Ivan Volkov, a designer from Kazan, has patented a new gas turbine engine scheme for gas turbine units. The developer proposed using part of the compressed air to control the flow inside the diffuser, which allows for shortening its length and reducing the overall dimensions of the power unit.
After the last compressor stage, the flow is divided into three parts. The main mass of air passes through the straightening apparatus and enters the diffuser before the combustion chamber.
Two peripheral flows are directed into closed annular cavities and then return to the diffuser walls through small tangential openings.
Jets of compressed air accelerate the boundary layer and prevent the flow from separating from the surface at a larger diffuser opening angle. The documentation indicates the possibility of increasing the divergence angle to 36°.
This allows the air to expand more within a shorter diffuser, and its speed before the combustion chamber decreases. This reduces hydraulic losses and equalizes pressure before the flame tube.
From the editors: from a compactness perspective, the scheme looks promising. However, it is worth remembering that using compressor-compressed air for blowing reduces the overall working fluid flow through the combustion chamber, which can worsen thermodynamic efficiency and reduce the net efficiency of the unit.