체효응이급익형전연탈체와적산생、대류화탈락과정，험증료본문방법적유효성；최후，착중침대 NACA0012동태실속상태，개전료진탕삼수대선익익형비정상동태실속특성영향적분석，연구결과표명익형영각평균치、진폭급감축빈솔적변화균능인기지체효응적개변병사득기동력봉치발생유규률적전、후이현상등。
A high-efficiency and high-precision CFD method for simulating the unsteady dynamic stall of rotor airfoil has been established based on moving-embedded grid and compressi-ble RANS equations.Firstly,the generation method of viscous and orthogonal body-fitted grid around the rotor airfoil is developed by solving Poisson equations.Meanwhile,aiming at overco-ming the shortcoming of spring simulation approach which may result in the distortion of grid,an improved Minimum Distance Method is proposed to generate the embedded grid around airfoil. Secondly,in order to simulate the hysteresis effect of aerodynamic forces caused by the turbu-lence separation and re-attachment of the flow,a high-precision method on the analysis of unsteady aerodynamic characteristics of rotor airfoil is developed by employing RANS equations and dual-time method.The S-A turbulence model is employed to capture the separation phenomenon of flow around airfoil.Thirdly,according to the conditions of low-speed inflow and high AOAs of the retreating blade,together with the limitation of L-B semi-empirical model on the calculation of unsteady dynamic stall of airfoil,a combination method of Pletcher-Chen preconditioning, FAS multigrid approaches and implicit LU-SGS scheme is established to overcome the problems of convergence difficulty and insufficient precision of compressible equations.The steady,mild and deep dynamic stall cases of NACA0012 and SC1095 rotor airfoils are calculated using this pre-viously mentioned method,the hysteresis effect and the formation,convection,shedding of the vortical disturbance are well captured,the effectiveness of numerical simulation method on dynamic stall is verified.Finally,focus on the deep stall of NACA0012 airfoil,the influence ana-lyses of parameters on the unsteady aerodynamic forces of rotor airfoil are carried out,and the results demonstrate that the exchanges of averaged AOA,amplitude and reduced frequency may cause a variational hysteresis effect and regularly changes of peak value of aerodynamic force.