Performance Analysis Of Continuous Descent Operation Based On 4D Trajectory

The Continuous Descent Operation(CDO)is a terminal area approach trajectory management technology promoted by the Civil Aviation Administration of China.This technology is based on its high down trajectory and the ideal thrust descent.Compared with the traditional approach method,it can effectively reduce the time consumption,noise pollution and fuel consumption of the aircraft in the terminal area.Under the current situation,the aircraft uses the standard approach route for approaching,so the optimization of the track for the vertical profile is very important,and the performance indicators of the shortest time and the most fuel-saving are gradually appearing in the optimized management of the descending track profile.Firstly,based on the performance of the aircraft,different descending modes are combined to form different CDO trajectory profiles.Based on the division of CDO trajjectory,combined with the relevant BADA performance model parameters,the corresponding descending CDO trajectory are calculated and generated.In the case of giving relevant route point information and constraints,the CDO trajectory of B737-800 is simulated and predicted,and finally the prediction result is compared with the traditional step down trajectory.Secondly,the method of using the indirect method to optimize the CDO trajectory is analyzed,and the traditional trajectory differential equations are simplified,so that the optimal control variable of the optimal solution can be obtained quickly.The optimized trajectory of the optimized condition can be effectively obtained by dividing the descending gradient.Compared with the previously generated VNAV CDO model,the model has certain optimization performance,but the conclusion proves that the method is cumbersome and complicated in operation.Then the direct method is used to optimize the trajectory,and the difference between the three pseudo-spectral methods is analyzed.Then the Gauss pseudo-spectral method is used to optimize the CDO vertical profile trajectory,and the minimum time CDO trajectory and minimum fuel CDO trajectory are optimized by matlab GPOPS toolbox simulation analysis.The CDO trajectory shows that optimizing the CDO operation mode has a big advantage in saving time and saving fuel.And the optimization performance of three different pseudo-spectral methods is analyzed,and the accuracy of the pseudo-spectral method on the shortest time and the most fuel-saving problem on the optimization problem is compared and analyzed.Finally,based on the optimization model of Gauss pseudospectral method,Newton interpolation is used to replace Lagrange interpolation,and the calculation of high-order differential matrix is avoided.The simulation results show that Gaussian pseudo-spectral method can achieve faster operation efficiency by adopting Newton interpolation.The Gauss pseudo-spectral method is improved by replacing the Gauss points with Chebyshev-Gauss points.The results show that the improved Chebyshev-Gauss pseudo-spectral method has better optimization accuracy when the same number of points is adopted.