Perm scientists have found a way to make planes quieter

Engine noise Aircraft is considered a side issue of the aviation industry. However, the lack of publicity does not negate the impact of this factor on the environment and even human health.


This is especially true for areas and zones adjacent to airports. The statement is also true for airport employees.

The issue of reducing aircraft noise has recently been given additional priority. Moreover, the first results of research into the search for an optimal method of "silencing" an aircraft engine have appeared.


Specialists from the Noise Generation and Modal Analysis Laboratory at Perm Polytechnic University conducted unique experiments. Scientists studied all possible configurations of aircraft engine nozzles. Engineers assessed their ability to absorb noise in various frequency spectra – from low at 500 Hz to high in the range above 1000 Hz.

Today, the following types of nozzles are considered to be frequently used in aircraft construction:

✅ conical
✅ chevron
✅ corrugated

PNIPU researchers came to the conclusion that the most effective are modernized corrugated nozzles. Unlike standard ones, they are equipped with an increased number of petals.

Let us recall that the occurrence of noise during aircraft operation is associated with turbulent flows of exhaust gases. Their high emission speed interacts with the air and the body of the aircraft.

Traditionally, to combat the sound problem, engineers resort to increasing the engine diameter. This reduces the exhaust flow speed, but an additional design feature appears - low-frequency vibrations are amplified.

Another method was to change the location of the engine installation. To reduce noise, they are installed above the wing. And again, solving one problem creates another. Low-frequency vibrations become less, but in this case the flow already has a negative effect on the wing surface.

This is how noise-absorbing devices appeared – chevron and corrugated nozzles. But they help to combat the problem only partially. For example, the first type has a triangular “pattern”, which effectively absorbs low-frequency noise, but amplifies it in the high-frequency spectrum.

Modern corrugated nozzles are functionally almost the same. Then scientists from Perm Polytechnic University began experimenting with the number of petals.

If the design is used on modernized nozzles, the efficiency increases. The hypothesis was confirmed during tests in the acoustic laboratory of PNIPU.

The measurements were carried out using 3D printed models and specialized equipment. The research conditions were close to real ones.


A special fan was responsible for generating a 45 kW flow, and the volume level was recorded using 6 microphones.

Scientists noted that at 12 kHz, chevron nozzles are capable of reducing low-frequency noise by 1,3 dB. At the same time, modernized 12-petal corrugated samples provide a reduction of 2,5 dB.

The efficiency has been confirmed across the entire frequency spectrum, not just in the "low zone". PNIPU specialists are confident that the introduction of the innovative noise-reducing design will help improve the acoustic characteristics of Russian aircraft.