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Periodic unsteady flow field prediction method suitable for CFD numerical simulation

A technology of unsteady flow field and prediction method, which is applied in the prediction field of periodic unsteady flow field suitable for CFD numerical simulation. problem, to achieve the effect of improving computing efficiency, good inheritance, and computing efficiency.

Inactive Publication Date: 2016-07-27
CHINA ACAD OF AEROSPACE AERODYNAMICS
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Problems solved by technology

At present, this kind of unsteady flow is usually numerically simulated by the dual-time-step method, but the dual-time-step method does not consider the periodic characteristics of the flow, so the calculation efficiency is not high, especially for the hypersonic flow due to the sharp reduction of the characteristic time, the calculation cost will be more high
In order to reduce the amount of calculation, some scholars have proposed a series of simplified algorithms. However, the key to unsteady flow calculation is to achieve a good balance between calculation efficiency and calculation accuracy. High-precision and high-resolution methods are usually used by current computer systems. Computing power is limited, and low-precision algorithms usually cannot reflect some important physical information

Method used

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  • Periodic unsteady flow field prediction method suitable for CFD numerical simulation
  • Periodic unsteady flow field prediction method suitable for CFD numerical simulation
  • Periodic unsteady flow field prediction method suitable for CFD numerical simulation

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Embodiment

[0070] (1) The calculation model adopts NACA0015 airfoil, the chord length of the airfoil is c=0.3048m, and the calculation grid is generated within the range of ten times the chord length, that is, the calculation domain, as shown in figure 1 As shown, there are 260 points on the surface of the airfoil, and the grid spacing of the first layer of the wall is 3×10 -6 m, the NACA0015 airfoil performs sinusoidal pitch vibration, namely

[0071] α=4.0+4.2sin(20πt)

[0072] Among them, α is the attack angle of NACA0015 airfoil, and t is the vibration time;

[0073] (2) Divide a calculation cycle into 5 sampling points with equal time intervals, namely (0.00s, 0.02s, 0.04s, 0.06s, 0.08s), at this time, the D matrix is:

[0074] D = 0 53.45 - 33.03 33.03 ...

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Abstract

The invention relates to a periodic unsteady flow field prediction method suitable for CFD (computational fluid mechanics) numerical simulation. According to the method, Fourier transform is adopted to transform a time-dependent periodic unsteady problem in a time domain into N coupled steady equations, and the whole period can be reconstructed through coupling and computing N steady moments, so that the computing efficiency can be greatly improved under the condition of not reducing the computing accuracy. The method can be used for efficiently and accurately obtaining the periodic unsteady flow field distribution of aircrafts, obtaining the periodic unsteady aerodynamic force of the aircrafts according to the obtained flow field distribution and guiding the dynamic stability design of the aircrafts according to the obtained periodic unsteady aerodynamic force.

Description

technical field [0001] The present invention relates to a method for predicting periodic unsteady flow field suitable for CFD (computational fluid dynamics) numerical simulation. The periodic unsteady aerodynamic force of the aircraft is obtained, and then the dynamic stability design of the aircraft can be guided according to the obtained periodic unsteady aerodynamic force. Background technique [0002] Periodic unsteady flow has a wide range of engineering application backgrounds, such as the flow around the rotor of a helicopter, the internal flow of a turbine including a stator and rotor, the flow around a fan blade, and the study of flapping wing power devices. In addition, the numerical forced vibration method calculates the dynamic derivative and makes the object vibrate at a given frequency. The key is to obtain the hysteretic aerodynamic force directly related to the vibration frequency under the condition of periodic motion. All the above-mentioned flows have an ...

Claims

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Application Information

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IPC IPC(8): G06F19/00
CPCG16Z99/00
Inventor 谢立军杨云军刘周周伟江
Owner CHINA ACAD OF AEROSPACE AERODYNAMICS
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