Improving the performance of aeroacoustic measurements beneath a turbulent boundary layer in a wake flow

Experimental measurement and subsequent numerical prediction of the excitation of at plates or car windows beneath a turbulent boundary layer have become important for the development of novel cars and airplanes. A wavenumber spectrum can be used to define the load on a plat caused by the pressure fluctuations on the surface. Wavenumber spectra from measurements are used to validate the numerical predictions of the acoustic and hydrodynamic portions of the pressure fluctuations. When measuring wavenumber spectra, the design of the experiment can have a large in fluence on the outcome. In this paper, the effects of both array design and the application of deconvolution algorithms on the experimental determination of the wavenumber-frequency spectrum are evaluated

Characterization of the pressure fluctuations within a Controlled-Diffusion airfoil boundary layer at large Reynolds numbers

The present investigation targets the generation of airfoil trailing-edge broadband noise that arises from the interaction of turbulent boundary layer with the airfoil trailing edge. Large-eddy simulations, carried out using a massively parallel compressible solver CharLESX, are conducted for a Controlled-Diffusion (CD) airfoil with rounded trailing edge for seven configurations, characterized with a Reynolds number, angle of attack and Mach number. An analysis of the unsteady pressure signals in the boundary layer is proposed in regard to classical trailing edge noise modelling ingredients

Concept for measuring aeroacoustic noise transmission in trains derived from experience gained in aircraft testing

Measuring aeroacoustic noise and its transmission into the passenger compartment of an aircraft provides a way to evaluate the vibrational energy caused by the turbulent boundary layer and other aeroacoustic sources, the transmission path and the sound radiation into the compartment. The measurement results are used to validate numerical models and to identify parameters for a turbulent boundary layer model. This was used in a flight test campaign at the DLR to separate different sources and determine their transmission into an aircraft. The measurement concept and results from the flight test will be presented, whereupon the potential in applying this concept to high-speed train measurements will be discussed