The simulation techniques of hardware-in-loop simulation(HLS) of homing antitank missile based on the personal computer (PC) are discussed. The PC and MCS-96 chip controller employ A/D and D/A boards (with photoelectr...The simulation techniques of hardware-in-loop simulation(HLS) of homing antitank missile based on the personal computer (PC) are discussed. The PC and MCS-96 chip controller employ A/D and D/A boards (with photoelectricity isolation) to transfer measur ment and control information about homing head, gyro and rudder and utilize the digital hand shaking board to build correct communication communication protocol. In order to satisfy the real-time requirement of HLS, this paper first simplifies the aerodynamic data file reasonably, then builds a PC software with C language. The program of the controller part is made with PL/M language. The simulation of HLS based on PC is done with the same sampling period of 10ms as that of YH-F1 and the experiment results are identical to those of digital simulation of the homing anti-tank guided missile.展开更多
For the accurate description of aerodynamic characteristics for aircraft,a wavelet neural network (WNN) aerodynamic modeling method from flight data,based on improved particle swarm optimization (PSO) algorithm with i...For the accurate description of aerodynamic characteristics for aircraft,a wavelet neural network (WNN) aerodynamic modeling method from flight data,based on improved particle swarm optimization (PSO) algorithm with information sharing strategy and velocity disturbance operator,is proposed.In improved PSO algorithm,an information sharing strategy is used to avoid the premature convergence as much as possible;the velocity disturbance operator is adopted to jump out of this position once falling into the premature convergence.Simulations on lateral and longitudinal aerodynamic modeling for ATTAS (advanced technologies testing aircraft system) indicate that the proposed method can achieve the accuracy improvement of an order of magnitude compared with SPSO-WNN,and can converge to a satisfactory precision by only 60 120 iterations in contrast to SPSO-WNN with 6 times precocities in 200 times repetitive experiments using Morlet and Mexican hat wavelet functions.Furthermore,it is proved that the proposed method is feasible and effective for aerodynamic modeling from flight data.展开更多
The accuracy of a flight simulation is highly dependent on the quality of the aerodynamic database and prediction accuracies of the aerodynamic coefficients and derivatives. A surrogate model is an approximation metho...The accuracy of a flight simulation is highly dependent on the quality of the aerodynamic database and prediction accuracies of the aerodynamic coefficients and derivatives. A surrogate model is an approximation method that is used to predict unknown functions based on the sampling data obtained by the design of experiments. This model can also be used to predict aerodynamic coefficients/derivatives using several measured points. The objective of this paper is to develop an efficient digital flight simulation by solving the equation of motion to predict the aerodynamics data using a surrogate model. Accordingly, there is a need to construct and investigate aerodynamic databases and compare the accuracy of the surrogate model with the exact solution, and hence solve the equation of motion for the flight simulation analysis. In this study, sample datas for models are acquired from the USAF Stability and Control DATCOM, and a database is constructed for two input variables （the angle of attack and Mach number）, along with two derivatives of the X-force axis and three derivatives for the Z-force axis and pitching moment. Furthermore, a comparison of the value predicted by the Kriging model and the exact solution shows that its flight analysis prediction ability makes it possible to use the surrogate model in future analyses.展开更多
One of the key features of Laplace＇s Equation is the property that allows the equation governing the flow field to be converted from a 3D problem throughout the field to a 2D problem for finding the potential on the ...One of the key features of Laplace＇s Equation is the property that allows the equation governing the flow field to be converted from a 3D problem throughout the field to a 2D problem for finding the potential on the surface. The solution is then found using this property by distributing ＂singularities＂ of unknown strength over discretized portions of the surface： panels. Hence the flow field solution is found by representing the surface by a number of panels, and solving a linear set of algebraic equations to determine the unknown strengths of the singularities. In this paper a Hess-Smith Panel Method is then used to examine the aerodynamics of NACA 4412 and NACA 23015 wind turbine airfoils. The lift coefficient and the pressure distribution are predicted and compared with experimental result for low Reynolds number. Results show a good agreement with experimental data.展开更多
Off-statistics input data sets are common in axial-flow fans design and may easily result in some violation of the requirements of a good aerodynamic blade design.In order to circumvent this problem,in the present pap...Off-statistics input data sets are common in axial-flow fans design and may easily result in some violation of the requirements of a good aerodynamic blade design.In order to circumvent this problem,in the present paper,a solution to the radial equilibrium equation is found which minimizes the outlet kinetic energy and fulfills the aerodynamic constraints,thus ensuring that the resulting blade has acceptable aerodynamic performance.The presented method is based on the optimization of a three-parameters vortex law and of the meridional channel size.The aerodynamic quantities to be employed as constraints are individuated and their suitable ranges of variation are proposed.The method is validated by means of a design with critical input data values and CFD analysis.Then,by means of systematic computations with different input data sets,some correlations and charts are obtained which are analogous to classic correlations based on statistical investigations on existing machines.Such new correlations help size a fan of given characteristics as well as study the feasibility of a given design.展开更多
文摘The simulation techniques of hardware-in-loop simulation(HLS) of homing antitank missile based on the personal computer (PC) are discussed. The PC and MCS-96 chip controller employ A/D and D/A boards (with photoelectricity isolation) to transfer measur ment and control information about homing head, gyro and rudder and utilize the digital hand shaking board to build correct communication communication protocol. In order to satisfy the real-time requirement of HLS, this paper first simplifies the aerodynamic data file reasonably, then builds a PC software with C language. The program of the controller part is made with PL/M language. The simulation of HLS based on PC is done with the same sampling period of 10ms as that of YH-F1 and the experiment results are identical to those of digital simulation of the homing anti-tank guided missile.
文摘For the accurate description of aerodynamic characteristics for aircraft,a wavelet neural network (WNN) aerodynamic modeling method from flight data,based on improved particle swarm optimization (PSO) algorithm with information sharing strategy and velocity disturbance operator,is proposed.In improved PSO algorithm,an information sharing strategy is used to avoid the premature convergence as much as possible;the velocity disturbance operator is adopted to jump out of this position once falling into the premature convergence.Simulations on lateral and longitudinal aerodynamic modeling for ATTAS (advanced technologies testing aircraft system) indicate that the proposed method can achieve the accuracy improvement of an order of magnitude compared with SPSO-WNN,and can converge to a satisfactory precision by only 60 120 iterations in contrast to SPSO-WNN with 6 times precocities in 200 times repetitive experiments using Morlet and Mexican hat wavelet functions.Furthermore,it is proved that the proposed method is feasible and effective for aerodynamic modeling from flight data.
文摘The accuracy of a flight simulation is highly dependent on the quality of the aerodynamic database and prediction accuracies of the aerodynamic coefficients and derivatives. A surrogate model is an approximation method that is used to predict unknown functions based on the sampling data obtained by the design of experiments. This model can also be used to predict aerodynamic coefficients/derivatives using several measured points. The objective of this paper is to develop an efficient digital flight simulation by solving the equation of motion to predict the aerodynamics data using a surrogate model. Accordingly, there is a need to construct and investigate aerodynamic databases and compare the accuracy of the surrogate model with the exact solution, and hence solve the equation of motion for the flight simulation analysis. In this study, sample datas for models are acquired from the USAF Stability and Control DATCOM, and a database is constructed for two input variables （the angle of attack and Mach number）, along with two derivatives of the X-force axis and three derivatives for the Z-force axis and pitching moment. Furthermore, a comparison of the value predicted by the Kriging model and the exact solution shows that its flight analysis prediction ability makes it possible to use the surrogate model in future analyses.
文摘One of the key features of Laplace＇s Equation is the property that allows the equation governing the flow field to be converted from a 3D problem throughout the field to a 2D problem for finding the potential on the surface. The solution is then found using this property by distributing ＂singularities＂ of unknown strength over discretized portions of the surface： panels. Hence the flow field solution is found by representing the surface by a number of panels, and solving a linear set of algebraic equations to determine the unknown strengths of the singularities. In this paper a Hess-Smith Panel Method is then used to examine the aerodynamics of NACA 4412 and NACA 23015 wind turbine airfoils. The lift coefficient and the pressure distribution are predicted and compared with experimental result for low Reynolds number. Results show a good agreement with experimental data.
文摘Off-statistics input data sets are common in axial-flow fans design and may easily result in some violation of the requirements of a good aerodynamic blade design.In order to circumvent this problem,in the present paper,a solution to the radial equilibrium equation is found which minimizes the outlet kinetic energy and fulfills the aerodynamic constraints,thus ensuring that the resulting blade has acceptable aerodynamic performance.The presented method is based on the optimization of a three-parameters vortex law and of the meridional channel size.The aerodynamic quantities to be employed as constraints are individuated and their suitable ranges of variation are proposed.The method is validated by means of a design with critical input data values and CFD analysis.Then,by means of systematic computations with different input data sets,some correlations and charts are obtained which are analogous to classic correlations based on statistical investigations on existing machines.Such new correlations help size a fan of given characteristics as well as study the feasibility of a given design.
