What do you mean by a transonic wind tunnel?
[tran′sän·ik ′wind ‚tən·əl] (engineering) A type of high-speed wind tunnel capable of testing the effects of airflow past an object at speeds near the speed of sound, Mach 0.7 to 1.4; sonic speed occurs where the cross section of the tunnel is at a minimum, that is, where the test object is located.
How are wind tunnels classified?
Wind tunnels are classified as low-speed or high-speed; they are further classified as subsonic (80 percent of the speed of sound), transonic (about the speed of sound), supersonic (up to 6 times the speed of sound), hypersonic (6 to 12 times the speed of sound), and hypervelocity (over 12 times the speed of sound).
Are there supersonic wind tunnels?
A suction type continuous operation supersonic (up to Mach 1.8) wind tunnel for investigations into subsonic and supersonic air flow around two dimensional models.
How do you calibrate a wind tunnel?
Calibration Process To perform this task, the probe is held in a known flowfield generated by our calibration wind tunnel. We measure the pressures for a matrix of points by changing the angle-of-attack of the probe in the air flow. With these results we calculate the calibration factors for the probe.
How do you calculate static pressure in a wind tunnel?
To measure the pressure, long thin tubes connect the taps to a pressure transducer located outside of the wind tunnel model. In this figure, the transducer is shown in a schematic drawing. The transducer measures the difference in pressure between the pressure in the tube and a reference pressure.
How do you measure forces in a wind tunnel?
In some wind tunnel tests, the aerodynamic forces and moments on the model are measured directly. The model is mounted in the tunnel on a special machine called a force balance. The output from the balance is a signal that is related to the forces and moments on the model.
Which part of the wind tunnel has the lowest flow speed?
For low speed tunnel operation, the test section has the smallest cross-sectional area and the highest velocity within the tunnel. Leaving the test section, the air enters the diffuser where it is expanded and slowed before returning to the fan. Again, the diffuser is employed to minimize losses in the tunnel.
What is flow uniformity in wind tunnel?
A good quality wind tunnel will have a flow uniformity of 0.5- 2% and turbulence intensity of 0.5-2%. It should provide temperature uniformity within 0.1-0.5oC at the inlet of the test section [1]. To achieve uniform, high quality flow in the test section, the settling chamber and the contraction area are used to.
What is contraction ratio in wind tunnel?
In the case of wind tunnels for civil or industrial applications, a contractions ratio between 4,0 and 6,0 may be sufficient. With a good design of the shape, the flow turbulence and non-uniformities levels can reach the order of 2,0%, which is acceptable for many applications.
What are the applications and uses of wind tunnel experiment?
Wind tunnels provide a concentrated stream of air in a vertical or horizontal flow. Quite often wind tunnels are used in the testing of products, such as seen in the automotive industry, to develop aerodynamic designs. Wind tunnels are also utilized for recreational applications such as indoor skydiving facilities.