Chu Tang

Bio: Chu Tang is an academic researcher from Aviation Industry Corporation of China. The author has contributed to research in topics: Downwash & Flutter. The author has an hindex of 1, co-authored 2 publications receiving 4 citations.

Whirl flutter analysis method of propeller-driven aircraft

Abstract: The invention relates to a whirl flutter analysis method of a propeller-driven aircraft. The whirl flutter analysis method comprises the following steps: 1) establishing a wing finite element model, and carrying out dynamic characteristic analysis; 2) calculating the dynamic characteristic of a nacelle/ propeller system; 3) calculating an unsteady aerodynamic force influence coefficient matrix among wing aerodynamic grids and the aerodynamic influence coefficient matrix, on the sidewash w and the downwash v of a propeller hub point, of the wing aerodynamic grid; 4) calculating the aerodynamic derivatives of the propeller under different flight states, and assembling an aerodynamic matrix; 5) on the basis of an installation relationship of the wing/ the nacelle/ the propeller, deducing the mathematical expression form of the effective pitch angle and yaw angle of the propeller; 6) obtaining an unsteady aerodynamic force matrix which is applied to a wing installation point by the propeller to obtain a whirl flutter kinematic equation; and 7) solving the whirl flutter kinematic equation, and analyzing whirl flutter characteristics. The whirl flutter analysis method of the propeller-driven aircraft has the advantages of being high in analysis accuracy, wide in application ranges and the like.

A New Whirl Flutter Analysis Method

Abstract: The aeroelastic instability of wing/nacelle/propeller must be carried out during the process of turboprop aircraft design and certification. The relation of wing and propeller/nacelle motions is derived and the generalized force acting between the wing and propeller/nacelle is computed by principle of virtual work. The effects of wing downwash and sidewash on propellers are also considered. The motion equations are set up by use of the FEM wing model and the two-degree proprotor/nacelle math model of Wilmer and a new whirl-flutter analysis method suitable for engineering applications is developed. By using the time domain and frequency domain methods, the whirl flutter stability characteristics of propeller/nacelle and wing/nacelle/wing systems can be predicted. Comparisons with the publishable articles indicate good agreement. The parametric analyses demonstrate the mounting stiffness of propeller/nacelle dominates whether the wing and the propeller/nacelle are coupled and the distributions of the main wing frequencies and propeller/nacelle frequencies determine the coupling relationship. Once coupling, the wing flutter instability is improved.

Unsteady aerodynamic force calculation method considering curved surface effect and normal motion of aerodynamic surface

Abstract: The invention provides an unsteady aerodynamic force calculation method considering the curved surface effect and normal motion of an aerodynamic surface. The method comprises the following steps: carrying out grid division on the deformed aerodynamic surface of an aircraft; acquiring a structural elastic mode of the aircraft; extracting a structural elastic mode related to the deformed pneumaticsurface and interpolating the structural elastic mode to a pneumatic grid; arranging a dipole basic solution on the grid, solving a kernel function, and solving an aerodynamic force influence coefficient matrix according to the kernel function; calculating a local normal vector of the pneumatic grid of the deformed pneumatic surface; solving a normal motion boundary condition according to the normal mode of the deformed pneumatic surface; solving the unsteady aerodynamic force on the deformed aerodynamic surface grid; and obtaining generalized curved surface unsteady aerodynamic force according to the unsteady aerodynamic force on the deformed pneumatic surface grid and the normal mode of the deformed pneumatic surface. By the application of the technical scheme, the technical problem thataccurate description and calculation of the flexible aircraft frequency domain unsteady aerodynamic force cannot be achieved in the prior art is solved.

Hartley modeling method for aircraft flutter analysis mesh model

Abstract: The invention provides a Hartley modeling method for an aircraft flutter analysis mesh model in order to overcome the problem that the prior art cannot effectively express a complex flutter model under the influence of aerodynamic force and intensity variation. The method selects multiple mesh points in an aircraft body shaft system, the complex flutter mesh model is expressed according to an aircraft body shaft system decomposition method under the influence of aerodynamic force and intensity variation such as different flight speed, atmospheric density, airflow environment, different temperature and the like, the requirements of sensor installation and data and image recording are proposed according to the requirements of establishment of the model, data is obtained by an effective flutter flight test, an excitation function is obtained through an airflow sensor measurement value, approximation and equivalent description of vibration variables is conducted by using the Hartley function, the solving of three axial vibration equations at the aircraft body shaft system coordinate mesh points is determined simultaneously according to an identification method, and the technical problem that the prior art cannot effectively express the complex flutter model under the influence of aerodynamic force and intensity variation is solved.

Thin-wall structure thermodynamic elastic dynamic response analysis method

Abstract: The invention provides a thin-wall structure thermodynamic elastic dynamic response analysis method, which comprises the following steps: according to a thin-wall structure and boundary conditions, dispersing the thin-wall structure into seven-degree-of-freedom shell units, dispersing ribs into seven-degree-of-freedom beam units, and establishing a thin-wall finite element model to obtain a structure finite element grid; applying a thin-wall structure temperature field to the structure finite element grid, performing linear flutter analysis on the finite element model to obtain an unsteady aerodynamic matrix Qk corresponding to each reduction frequency k, and fitting a time domain expression of the unsteady aerodynamic matrix; and carrying out iterative calculation on the obtained time domain expression of the unsteady aerodynamic matrix, and carrying out nonlinear transient response analysis on the thin wall to obtain the nonlinear thermodynamic elastic dynamic response of the thin wall structure. The method provided by the invention can solve the calculation problem of the nonlinear thermodynamic elastic dynamic response of a complex thin-wall structure.

Method for calculating aerodynamic characteristics of power cabin

Abstract: A method for calculating aerodynamic characteristics of a power cabin is suitable for calculation of aerodynamic characteristics of a helicopter power cabin and belongs to the field of helicopter power cabin design The method comprises the steps that 1, grid partition is conducted on a calculated zone, wherein the calculated zone is divided into at least three zones including a rotor wing sub-zone, a power cabin sub-zone and a far field sub-zone; 2, a calculation model is established; 3, a result is calculated, and a real power cabin inner flow field is obtained A downwash flow field is calculated by adopting a sliding mesh technology and has non-homogeneous characteristics, a chaos flow field at a rotor hub can be accurately caught to obtain an external flow field of a real power cabin In addition, expanding characteristics of high-temperature jet flow of an engine and calculation of radiant heat dissipation characteristics of the outer surface of an engine are further considered, so that the power cabin inner flow field is real Calculation of the aerodynamic characteristics of the helicopter power cabin is more accurate by mutually coupling internal and external flow fields of the power cabin