@phdthesis{Sharma2019, author = {Sharma, Sparsh}, title = {Stochastic modelling of leading-edge noise in time-domain using vortex particles}, doi = {10.26127/BTUOpen-5085}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus4-50858}, school = {BTU Cottbus - Senftenberg}, year = {2019}, abstract = {The conceptual designing of rotating machines such as fans, wind turbines, contra-rotating open rotors and helicopter blades require low-cost, easy-to-run tools which allow quick noise assessments and optimization analyses underlying this phenomenon. The state-of-the-art numerical and experimental methods are far more expensive to conduct an optimisation study, whereas inexpensive methods like the analytical ones can have significant errors in realistic geometries at high-frequency ranges, higher angles of attack. The response to large coherent disturbances and the statistical modeling of turbulence is required because turbulence, by far its nature, is stochastic. Determining the accurate unsteady response of airfoil is crucial for noise prediction. The primary goal of the project is to develop a new low-cost and easy-to-use numerical technique for aero-acoustic designs, focused primarily on airfoil-turbulence interaction. The development of the statistical method is divided into three sections; namely - 1) calculating the background flow, 2) modeling of statistically optimized inflow disturbance, 3) constructing a vortex database to predict the noise in multiple flow fields characterized by different values of turbulent intensities and length scales. In the framework of this work a new approach to model inflow turbulence, a significant noise-generating element, is suggested, which does not depend on heavy computations requiring supercomputers. Through this approach, the influence of turbulence parameters on the noise generated in turbomachinery can be quantified. The approach also considers the geometrical parameters of the airfoil in the noise prediction. The background flow is numerically simulated via solving the vorticity transport equations in the Lagrangian form (vortex methods). The acoustic influence of a finite number of vortices, characterized by all the possible combinations of size, circulation and injection position/time defined using the ranges of probability distribution functions, released from injection points upstream of the airfoil are precomputed and stored in a matrix. The method is computationally inexpensive compared to classical vortex methods since the effect due to particles are precomputed, stored in a/an matrix/array. The matrix can be called as a library while predicting the noise from a specific airfoil.}, subject = {Leading-edge noise; Aeroacoustics; Ffowcs-Williams Hawkings; Broadband noise; Airfoil-turbulence interaction; Tragfl{\"u}gelvorderkantenschalls; Breitbandger{\"a}usch; Tragfl{\"a}chenger{\"a}usch; Aeroakustik; Zeitbereich; Tragfl{\"u}gel; Vorderkante; Tragfl{\"u}gelumstr{\"o}mung; Str{\"o}mungsakustik}, language = {en} }