By Isabelle Robinson, M.Sc.Feb 20 2018The University of Bristol has developed a new technique using acoustics to detect blockages in pitot tubes. Similar to the method used to find blockages in the ears of newborn babies, it is believed to be able to do the same with pressure sensors, known as pitot tubes.
These pressure sensors have been developed to allow pilots to become aware of a blocked tube before a critical situation arises. The technique called ‘Acoustic Reflectometry’, can be used in a variety of applications.
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The technique has been published in the ‘Journal of Aircraft’ which is dedicated to an “advancement of the applied science and technology of airborne flight.” The aim of the journal is to collate original scientific publications that could be used to develop technology in the aerospace industry.
Since the development of aircraft, Pitots have been the cause of numerous plane accidents, most notoriously, the Air France Flight 447 from Rio on July 1st, 2009 which killed 288 people. Pitot tubes are fitted on the wing of an aircraft to measure the speed and are therefore vulnerable to blockages such as ice and insects. It is vital that these blockages are detected before an incident can occur.
This is not the first time that this technique has been proposed. However, it is the first time that any experimental data has been published. Senior lecturer in the Department of Aerospace Engineering of the University of Bristol, Dr. Thomas Rendall, co-authored the paper used a CT scanner to x-ray three pitot-statics for two commercial aircraft.
An acoustic study was undertaken with the aim to find the variation between tubes that were blocked and unblocked from reflected acoustic waves. During the experiment that used a range of objects to block the tubes to simulate the differing types of blockage that an aircraft could encounter. These included tape, insects, foam, and metal.
The experiment showed the researchers that this was a reliable technique for detecting blockages in pitot tubes. The technique even worked for non-cylindrical tubes and tubes of varying sizes as long as there was a simple cylindrical tube placed the full length of the pressure duct.
In principle, the method could be adopted to help inform pilots if Pitots are blocked before they take off, or if they subsequently become blocked during a flight.
Dr. Thomas Rendall
This is just the first stage of testing - the experiment is only based on a pitot tube used in an aircraft on the ground. It is important also to test the system for in-flight operation. Therefore, the next phase of the research is to test the technique using realistic simulations of flight. This would require much more detailed noise data from real aircraft in use.
In addition to this, the system must be made smaller in order to be used in real-world airplanes. This is due to the tight confines of the aircraft itself. The research team behind this project have recommended that the industry start testing an operable flight system with the data and equipment that is now available to them.
This story is reprinted from material from theengineer.com, with editorial changes made by Azo Network. The original article can be found here.
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