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For measurements of unsteady flow phenomena with multi-hole pressure probes, pressure transducers are integrated in the probe near the probe tip. The application of additive manufacturing enables a wide variation in probe geometries for complex use cases. The spatial characteristics of the unsteady probe are determined by the steady state calibration in a known free-jet wind tunnel. Furthermore, the acoustic/pneumatic line-cavity system, that emerges inside the channels of the probe, is investigated in detail in the temporal calibration. In order to realize multi-hole probes with higher temporal resolution, which can be operated in harsh environments, a fiber-optic pressure sensor is developed. The measurement principle of the fiber-optic sensor is based on the Fabry-Pérot interferometer effect. The sensor is operated differentially with a pressure capillary by either pressurizing the sensor or using the surrounding static pressure as the reference pressure. Besides calibration of the sensor, comparisons with a state-of-the-art piezo-resistive pressure transducer have been performed. The focus of this work is on the reproducibility of both frequency response and amplitude.

This paper presents a reduced-order modeling approach based on recurrent local linear neurofuzzy models for predicting generalized aerodynamic forces in the time domain. Regarding aeroelastic applications, the unsteady aerodynamic loads are modeled as a nonlinear function of structural eigenmode-based disturbances. In contrast to established aerodynamic input/output model approaches trained by high-fidelity flow simulations, the Mach number is considered as an additional model input to account for varying freestream conditions. To train the relationship between the input parameters and the corresponding flow-induced forces, the local linear model tree algorithm is adopted in this work. The proposed method is tested exemplarily with respect to the AGARD 445.6 configuration in the subsonic, transonic, and supersonic flight regimes. It is shown that good conformity is obtained between the reduced-order model results and the respective full-order computational-fluid-dynamics solution. A further comparative analysis in the frequency domain in conjunction with a classical flutter analysis confirms the validity of the approach. Finally, the method's potential for reducing the computational effort of aeroelastic analyses is demonstrated.

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