Analysis of uncertainty factors in the prediction of missile pitch damping derivatives by unstructured CFD solver

Abstract

Based on the transient planar pitching method, the dynamic derivative calculation function is implemented on an unstructured computational fluid (CFD) software NNW-FlowStar. Then the pitch-damping dynamic derivatives of the standard model of the ANF missile at zero angles of attack and different Mach numbers (0.5∼4.5) are calculated. The influence of various numerical and physical parameters on the calculation results of dynamic derivatives is studied in detail. It is found that the dynamic derivatives of pitch damping are independent of the values of amplitude (0.125° ≤ A ≤ 1°) and reduction frequency (0.025 ≤ k ≤ 0.2). When the number of calculation steps of the sine oscillation period is 200 and the number of inner iterations is 40, the prediction accuracy and computing efficiency can meet the engineering requirements simultaneously in this case. The influence of different grid resolutions on the dynamic derivative calculation results is studied. Results show that the grid requirements of dynamic derivative calculation are consistent with those of steady-state calculations. Finally, the calculation results are compared with the free flight test results, which verifies the reliability of the methods and parameters suggested in this paper.