A cost-effective simplified hemi-anechoic chamber for engine development purpose

摘要

To enhance our NVH facility as well as the project confidentiality concern, we, Industrial Technology Research Institute, decided to establish our own engine acoustic chamber by modifying the existing test laboratory. However, under budget and space limitations, it is nearly impossible to build a standard engine hemi-anechoic chamber. Nevertheless, a "simplified" but proved to be "effective" hemi- anechoic chamber was built. The acoustic chamber was finished within four months from feasibility evaluation to final sign-off tests. The cost for the renovation was below US$ 17,000. In this paper, the purpose and layout of the acoustic chamber will be briefly explained. Then, the method and tests to verify the chamber specification will be illustrated in detail. The corrective modification to achieve the design specification is also presented. Reverberation time measurement by impulse method was used to verify the performance of acoustic chamber. It is shown that the equivalent sound absorption area was doubled or tripled for most of the frequency ranges after hemi-anechoic chamber construction. Also, the factor of environmental correction for this chamber can satisfy the requirement of ISO-3744. It is concluded that this simplified hemi-anechoic chamber is a successful example of multidisciplinary optimization among design purpose, performance, cost and space.