Abstract
Acoustic properties of resonators installed in vehicle intake system are influenced by the high-speed airflow passing through, which causes errors between practical application and bench tests. In this paper, a test bench with airflow for measuring the resonator transmission loss is developed based on the principle of two-load method. Equipment types are selected and parameters calculation is presented. Effects of sound source protection devices on the performance of sound source are studied experimentally. A resistance resonator and several dissipative mufflers are mounted at the outlet of the vortex air pump to reduce airflow noise and verified to be effective. Finally, the transmission loss of a multi-chamber perforated resonator is measured with the developed test bench and effects of airflow on resonator acoustic properties are analyzed.
Highlights
In order to eliminate the broad band noise excited by turbocharger, multi-chamber perforated resonators are installed in vehicle intake system, in which sound wave propagation is usually accompanied with high speed airflow, especially at the outlet of the turbocharger
The objective of the present study is to develop a high-efficiency test bench with airflow based on the two-load method for measuring the resonator TL and pressure drop at the same time
In order to reduce the serious impacts of airflow noise and sound source noise radiation on testing precision, a resonator and four dissipative mufflers are mounted at the outlet of fan and layers of sound-absorbing cotton are covered on the speaker box
Summary
In order to eliminate the broad band noise excited by turbocharger, multi-chamber perforated resonators are installed in vehicle intake system, in which sound wave propagation is usually accompanied with high speed airflow, especially at the outlet of the turbocharger. Neglect of the airflow influence on resonator acoustic performance at high Mach numbers will bring great error It has become an essential requirement to construct a whole set of test bench with high test accuracy but relatively simple structure, for experimental design and optimization of resonators and for validation of resonator performance prediction theories. Traditional two-load method test devices can accurately measure the resonator TL, while distance between microphones is not adjustable and the main pipe diameter often mismatches the resonator inlet/outlet, requiring a lot more experimental preparation time. The objective of the present study is to develop a high-efficiency test bench with airflow based on the two-load method for measuring the resonator TL and pressure drop at the same time.
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