水滴平均体积直径(Mean volumetric diameter,MVD)和液态水含量(Liquid water content,LWC)是两个影响飞机结冰的重要气象参数,但在实际中难以准确测得,如果能够实时、准确地获取这两个参数可以为积冰预测和飞机适航认证标准的建立提供...水滴平均体积直径(Mean volumetric diameter,MVD)和液态水含量(Liquid water content,LWC)是两个影响飞机结冰的重要气象参数,但在实际中难以准确测得,如果能够实时、准确地获取这两个参数可以为积冰预测和飞机适航认证标准的建立提供一些指导。文中提出了一种基于遗传算法优化神经网络的结冰气象参数预测模型。以不同测点组合的冰厚和结冰速率、环境温度、飞行速度和机翼迎角为输入参数,结冰气象参数MVD和LWC为输出参数,构建遗传算法优化的结冰气象参数预测模型,并通过预测模型对数值计算测试组数据和结冰风洞实验数据的结冰气象参数进行预测。结果表明,基于遗传算法优化Elman神经网络的预测模型对结冰气象参数的测试组预测相对误差在10%以内,实验数据相对误差在20%以内,该方法具有一定的可行性。展开更多
发展耦合辐射的三维热化学非平衡流场计算方法,可用于非结构网格.采用Jameson有限体积法求解耦合辐射源项的三维N-S方程.辐射源项通过求解辐射输运方程(Radiative Transport Equation RTE)获得.在空间方向上离散后,采用有限体积法求解...发展耦合辐射的三维热化学非平衡流场计算方法,可用于非结构网格.采用Jameson有限体积法求解耦合辐射源项的三维N-S方程.辐射源项通过求解辐射输运方程(Radiative Transport Equation RTE)获得.在空间方向上离散后,采用有限体积法求解辐射输运方程.化学模型包含11个组元,20个化学反应.采用该数值方法计算MUSES-C模型在速度为11.6 km.s-1时的绕流流场及前驻点处的辐射热流密度.并通过对比,分析热辐射对流场的影响.展开更多
针对三维热化学非平衡辐射流场设计了基于非结构网格的数值计算方法.根据原子分子光谱理论逐条计算了100～1 500nm间N,O,N^+,O^+的谱线以及N_2,O_2,NO,N_2^+等分子的10个谱带,特别分析了NO的β′带,γ′带,δ带和ε带的辐射特性.采用耦...针对三维热化学非平衡辐射流场设计了基于非结构网格的数值计算方法.根据原子分子光谱理论逐条计算了100～1 500nm间N,O,N^+,O^+的谱线以及N_2,O_2,NO,N_2^+等分子的10个谱带,特别分析了NO的β′带,γ′带,δ带和ε带的辐射特性.采用耦合辐射的双温模型计算热化学非平衡流场,辐射源项通过直接求解辐射输运方程RTE(radiative transport equation)获得.在空间和方向上分别离散后,利用有限体积法求解不同方向上的辐射输运方程.计算得出了再入飞行器前驻点的辐射强度分布.采用该数值方法计算了MUSES—C模型在速度为11.6km/s时的绕流流场及前驻点处的辐射热流密度.并通过对比分析了热辐射对流场的影响.展开更多
When the frigate moves forward,due to the ship motion such as pitching and rolling,the flow over the flight deck becomes very complex,which may seriously threaten the taking off and landing of the ship-borne helicopte...When the frigate moves forward,due to the ship motion such as pitching and rolling,the flow over the flight deck becomes very complex,which may seriously threaten the taking off and landing of the ship-borne helicopter.The flow fields over the different modified simple frigate shape(SFS)models,consisting of the hangar and flight deck,were numerically studied by changing the ratio of hangar height and length in the static state and pitching state.For different models,the contours of velocity and pressure above the flight deck,as well as the variations of velocity components of the observation points and line in static state and pitching state were compared and analyzed.The results show that the size of recirculation zone and the location of the reattachment point have distinct differences for diverse models,and reveal the tracks of recirculation zone’s center and reattachment position in a pitching period.In addition,the velocity components at two observation positions also change periodically with the periodic motion.Furthermore,the deviations of the velocity components in static state and pitching state are relatively large,therefore,the flow fields in static state cannot be used to simulate that in pitching state correctly.展开更多
A numerical method is developed based on an unstructured mesh to compute an ionized hypersonic flowfield with radiation in the thermo-chemical nonequilibrium. The flowfield is described by multi-species NavierStocks e...A numerical method is developed based on an unstructured mesh to compute an ionized hypersonic flowfield with radiation in the thermo-chemical nonequilibrium. The flowfield is described by multi-species NavierStocks equations. The chemical model includes 11 species （O2, N2, O, N, NO, NO^＋ , N^＋ , O^＋, N2^＋ , O2^＋, e^- ） and 20 reactions. For simulating the thermal non-equilibrium effect, the two-temperature model is considered. The finite volume method （FVM） used for the spatial and directional discretization of radiative transfer equation（RTE） is described for unstructured grids. The numerical code can handle different kinds of species and radiative bands in a gas thermodynamicly described by two temperatures. In particular, the Delta, Epsilon, Beta prime, and Gamma prime bands of NO are choosen and the distribution of the radiation intensity is obtained.展开更多
文摘水滴平均体积直径(Mean volumetric diameter,MVD)和液态水含量(Liquid water content,LWC)是两个影响飞机结冰的重要气象参数,但在实际中难以准确测得,如果能够实时、准确地获取这两个参数可以为积冰预测和飞机适航认证标准的建立提供一些指导。文中提出了一种基于遗传算法优化神经网络的结冰气象参数预测模型。以不同测点组合的冰厚和结冰速率、环境温度、飞行速度和机翼迎角为输入参数,结冰气象参数MVD和LWC为输出参数,构建遗传算法优化的结冰气象参数预测模型,并通过预测模型对数值计算测试组数据和结冰风洞实验数据的结冰气象参数进行预测。结果表明,基于遗传算法优化Elman神经网络的预测模型对结冰气象参数的测试组预测相对误差在10%以内,实验数据相对误差在20%以内,该方法具有一定的可行性。
文摘发展耦合辐射的三维热化学非平衡流场计算方法,可用于非结构网格.采用Jameson有限体积法求解耦合辐射源项的三维N-S方程.辐射源项通过求解辐射输运方程(Radiative Transport Equation RTE)获得.在空间方向上离散后,采用有限体积法求解辐射输运方程.化学模型包含11个组元,20个化学反应.采用该数值方法计算MUSES-C模型在速度为11.6 km.s-1时的绕流流场及前驻点处的辐射热流密度.并通过对比,分析热辐射对流场的影响.
文摘针对三维热化学非平衡辐射流场设计了基于非结构网格的数值计算方法.根据原子分子光谱理论逐条计算了100～1 500nm间N,O,N^+,O^+的谱线以及N_2,O_2,NO,N_2^+等分子的10个谱带,特别分析了NO的β′带,γ′带,δ带和ε带的辐射特性.采用耦合辐射的双温模型计算热化学非平衡流场,辐射源项通过直接求解辐射输运方程RTE(radiative transport equation)获得.在空间和方向上分别离散后,利用有限体积法求解不同方向上的辐射输运方程.计算得出了再入飞行器前驻点的辐射强度分布.采用该数值方法计算了MUSES—C模型在速度为11.6km/s时的绕流流场及前驻点处的辐射热流密度.并通过对比分析了热辐射对流场的影响.
基金supported by the Fundamental Research Funds for the Central Universities(No. NS2019006)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘When the frigate moves forward,due to the ship motion such as pitching and rolling,the flow over the flight deck becomes very complex,which may seriously threaten the taking off and landing of the ship-borne helicopter.The flow fields over the different modified simple frigate shape(SFS)models,consisting of the hangar and flight deck,were numerically studied by changing the ratio of hangar height and length in the static state and pitching state.For different models,the contours of velocity and pressure above the flight deck,as well as the variations of velocity components of the observation points and line in static state and pitching state were compared and analyzed.The results show that the size of recirculation zone and the location of the reattachment point have distinct differences for diverse models,and reveal the tracks of recirculation zone’s center and reattachment position in a pitching period.In addition,the velocity components at two observation positions also change periodically with the periodic motion.Furthermore,the deviations of the velocity components in static state and pitching state are relatively large,therefore,the flow fields in static state cannot be used to simulate that in pitching state correctly.
文摘A numerical method is developed based on an unstructured mesh to compute an ionized hypersonic flowfield with radiation in the thermo-chemical nonequilibrium. The flowfield is described by multi-species NavierStocks equations. The chemical model includes 11 species （O2, N2, O, N, NO, NO^＋ , N^＋ , O^＋, N2^＋ , O2^＋, e^- ） and 20 reactions. For simulating the thermal non-equilibrium effect, the two-temperature model is considered. The finite volume method （FVM） used for the spatial and directional discretization of radiative transfer equation（RTE） is described for unstructured grids. The numerical code can handle different kinds of species and radiative bands in a gas thermodynamicly described by two temperatures. In particular, the Delta, Epsilon, Beta prime, and Gamma prime bands of NO are choosen and the distribution of the radiation intensity is obtained.
