Central Aerohydrodynamic Institute
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TsAGI Scientists Develop Equipment to Study Non-Stationary Air Flow

8 June 2022

Non-stationary total/static pressure probe with reference sensors

Modern manufacturers of civil aircraft technology have been imposing increasingly strong requirements to the accuracy of aircraft model aerodynamic tests. Correspondingly, there is growing demand for studying both stationary and nonstationary parameters that affect the accuracy in wind tunnel flow.

Nonstationary parameters of the air flow include, in particular, oscillations of total and static pressure in wind tunnel test section. Knowing these parameters is essential for enhancing test methods. Scientists at TsAGI (a part of NRC “Zhukovsky Institute”) developed a method which allows measuring these parameters directly in a wind tunnel.

At the first stage, TsAGI designed and manufactured a special tool—Pitot- Prandtl tube, an extended metallic tube with holes taking the flow. Structurally, the tool protects the pressure sensors installed inside from damage by small particles that wind tunnel flow may contain.

‘So here we have a complicated question: How can nonstationary pressure be measured precisely? We have developed a mathematical model for determining pressure values before the receiving openings, according to the data from the sensors of the probe,’ said Yelena Anokhina, First-Category Engineer, Department for Aircraft Aerodynamics, TsAGI.

TsAGI scientists developed calibration methods for such probes. There were two different assessments of the probe with reference sensors (i.e. measuring pressure without any distortion) installed inside and near the reveiving opening. In the first case, sound generator and acoustic systems simulated frequencies from 20 to 11,000 Hz. In the second case, impulse impact was preformed with rubber ball explosion. Both cases proved that the mathematical model could analytically restore the inner sensors’ data up to the reference device values.

Then, the non-stationary total/static pressure head was placed in the T-128 wind tunnel test section. This provided the first-ever measurement of pressure oscillations in the wind tunnel. Furthermore, delay of the stationary air tubes was studied. All this will allow TsAGI to obtain more precise parameters of the tested aircraft model.

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