Abstract Fan noise can form a significant part of the vehicle noise signature and needs hence to be optimized in view of exterior noise and operator exposure. Putting together unsteady CFD simulation with acoustic FEM modeling, tonal and broadband fan noise can be accurately predicted, accounting for the sound propagation through engine compartment and vehicle frame structure. This paper focuses on method development and validation in view of the practical vehicle design process. In a step by-step approach, the model has been validated against a dedicated test-set-up, so that good accuracy of operational fan noise prediction could be achieved. Main focus was on the acoustic transfer through the engine compartment. The equivalent acoustic transfer through radiators/heat exchangers is modeled based on separate detailed acoustic models. The updating process revealed the sensitivity of various components in the engine compartment. Unsteady CFD included the build-up of a sliding mesh model which was analyzed using the DDES method. After convergence, time data of blade surface pressure were exported in CGNS format. These pressure data were used to generate rotating dipole sources in acoustic FE analysis and predict the fan noise response in frequency domain at two selected rpm. Post processing includes the predicted noise at target microphone positions as well as colormaps of sound pressure distributions that can guide to the development of countermeasures. Introduction In the presence of increasingly stringent noise requirements, using simulation in the early design phases is a crucial element in obtaining a competitive advantage for the new product in development. Such frontloading the NVH design also reduces the time to market. Noise of off-highway vehicles typically includes a significant fan-induced component, due to the cooling requirements of engine and hydraulic installations. Aero-acoustic simulation of fan noise was developed into a commercially available technology and has been constantly refined in view of solution accuracy and speed. Recent enhancements include the simulation of broadband components. For successful use in vehicle design, it is still necessary to develop and validate the method for the specific application. Purpose of the work presented in this paper is securing the methodology for the use in off-highway vehicle design. This includes providing representative input parameters for use in the analysis process and making sure the accuracy obtained is sufficient to give guidance for design modifications and confirming overall level requirements are met. Fan Noise Simulation Method Fan noise has been simulated using a hybrid approach including CFD for the flow and acoustic FE for the acoustic propagation (see last section of this paper for definitions/abbreviations). This method uses the analogy of Ffowcs-Williams and Hawkings [ 1] for the construction of rotating dipole sources in the acoustic model. For CFD simulation, a sliding mesh model needs to be built up, in which a rotating domain including the fan blades is contained in a fixed part. Mesh refinements need to consider expected boundary layer effects, as well as necessary time steps to capture the flow and the highest acoustic frequency to be modeledFan Noise Prediction for Off-Highway Vehicle 2017-01-1834 Published 06/05/2017 Dirk von Werne Siemens Industry Software Prasanna Chaduvula Siemens PLM Software Patrick Stahl, Michael Jordan, and Jamison Huber Bobcat Company Korcan Kucukcoskun and Mircea Niculescu Siemens Industry Software CITATION: von Werne, D., Chaduvula, P., Stahl, P., Jordan, M. et al., "Fan Noise Prediction for Off-Highway Vehicle," SAE Technical Paper 2017-01-1834, 2017, doi:10.4271/2017-01-1834. Copyright © 2017 SAE InternationalDownloaded from SAE International by Univ of California Berkeley, Saturday, August 04, 2018After subsequent convergence of RANS, URANS and DDES analysis, pressure time data on