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In this study, a new practical design method (tool) for engine sound quality in a car interior is proposed. The tool can automatically create the target interior sound using the psychoacoustic index ‘powerfulness’ based on subjective tests. Moreover, it can calculate the intake noise characteristic to create the target interior sound and select the suitable intake specification from the prepared database. By using this method sound engineering can be easily and effectively carried out without manufacturing an experimental car.

Using a higher order vortex panel method, three dimensional free wake analyses for a rotor in hover are carried out. The purpose of this paper is to propose new methods being able to incorporate wake deformations due to wake-ground interactions into performance predictions. Both rotors at isolated and at close proximity to arbitrary shaped ground surfaces are investigated. The blade is modeled as a lifting surface with one row of cells (equivalent to Weissinger's L model). The wake is divided into the adjoining, near and far regions. The ground is approximated by the quadrilateral panels. The first two regions of the wake are modeled by triangular shaped panels with linear vorticity distribution which are adopted by their flexibility for roll up deformations of the wake. A semi-infinite vortex cylinder with the constant radius is substituted for the far wake to avoid instabilities of the wake geometry.