This paper revisits the Space-Time Gradient(STG)method which was developed for effi-cient analysis of unsteady flows due to rotor-stator interaction and presents the method from an alternative time-clocking perspective.The STG method requires reordering of blade passages according to their relative clocking positions with respect to blades of an adjacent blade row.As the space-clocking is linked to an equivalent time-clocking,the passage reordering can be performed according to the alternative time-clocking.With the time-clocking perspective,unsteady flow solu-tions from different passages of the same blade row are mapped to flow solutions of the same pas-sage at different time instants or phase angles.Accordingly,the time derivative of the unsteady flow equation is discretized in time directly,which is more natural than transforming the time derivative to a spatial one as with the original STG method.To improve the solution accuracy,a ninth order difference scheme has been investigated for discretizing the time derivative.To achieve a stable solu-tion for the high order scheme,the implicit solution method of Lower-Upper Symmetric Gauss-Seidel/Gauss-Seidel(LU-SGS/GS)has been employed.The NASA Stage 35 and its blade-count-reduced variant are used to demonstrate the validity of the time-clocking based passage reordering and the advantages of the high order difference scheme for the STG method.Results from an exist-ing harmonic balance flow solver are also provided to contrast the two methods in terms of solution stability and computational cost.

Boqian WANG;Dingxi WANG;Mohammad RAHMATI;Xiuquan HUANG

School of Power and Energy,Northwestern Polytechnical University,Xi'an 710072,China;Department of Mechanical and Construction Engineering,Northumbria University,Newcastle upon Tyne NE1 8ST,United Kingdom

中国航空学报（英文版）

[1]Boqian WANG;Dingxi WANG;Mohammad RAHMATI;Xiuquan HUANG-.Revisiting the space-time gradient method:A time-clocking perspective,high order difference time discretization and comparison with the harmonic balance method)[J].中国航空学报（英文版）,2022(11):45-58

clocking,reordering

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