Discrete Noise Prediction of Variable Pitch Cross-Flow Fans by Unsteady Navier-Stokes Computations
نویسندگان
چکیده
The unsteady viscous flow fields of a cross-flow fan are computed by time-accurately solving the two-dimensional incompressible Navier-Stokes equations with the unstructured triangular mesh solver algorithms. Based on pressure fluctuation data acquired at the surfaces of 35 rotating blades and stabilizer, acoustic pressures are predicted by the Ffowcs Williams-Hawkings equation. The aerodynamic noise sources of the cross-flow fan are also identified by correlating the acoustic pressure fluctuations with the unsteady flow characteristics during one revolution of the impeller. The present method is applied to the uniform and random pitch fans to investigate their performance and aeroacoustic noise characteristics, especially the frequency modulation of the tonal noise at the blade passing frequency (BPF). @DOI: 10.1115/1.1568356#
منابع مشابه
Unsteady Transonic Aerodynamic Analysis for Oscillatory Airfoils using Time Spectral Method
This research proposes an algorithm for the simulation of time-periodic unsteady problems via the solution unsteady Euler and Navier-Stokes equations. This algorithm which is called Time Spectral method uses a Fourier representation in time and hence solve for the periodic state directly without resolving transients (which consume most of the resources in a time-accurate scheme). Mathematical t...
متن کاملSolution of the Unsteady Discrete Adjoint for Three-Dimensional Problems on Dynamically Deforming Unstructured Meshes
The formulation and solution of the adjoint problem for unsteady flow simulations using the Reynolds-averaged Navier-Stokes equations in the presence of dynamically deforming unstructured meshes is demonstrated. A discrete adjoint approach is used, and the full linearization is built up in a systematic and modular fashion. Discrete conservation in the analysis problem is ensured through the geo...
متن کاملInvestigation of the efficiency of various reactive mufflers by noise reduction and transmission loss analyses
Transmission loss and noise reduction of reactive mufflers are determined by linear acoustic theory and unsteady flow field study, respectively. The effects of extending the inlet tube of the muffler, adding holes to the extension, and the number of holes on both transmission loss and noise reduction are investigated. In noise reduction analysis, the Navier-Stokes equations and k-ε model are us...
متن کاملplunging NACA 0012 aerofoil in a uniform stream of low speeds for different motion parameters by using inviscid version of a three-dimensional unsteady compressible
This research paper presents the CFD analysis of oscillating airfoil during pitch cycle. Unsteady subsonic flow is simulated for pitching airfoil at Mach number 0.283 and Reynolds number 3.45 millions. Turbulent effects are also considered for this study by using K-ω SST turbulent model. Two-dimensional unsteady compressible Navier-Stokes code including two-equation turbulence model and PISO pr...
متن کاملAdjoint-based Unsteady Airfoil Design Optimization with Application to Dynamic Stall
This paper presents the development and application of an adjoint-based optimization method to designing airfoils with the objective of alleviating dynamic stall effects in helicopter rotor blades. The unsteady flow problem is simulated using the NSU2D code, which is a two-dimensional unsteady, viscous, turbulent Reynolds averaged Navier-Stokes (RANS) finite-volume solver. The corresponding adj...
متن کامل