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This paper presents an approach to numerically simulate greenhouse windnoise. The term “greenhouse windnoise” here describes the sound transferred to the interior through the glass panels of a series vehicle. Different panels, e.g. the windshield or sideglass, are contributing to the overall noise level. Attached parts as mirrors or wipers are affecting the flow around the vehicle and thus the pressure fluctuations which are acting as loads onto the panels. Especially the wiper influence and the effect of different wiper positions onto the windshield contribution is examined and set in context with the overall noise levels and other contributors. In addition, the effect of different flow yaw angles on the windnoise level in general and the wiper contributions in particular are demonstrated. As computational aeroacoustics requires accurate, highly resolved simulation of transient and compressible flow, a Lattice-Boltzmann approach is used.

The demand for low noise level in vehicle cabin continues to rise lately. In particular, noise generated by eco-friendly cars such as hybrid and electric ones tends to become lower and lower. In this market environment, the noise contributions caused by HVAC systems are also increasing. Therefore, it becomes increasingly important to accurately predict noise generated by HVAC systems and analyze the noise sources and resolve the noise issue. In this study, direct acoustics prediction approach based on Lattice Boltzmann Method is applied to predict the flow-induced noise from HVAC systems including blower and ducts and find noise sources. In order to validate the simulation result, acoustics measurements are performed on HVAC systems in an anechoic room and the results are compared to each other. A new technique is applied to finding a noise source for a specific frequency and shows improved noise level through modifying the geometry related to noise sources detected by the simulation.

In recent years, vehicle cabin quietness takes a growing importance particularly related to the emergence of hybrid and electric vehicles and “Idle Stop system” vehicles. Demand for quieter car air-conditioner systems is increasingly important also, especially the reduction of the flow-induced noise from the HVAC. In HVAC systems, the rotating blower is one of the main noise sources and the digital solution for predicting and analyzing the blower aeroacoustic noise in the early stage of design is needed for developing a quieter blower. The target of this study is to develop and to validate a flow-induced noise predictive tool for a HVAC blower and to analyze the noise source. In this paper, a low-dissipation, transient, compressible CFD/CAA approach based on the Lattice Boltzmann Method (LBM) is used to predict simultaneously the flow and aeroacoustic radiation of two production blowers.