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11.
《中国航空学报》2021,34(5):120-128
With the explosive development of aerospace science, the design of the new generation airliner at higher speeds is attracting more attentions. To achieve this goal, it is necessary to achieve accurate prediction of the aerodynamic heating / force loads and successful reduction of drag and heat flux. As a remedy for the existing studies which are based upon the CFD and wind tunnel tests, this study presents a flight test for the drag and heat reduction spike technology. The principal goals of this flight test were to provide reference for verifying the accuracy of the prediction technology on ground and promote the development of the drag and heat reduction technology. By adopting the OS-X rocket, the TT-0 test vehicle designed by Shenyang Aircraft Design & Research Institute reached a maximum Mach number of 5.8 and a maximum altitude of 38 km. Hypersonic and supersonic pressure data by pressure scanning valves and heat fluxes by gauges at different locations were obtained successfully. Also, heat fluxes obtained by in-house CFD code are illustrated in comparison with the flight data. The results indicate that the numerical errors are large in most cases. More technologies, such as more CFD codes and more numerical procedures, should be adopted to conduct studies on this issue in the future. 相似文献
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针对J2摄动和大气摄动导致低轨编队卫星构型破坏的情况,基于高斯摄动方程给出了以平均轨道根数为被控制量的脉冲控制模型。利用法向脉冲调整轨道倾角和升交点赤经偏差,在轨道上2个位置施加径向和切向脉冲调整其余轨道根数偏差从而修正卫星编队构形。最后通过数值仿真验证了算法的简单性、有效性。 相似文献
14.
法向与展向电磁力可以有效调制湍流近壁流动及减少壁面摩擦阻力.为进一步揭示该方法的减阻机理,利用Fourier-Chebyshev谱方法,通过直接数值模拟(DNS),对槽道湍流的法向与展向电磁力控制和减阻问题进行了研究.结果表明,对于确定的流向波长λx+,存在最佳的电磁力强度St,使阻力降最大,最佳St与λx+成反比.法向与展向电磁力对湍流的控制过程实质上是一种由电磁力诱导的调制波对壁湍流的调制过程.在优化参数控制下,当法向与展向电磁力诱导的流场被用来调制固有的近壁湍流流场时,固有流场和诱导流场同时受到调制.在这种调制波作用下,调制流场逐渐主宰壁面边界层,这导致了壁面阻力的下降,平均减阻率最高可达8%. 相似文献
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推阻特性是吸气式飞行器研制中最为关注的气动特性问题之一.为研究通气模型内流道阻力特性,在中国空气动力研究与发展中心(CARDC)超高速所的1m高超声速风洞上开展了吸气式飞行器通气模型内流道阻力直接测量技术研究.研究选取吸气式飞行器的一个内流道模块为研究对象,通过将内流道模块与模型其余部分进行分离设计、采用特种应变天平直接测量模型内流道气动力的方法得到通气模型内阻,同时进行了干扰因素分析和试验数据修正方法研究,开展了Ma=4条件下的内流道阻力测量试验并给出了典型试验结果.试验结果表明,通气模型内阻随攻角和喉道高度变化而变化. 相似文献
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为了分析大气阻力摄动对卫星编队队形的影响,利用相对轨道根数法推导了包含大气阻力摄动的卫星编队相对运动的状态转移方程。仿真结果表明当几何形状和质量不同的两颗卫星在低轨道做编队飞行时,大气阻力摄动对编队队形的影响很大而不能忽略;当主卫星的半长轴相等时,主卫星轨道的偏心率越大编队飞行受大气阻力摄动的影响也越大;大气阻力摄动主要影响编队飞行迹向相对距离。 相似文献
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Altab Hossain Ataur Rahman Jakir Hossen A.K.M.P. Iqbal M.I. Zahirul 《Aerospace Science and Technology》2011,15(8):595-605
This paper describes the potentials of an aircraft model without and with winglet attached with NACA wing No. 65-3-218. Based on the longitudinal aerodynamic characteristics analyzing for the aircraft model tested in low subsonic wind tunnel, the lift coefficient (CL) and drag coefficient (CD) were investigated respectively. Wind tunnel test results were obtained for CL and CD versus the angle of attack α for three Reynolds numbers Re (1.7×105, 2.1×105, and 2.5×105) and three configurations (configuration 1: without winglet, configuration 2: winglet at 0° and configuration 3: winglet at 60°). Compared with conventional technique, fuzzy logic technique is more efficient for the representation, manipulation and utilization. Therefore, the primary purpose of this work was to investigate the relationship between lift coefficients and drag coefficients with free-stream velocities and angle of attacks, and to illustrate how fuzzy expert system (FES) might play an important role in prediction of aerodynamic characteristics of an aircraft model with the addition of winglet. In this paper, an FES model was developed to predict the lift and drag coefficients of the aircraft model with winglet at 60°. The mean relative error of measured and predicted values (from FES model) were 6.52% for lift coefficient and 4.74% for drag coefficient. For all parameters, the relative error of predicted values was found to be less than the acceptable limits (10%). The goodness of fit of prediction (from FES model) values were found as 0.94 for lift coefficient and 0.98 for drag coefficient which were close to 1.0 as expected. 相似文献
20.
Willy Benz 《Space Science Reviews》2000,92(1-2):279-294
The physics of low velocity collisions (5 m/s to 40 m/s) between basalt bodies ranging in size from 1 m to 10 km is studied
in an effort to investigate the early phases of planetesimal accretions. To assess the importance of the internal structure
of planetesimals on the outcome of the collisions, we model them either as solid spheres or as rubble piles with a filling
factor of 0.5.
The collisions are simulated using a three dimensional Smooth Particle Hydrodynamics (SPH) code that incorporates the combined
effects of material strength and a brittle fragmentation model. This approach allows the determination not only of the mass
of the largest fragments surviving the collisions but also their dynamical characteristics.
We find that low velocity collisions are for equal incoming kinetic energy per gram of target material considerably more efficient
in destroying and dispersing bodies than their high velocity counterparts. Furthermore, planetesimals modeled as rubble piles
are found to be characterized by a disruption threshold about 5 times smaller than solid bodies. Both results are a consequence
of a more efficient momentum transfer between projectile and fragments in collisions involving bodies of comparable sizes.
Size and shape dependent gas drag is shown to provide relative collision velocities between similar meter-sized objects well
in excess of the critical disruption threshold of either rubble piles or solid bodies. Unless accretion can proceed avoiding
collisions between bodies of similar masses, the relative weakness of bodies in this size range creates a serious bottleneck
for planetesimal growth.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献