Based on computational fluid dynamics （CFD）/computational eleetromagnetics method （CEM） coupling method and surrogate model optimization techniques, an integration design method about aerodynamic/stealth character...Based on computational fluid dynamics （CFD）/computational eleetromagnetics method （CEM） coupling method and surrogate model optimization techniques, an integration design method about aerodynamic/stealth characteristics of airfoil is established. The O-type body-fitted and orthogonal grid around airfoil is first generated by using the Poisson equations, in which the points per wave and the normal range satisfy the aerodynamic and electromagnetic calculation accuracy requirement. Then the aerodynamic performance of airfoil is calculated by sol- ving the Navier-Stokes （N-S） equations with Baldwin-Lomax （B-L） turbulence model. The stealth characteristics of airfoil are simulated by using finite volume time domain （FVTD） method based on the Maxwell＇s equations, Steger-Warming flux splitting and the third-order MUSCL scheme. In addition, based upon the surrogate model optimization technique with full factorial design （FFD） and radial basis function （RBF）, an integration design about aerodynamic/stealth characteristics of rotor airfoil is conducted by employing the CFD/CEM coupling meth- od. The aerodynamic/stealth characteristics of NACA series airfoils with different maximum thickness and camber combinations are discussed. Finally, by choosing suitable lift-to-drag ratio and radar cross section （RCS） ampli- tudes of rotor airfoil in four important scattering regions as the objective function and constraint, the compromised airfoil with high lift-to-drag ratio and low scattering characteristics is designed via systemic and comprehensive ana- lyses.展开更多
The technology of pantograph sinking in the cavity is generally adopted in the new generation of high-speed trains in China for aerodynamic noise reduction in this region. This study takes a high-speed train with a 4-...The technology of pantograph sinking in the cavity is generally adopted in the new generation of high-speed trains in China for aerodynamic noise reduction in this region. This study takes a high-speed train with a 4-car formation and a pantograph as the research object and compares the aerodynamic acoustic performance of two scale models, 1/8 and 1/1, using large eddy simulation and Ffowcs Williams–Hawkings integral equation. It is found that there is no direct scale similarity between their aeroacoustic performance. The 1/1 model airflow is separated at the leading edge of the panhead and reattached to the panhead, and its vortex shedding Strouhal number(St) is 0.17. However, the 1/8 model airflow is separated directly at the leading edge of the panhead, and its St is 0.13. The cavity's vortex shedding frequency is in agreement with that calculated by the Rooster empirical formula. The two scale models exhibit some similar characteristics in distribution of sound source energy, but the energy distribution of the 1/8 model is more concentrated in the middle and lower regions. The contribution rates of their middle and lower regions to the radiated noise in the two models are 27.3% and 87.2%, respectively. The peak frequencies of the radiated noise from the 1/1 model are 307 and 571 Hz. The 307 Hz is consistent with the frequency of panhead vortex shedding, and the 571 Hz is more likely to be the result of the superposition of various components. In contrast, the peak frequencies of the radiated noise from the 1/8 scale model are 280 and 1970 Hz. The 280 Hz comes from the shear layer oscillation between the cavity and the bottom frame, and the 1970 Hz is close to the frequency at which the panhead vortex sheds. This shows that the scaled model results need to be corrected before applying to the full-scale model.展开更多
Several types of coupling methods for resolving aerothermoelastic problems associated with hypersonic wings are summarized,and the appropriate coupling methods for engineering calculations are selected.Then,the calcul...Several types of coupling methods for resolving aerothermoelastic problems associated with hypersonic wings are summarized,and the appropriate coupling methods for engineering calculations are selected.Then,the calculation and analysis methods for the subdisciplines in this field are introduced,and the time step issue is discussed.A two-way-coupling rapid static aerothermoelastic method for analyzing hypersonic wings is proposed.This method considers thermal effects and is used to conduct an aerothermoelastic response analysis for a hypersonic wing.In addition,the aerodynamic force,heat flux,structural deformation and temperature field are obtained.The following three conclusions are drawn.First,the heating effect has a significant impact on the static aeroelastic response of hypersonic wings;therefore,thermal protection shields are essential.Second,the application of thermal protection shields reduces the differences in the calculation results between the one-and two-way-coupling methods.Third,hypersonic wings exhibit large thermal deformation under high-temperature environments,and in certain cases,the thermal deformation is even larger than the deformation caused by aerodynamic force.展开更多
The coupling behavior of the imbedded weapon store occurring between the local unsteady flow field round the store and the structure response on the processing of opening its bay-door is simulated by using numerical m...The coupling behavior of the imbedded weapon store occurring between the local unsteady flow field round the store and the structure response on the processing of opening its bay-door is simulated by using numerical method based on computational fluid mechanics(CFD).The transient aerodynamic behaviors when opening door under various flight altitudes and the corresponding structure deformation evolution in the unsteady flow fields are analyzed respectively and presented.The rules of aircraft attitude parameters′impacting to the responses of structure and the bay-door′s opening process are obtained by comparing with the analysis results.These rules can be applied to the structure design of bay-door and route specification of missile when disengaged and launched from within store.展开更多
文摘Based on computational fluid dynamics （CFD）/computational eleetromagnetics method （CEM） coupling method and surrogate model optimization techniques, an integration design method about aerodynamic/stealth characteristics of airfoil is established. The O-type body-fitted and orthogonal grid around airfoil is first generated by using the Poisson equations, in which the points per wave and the normal range satisfy the aerodynamic and electromagnetic calculation accuracy requirement. Then the aerodynamic performance of airfoil is calculated by sol- ving the Navier-Stokes （N-S） equations with Baldwin-Lomax （B-L） turbulence model. The stealth characteristics of airfoil are simulated by using finite volume time domain （FVTD） method based on the Maxwell＇s equations, Steger-Warming flux splitting and the third-order MUSCL scheme. In addition, based upon the surrogate model optimization technique with full factorial design （FFD） and radial basis function （RBF）, an integration design about aerodynamic/stealth characteristics of rotor airfoil is conducted by employing the CFD/CEM coupling meth- od. The aerodynamic/stealth characteristics of NACA series airfoils with different maximum thickness and camber combinations are discussed. Finally, by choosing suitable lift-to-drag ratio and radar cross section （RCS） ampli- tudes of rotor airfoil in four important scattering regions as the objective function and constraint, the compromised airfoil with high lift-to-drag ratio and low scattering characteristics is designed via systemic and comprehensive ana- lyses.
基金supported by the National Natural Science Foundation of China (No. 52272363)the Key Laboratory of Aerodynamic Noise Control (No. ANCL20200302),Aid Program for Science and Technology Innovative Research Team in Higher Educational Institutions of Hunan Province。
文摘The technology of pantograph sinking in the cavity is generally adopted in the new generation of high-speed trains in China for aerodynamic noise reduction in this region. This study takes a high-speed train with a 4-car formation and a pantograph as the research object and compares the aerodynamic acoustic performance of two scale models, 1/8 and 1/1, using large eddy simulation and Ffowcs Williams–Hawkings integral equation. It is found that there is no direct scale similarity between their aeroacoustic performance. The 1/1 model airflow is separated at the leading edge of the panhead and reattached to the panhead, and its vortex shedding Strouhal number(St) is 0.17. However, the 1/8 model airflow is separated directly at the leading edge of the panhead, and its St is 0.13. The cavity's vortex shedding frequency is in agreement with that calculated by the Rooster empirical formula. The two scale models exhibit some similar characteristics in distribution of sound source energy, but the energy distribution of the 1/8 model is more concentrated in the middle and lower regions. The contribution rates of their middle and lower regions to the radiated noise in the two models are 27.3% and 87.2%, respectively. The peak frequencies of the radiated noise from the 1/1 model are 307 and 571 Hz. The 307 Hz is consistent with the frequency of panhead vortex shedding, and the 571 Hz is more likely to be the result of the superposition of various components. In contrast, the peak frequencies of the radiated noise from the 1/8 scale model are 280 and 1970 Hz. The 280 Hz comes from the shear layer oscillation between the cavity and the bottom frame, and the 1970 Hz is close to the frequency at which the panhead vortex sheds. This shows that the scaled model results need to be corrected before applying to the full-scale model.
基金supported partly by the National Natural Science Foundation of China (Nos.11302011, 11402013,11372023,11672018)the National Key Research and Development Program (No.2016YFB0200703)the Fundamental Research Funds for the Central Universities(No.YWF-14-HKXY-006)
文摘Several types of coupling methods for resolving aerothermoelastic problems associated with hypersonic wings are summarized,and the appropriate coupling methods for engineering calculations are selected.Then,the calculation and analysis methods for the subdisciplines in this field are introduced,and the time step issue is discussed.A two-way-coupling rapid static aerothermoelastic method for analyzing hypersonic wings is proposed.This method considers thermal effects and is used to conduct an aerothermoelastic response analysis for a hypersonic wing.In addition,the aerodynamic force,heat flux,structural deformation and temperature field are obtained.The following three conclusions are drawn.First,the heating effect has a significant impact on the static aeroelastic response of hypersonic wings;therefore,thermal protection shields are essential.Second,the application of thermal protection shields reduces the differences in the calculation results between the one-and two-way-coupling methods.Third,hypersonic wings exhibit large thermal deformation under high-temperature environments,and in certain cases,the thermal deformation is even larger than the deformation caused by aerodynamic force.
文摘The coupling behavior of the imbedded weapon store occurring between the local unsteady flow field round the store and the structure response on the processing of opening its bay-door is simulated by using numerical method based on computational fluid mechanics(CFD).The transient aerodynamic behaviors when opening door under various flight altitudes and the corresponding structure deformation evolution in the unsteady flow fields are analyzed respectively and presented.The rules of aircraft attitude parameters′impacting to the responses of structure and the bay-door′s opening process are obtained by comparing with the analysis results.These rules can be applied to the structure design of bay-door and route specification of missile when disengaged and launched from within store.
