TsAGI tested the air intake of the impeller propulsion system of a regional aircraft

Photo by © TsAGI Press Service

Within the framework of the research project Integral-RS the Central Aerohydrodynamic Institute together with the Baranov Central Institute of Aircraft Engineering and the S.A. Chaplygin SibNIA FAU are working on the development of a regional aircraft with an impeller electric propulsion system, the press service of TsAGI reported.

The electric aircraft will be able to take off from short runways typical for remote municipalities. TsAGI believes that the aircraft will occupy the niche of regional aircrafts such as An-24 and Yak-40, which still continue to perform commercial transportations in Russia.

To solve the problem of reducing the length of runways for takeoff and landing, it is necessary to increase the lifting power of the wing. For this purpose, an electric impeller distributed propulsion system (IDEPS) is planned to be used in the new machine. TsAGI is conducting research, including wind tunnel tests, to optimise the performance of the engine air intake of such an aircraft.

“The technology of energy-based streamline control on the basis of an impeller SU, which we are developing together with the N.E. Zhukovsky Institute, makes it possible to significantly increase the wing lift coefficient of a regional aircraft. Thanks to this it is possible to significantly reduce the length of run-up and run-down of the airliner, which is important for remote areas of our country with a network of airfields with a short runway,” said Evgeny Pigusov, Deputy Head of the Centre for Complex Integration of Technologies of the Federal Autonomous Establishment TsAGI.

Impeller is a rotating wheel with blades or vanes enclosed in a ring. When the impeller rotates, air is sucked in through the inlet opening and compressed, increasing the flow velocity and its pressure at the outlet. This creates jet thrust. TsAGI developed a number of elements of the impeller propulsion system, including the air intake. One of the stages of studying the effectiveness of the technology of integration of the airframe and impeller DEP were studies of the characteristics of the air intake device at cruising flight modes.

The researchers measured the gas dynamic parameters of the airflow at the engine inlet, studied the total pressure profile in front of the air intake and visualised the gas flow path using various methods, including the method of visualising surface currents using particle images. The data obtained will be used in flight testing of the prototype wing compartment on a flying laboratory.

The tests as part of the prototype wing compartment model were conducted in the wind tunnel of direct-flow engines. The operation of the air intake device IDEPS was modelled at cruising flight mode in the speed range from 136 to 204 m/s (490-734 km/h). During the experiments, the gas dynamic parameters of the air flow at the engine inlet were measured and the total pressure profile in front of the air intake was investigated. Also, using the “thick” oil* method, the trajectory of gas flow on the surface of the model in the area of the air intake device was visualised.

As a result, the flow characteristics at the engine inlet under flow rate modelling were obtained, such as the full pressure recovery coefficient, the dependence of air intake parameters on the angle of attack, glide and velocity. These data will be used in preparation of flight tests of the prototype wing section on the Yak-40LL flying laboratory at SibNIA.

* PISFV – Particle Image Surface Flow Visualisation, a method of visualising surface flows using particle images, developed at TsAGI