In view of engineering application, it is practicable to decompose the aerodynamics into three components： the static aerodynamics, the aerodynamic increment due to steady rotations, and the aerodynamic increment due...In view of engineering application, it is practicable to decompose the aerodynamics into three components： the static aerodynamics, the aerodynamic increment due to steady rotations, and the aerodynamic increment due to unsteady separated and vortical flow. The first and the second components can be presented in conventional forms, while the third is described using a one-order differential equation and a radial-basis-function （RBF） network. For an aircraft configuration, the mathematical models of 6- component aerodynamic coefficients are set up from the wind tunnel test data of pitch, yaw, roll, and coupled yawroll large-amplitude oscillations. The flight dynamics of an aircraft is studied by the bifurcation analysis technique in the case of quasi-steady aerodynamics and unsteady aerodynam- ics, respectively. The results show that： （1） unsteady aerodynamics has no effect upon the existence of trim points, but affects their stability; （2） unsteady aerodynamics has great effects upon the existence, stability, and amplitudes of periodic solutions; and （3） unsteady aerodynamics changes the stable regions of trim points obviously. Furthermore, the dynamic responses of the aircraft to elevator deflections are inspected. It is shown that the unsteady aerodynamics is beneficial to dynamic stability for the present aircraft. Finally, the effects of unsteady aerodynamics on the post-stall maneuverability展开更多
A structure-based modeling of the CaO-‘FeO’-MgO-Al_(2)O_(3)-SiO_(2) system and its subsystems was investigated based on iron extraction nickel slagaluminum dross.Parameters optimization in the present model indicate...A structure-based modeling of the CaO-‘FeO’-MgO-Al_(2)O_(3)-SiO_(2) system and its subsystems was investigated based on iron extraction nickel slagaluminum dross.Parameters optimization in the present model indicated that the coefficient of free O^(2-)in FeO,a_(O_(FeO)^(2-)),on the lengths of network linkage had the largest value and O_(FeO)^(2-)(free O^(2)-in FeO)had the largest mobility.The coefficients of bridging oxygen(a_(Si-O-Al) and a_(Al-O-Al))were lower than those of nonbridging oxygen and free oxygen(O^(2-)).Viscosity prediction for the CaO-‘FeO’-(8 wt.%)MgO-Al_(2)O_(3)-SiO_(2) system was conducted at a fixed slag basicity,which indicated that the predicted viscosity changed monotonously with the FeO content.However,the non-monotonous evolution with Al2O3 content reflected the amphoteric behavior of Al2O3.In addition,the performances of the present model in predicting viscosity binary(‘FeO’-SiO_(2))to quinary(CaO-‘FeO’-MgO-Al_(2)O_(3)-SiO_(2))system were analyzed and a comparison with the established models was made.展开更多
文摘In view of engineering application, it is practicable to decompose the aerodynamics into three components： the static aerodynamics, the aerodynamic increment due to steady rotations, and the aerodynamic increment due to unsteady separated and vortical flow. The first and the second components can be presented in conventional forms, while the third is described using a one-order differential equation and a radial-basis-function （RBF） network. For an aircraft configuration, the mathematical models of 6- component aerodynamic coefficients are set up from the wind tunnel test data of pitch, yaw, roll, and coupled yawroll large-amplitude oscillations. The flight dynamics of an aircraft is studied by the bifurcation analysis technique in the case of quasi-steady aerodynamics and unsteady aerodynam- ics, respectively. The results show that： （1） unsteady aerodynamics has no effect upon the existence of trim points, but affects their stability; （2） unsteady aerodynamics has great effects upon the existence, stability, and amplitudes of periodic solutions; and （3） unsteady aerodynamics changes the stable regions of trim points obviously. Furthermore, the dynamic responses of the aircraft to elevator deflections are inspected. It is shown that the unsteady aerodynamics is beneficial to dynamic stability for the present aircraft. Finally, the effects of unsteady aerodynamics on the post-stall maneuverability
基金supported by the National Natural Science Foundation of China(Grant Nos.51774072,5207040904,51774073 and 51974080)the National Key R&D Program of China(Grant Nos.2017YFB0304201 and 2017YFB0304203).
文摘A structure-based modeling of the CaO-‘FeO’-MgO-Al_(2)O_(3)-SiO_(2) system and its subsystems was investigated based on iron extraction nickel slagaluminum dross.Parameters optimization in the present model indicated that the coefficient of free O^(2-)in FeO,a_(O_(FeO)^(2-)),on the lengths of network linkage had the largest value and O_(FeO)^(2-)(free O^(2)-in FeO)had the largest mobility.The coefficients of bridging oxygen(a_(Si-O-Al) and a_(Al-O-Al))were lower than those of nonbridging oxygen and free oxygen(O^(2-)).Viscosity prediction for the CaO-‘FeO’-(8 wt.%)MgO-Al_(2)O_(3)-SiO_(2) system was conducted at a fixed slag basicity,which indicated that the predicted viscosity changed monotonously with the FeO content.However,the non-monotonous evolution with Al2O3 content reflected the amphoteric behavior of Al2O3.In addition,the performances of the present model in predicting viscosity binary(‘FeO’-SiO_(2))to quinary(CaO-‘FeO’-MgO-Al_(2)O_(3)-SiO_(2))system were analyzed and a comparison with the established models was made.
