A novel dual attention network for sparse reconstruction of turbine blade surface fields

Achieving accurate and robust reconstruction of turbine blade surface field from randomly distributed sparse sensors has been a longstanding challenge, which is of high importance for cascade experimental data processing and gas turbine operation and maintenance. As a solution to this problem, this work proposes a novel dual attention network, which consists of a spatial analysis network (SAN) and a multi-scale shifted windows transformer network (MS-SwinT), for arbitrarily positioned sensors of any number that exceeds inferior limits. The new network is examined against a case study of 3D flow in a classical axial turbine blade geometry with complex wave structures. Upon integrating multilayer perceptron with shared weights and attention units, permutation invariance is achieved, and the prediction results are independent of the input order of the measurements. The number of sensors N_s and the isentropic exit Mach number (Ma_2s) are the pivotal determinants of the flow field reconstruction quality. The proposed method requires 32 measurement points (N_s = 32) per side to ensure the reconstruction precision, corresponding to a super-resolution ratio of r_sup = 1024. Besides, MS-SwinT determines the reconstruction quality of the joint model at small Ma_2s, whereas the deviation in boundary conditions inferred by SAN emerges as the primary factor for the reduced performance at higher Ma_2s. The joint model can enhance the spatial resolution of experimental data. Individually, the SAN facilitates the inference of boundary conditions from limited measurements to assist the control systems in decision-making. MS-SwinT serves as a powerful tool for virtual experiments, improving design efficiency by reducing the need for physical experiments and data acquisition costs. The case study demonstrates the great potential of the proposed method in improving the quality of surface field construction with sparse and random data, which is of high value for future applications in gas turbines.