Wind tunnel

The Italian wind tunnel

Newton wind tunnel

proud of our project

The Newton laboratory has an installation of a 280 kWatt subsonic wind tunnel. The air is designed to flow in a closed return wind tunnel, Goettingen type.
The test facility has been built to run with either an open or closed test section, as needed for particular experimental program. The required electric energy required is produced by mean of a power generator fully integrated with the wind tunnel.

Technical specifications

General, Test Section, Test Chambers, Fans, Instrumentation, Control and Data Acquisition Station

The project

Installation

Testing

Test sections

The wind tunnel has been designed to allow easy replacement of the converging and diverging elements, currently providing three possible 5m long test sections.

Test section	Maximum speed	Contraction ratio (nozzle)	Length to hydraulic diameter ratio
1,25m x 1,25m - A=1,6mq	240 kmh	10,2	4
1,5m x 1,5m - A=2,3mq	190 kmh	7,1	3,3
1,9m x 1,9m - A=3,6mq	125 kmh	4,4	2,6

Test section A

Test section B

Test section C

Sample dimensions

Experiments to obtain aerodynamic parameters that affect automobile performance, engine cooling, brake cooling and wind noise are made with either at full scale or with scale models.
A key issue for automobile testing is the blockage based on frontal area= the ratio of the model frontal area to the test section area.
The flow around automobiles is often more characteristic of “bluff bodies” than of “streamlined bodies”: this means that there is always a sizable region of separated flow. The wind tunnel test section needs to be sufficient long so that these separated flow regions “close” before encountering the end of the test section and the entry of the diffuser.
In such case it is really helpful to use Newton Wind Tunnel in the open test session configuration.
For experiments with large objects in which the model is held stationary during data gathering and the maximum speed is below 0,3 Mach (350 kmh) it is possible to apply the similarity approach in order to work on a scaled model.
By keeping the same Reynolds number the model and the full scale flows will be dynamically similar: the non dimensional functions for fluid velocity components, pressure coefficients, density, viscosity, the force and the moments will be the same.

Actual dimensions

Size to scale

Dynamically similar

Test models

It is possible to realize test models starting from the 3D CAD drawing to the final CNC sample.

CAD production

3D extrusion models

Numerical control models

Measurements on the model

Force and moments, Pressure mapping, Surface flow visualization

Force and moments

At present time the force and moments to calculate the aerodynamic forces are acquired by mean of n. 3 load cells and n. 3 torque meters.
For the actual tests regarding the aerodynamic characteristic of helmets this system has been embedded inside a standard headform.

Pressure mapping

The model can be special prepared in order to accommodate small tubes (2mm diameter) to acquire the local pressures. At present time up to 18 pressure locations can be acquired.

Surface flow visualization

Information about the flow on the surface of the model being studied helps to investigate stagnation point locations, separation lines, location of boundary layer transition. In Newton lab we commonly use a smoke generator or, alternatively tufts. The tufts being light and flexible will align themselves with the local surface flow as a result of direct aerodynamic forces.