| 1. | The unsteady flow around helicopter rotor in forward flight was numerically simulated by solving 3 - d euler ' s equations
采用三维非定常欧拉方程数值模拟了旋翼前飞非定常流动。 |
| 2. | The diamond shaped canopy provides 85 % frontal coverage ; the crosswind compensation effect can also be clearly felt during fast forward flight
钻石状菱形机身包覆性达到85 %以上，高速航道飞行时，针对侧面抗风之特性尤其明显。 |
| 3. | By means of dual - time stepping method and moving grids technique , we solved the 3 - d unsteady euler ' equations for helicopter rotor in forward flight , and obtained the near - field hsi noise
为了多桨旋翼旋转、变距等复合运动的准确描述，采用了多块分区运动网格技术。 |
| 4. | Combining cfd technology and aeroacoustic theory in time domain , the high - speed impulsive ( hsi ) noise of helicopter rotor in hover and in forward flight was predicted and investigated
本文结合cfd (计算流体力学)技术与气动噪声时域理论，求解直升机旋翼悬停和前飞流场及流场气动噪声。 |
| 5. | The acoustic noise generated by the rotate point source , uh - 1h rotor in hover and ah - l / ols in forward flight were calculated , and the computed results from several methods were compared with each other and with the experimental data
采用旋转点源、 uh - 1h悬停旋翼、 ah - 1 / ols前飞旋翼作为算例，对所采用的各种噪声预测方法进行了比较。 |
| 6. | In 1975 , nimitz joined the atlantic fleet , ending enterprise s reign as the largest warship in the world . the carrier s flight deck is generally the same as that of the kitty hawk , but with the cut - off forward flight deck first seen on the john f . kennedy
该舰总长.米，水线长米，舰宽.米，飞行甲板长.米，飞行甲板宽.米，斜角飞行甲板长.米。 |
| 7. | For the validation of the total model , the comparison of trim results in hover / forward flight was made with the popular software of flightlab , and linearization matrixes were compared with helisim , they both show the coordination results
本文利用所建立的模型，根据ads 33规范要求，逐条计算了（ 3 3 ）节的内容，并对样例直升机进行了开环状态下的部分品质等级的评估工作。 |
| 8. | In chapter 3 , the non - linear equation was linearized with the jacobi matrix , and then the linearized equation was transformed into fixed frame to analyze the stability problem with eigenvalue method ( on - ground or hovering ) or floquet theory ( forward flight ) . meanwhile , the equation was perturbed by sweep frequency excitation from steady state to get transit decay of lag response which was then transformed into fixed frame with a numerical fourier coordination transformation ( fct ) . the fixed frame response along with the body response was analyzed via an fft to determine modal frequencies
然后,在稳态响应的基础上利用雅各比矩阵对非线性方程进行了线化,线化后的方程利用多桨叶坐标变换转换到固定系下后,利用直接特征值分析(地面、悬停)或floquet理论(前飞)对系统进行了稳定性分析;同时,对系统进行了瞬态响应分析;在系统达到稳态的基础上进行扫频激励,用fft变换求得系统频率,进而用移动矩形窗方法分析得到系统的阻尼。 |
| 9. | The new model captures important behavior such as reduced damping in forward flight due to dual - frequency motion . it also captures the correct force - displacement ( time domain ) hysteresis behavior . the new inter - blade damper nonlinear kinematics model confirms experimentally observed results reported in the literature : certain damper attachment offsets can lead to reduced damper 1 / rev motion and forces
数值结果表明：本文的粘弹减摆器模型与以往的模型相比有很大的改进，可以准确地计算减摆器在时域内的力位移迟滞曲线，也可以很好的描述直升机前飞过程中减摆器出现的双频特性。 |
| 10. | The main factors which affected the flight stability quality included : forward flight speed , slung - load and helicopter mass ration , slung - load aerodynamic forces and cable length , etc . through adjusting the above structure and performance parameters , rational flight parameters can be decided , which can ensure the safe helicopter mission operations of the slung - load flight
影响飞行品质稳定性要求的主要因素为:直升机飞行速度、吊挂物/直升机质量比、吊挂物气动特性、吊挂钢索长度等。通过对上述结构参数、性能参数的调节,可确定合理、经济的飞行参数,保证安全、高效的完成直升机机外吊挂飞行运输任务。 |
