A more accurate method for calculating transonic dynamic derivatives (TDDs) using present state-of-the-art CFD

Aim: Predicting the TDDs requires a new unsteady aerodynamics calculation method. In this regard, computational fluid dynamics (CFD) can help to study the aerodynamic characteristics of an aircraft. In the full paper, we explain in some detail the method for calculating the TDDs of 3-D unsteady transonic flow around the aircraft; in this abstract, we just add some pertinent remarks to listing the two topics of explanation. The first topic is: The solver of the Euler equations. In this topic, we apply the unstructured dynamic mesh technique to calculating the flow around the aircraft and make some improvements. The second topic is: The method for calculating TDDs using the present state-of-the-art CFD. Its two subtopics are: The expressions of unsteady aerodynamic moments (subtopic 2.1) and the derivation of the equations for the TDDs (subtopic 2.2). In the subtopic 2.1, we use eqs. (3) and (4) to express the unsteady aerodynamic moments of the aircraft with low-frequency small-amplitude pitch oscillations. In subtopic 2.2, we explain how to use the present state-of-the-art CFD to calculate the unsteady aerodynamic moment when it reaches stable cyclic variation and then we use eq. (8) to calculate the longitudinal combinatory derivatives of the aircraft. Finally, to verify the present method, we, like others, take the Basic Finner missile as the benchmark example to calculate its longitudinal combinatory derivatives and simulate the unsteady transonic flow around the missile. The simulation results, shown in Figs. 3 and 4 in the full paper, indicate preliminarily that the calculations results, given in Fig. 5, are in fairly good agreement with the tunnel experimental results in Ref. 7 by R. E. Bolz et al and are more accurate than the published calculation results available abroad.