Overview

Changes in the upstream flow or changes in the flow on the surface of the object is said to be one reason for the noise generated by an object placed in a flow. The main purpose of Quiet Wind Tunnel is to experimentally resolve the mechanism of noise generated by an object surrounded by a flow such as rockets, aircraft, trains, cars, etc. Thus it helps to research and develop eco-friendly products.

Like general wind tunnels, Quiet Wind Tunnels are divided into three categories, namely continuance type, blow-down type, and suction type. An example of continuance type is shown below.

Like general wind tunnels, required devices for Quiet Wind Tunnels differ according to the purposes of tests.
In case of using aerodynamics together with Quiet Wind Tunnel, the following devices are required in general.

Fan: A device that attains specified wind velocity at the test section.
Tunnel Structure: Airway that connects the fan and the test section.
Test Section: Area with uniform airflow where aerodynamic tests and noise tests can be performed with high accuracy.
Anechoic Room: A room where the noise generated by a model that is placed in the test section is measured with high accuracy.
Silencer: A device that reduces the noise transmitted to the test section from the fan.
Heat Exchanger: A device that prevents temperature rise in the wind tunnel.

According to the test purposes or customer's needs, the following devices may be added.

Six-Component Balance: A device that measure aerodynamic force applied to the model.
Traverse System: An ancillary device that allows various measurements inside or outside of the airflow.
Moving Belt: A device that simulates ground effect on a model running on the ground.
Smoke Generator: A device that visualizes airflow around a model.

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