VTOL Turbofan Concept
 

Hello,

I am presenting an architecture study and advanced pre-sizing of a compact turbofan concept specifically intended for VTOL applications with low acoustic signature (perception) and operation in constrained environments. The AEU (Advanced Embedded Unit) architecture is based on a high level of integration, with independent N1 and N2 rotating assemblies, a reverse-flow annular combustion chamber, and a design philosophy aimed at reducing mechanical complexity and the need for active sealing systems (the so-called “Zero Seal” approach).

This work does not represent a certified design nor a finalized industrial configuration. All numerical values, geometries, and performance figures presented are order-of-magnitude estimates derived from preliminary analyses and engineering assumptions, with the objective of assessing feasibility, architectural consistency, and the comparative positioning of the concept with respect to existing propulsion solutions in the 1 to 3 MW power class.

My goal is simply to gather critical feedback, positive or negative, on the consistency and viability of this architecture.

https://cimg7.ibsrv.net/gimg/pprune....28a6ae8b5e.png https://cimg4.ibsrv.net/gimg/pprune....211d361223.png
https://cimg3.ibsrv.net/gimg/pprune....3e3d538a7d.png

Interesting concept. How do you avoid reingesting exhaust gases, both leakage between stages and at the air inlet. I assume exhaust gas does another 180 and goes through the fan?

Turbine stage count is usually much lower than compressor stage count. How is this handled?

VSVs look like they would be impractical as the operating mechanisms would be in or through the exhaust ducts.

For VTOL applications I assume you want as high a bypass ratio as possible (due to low speed operation).

If you chose a DEP route instead of turbofan, I wonder whether you could bury the motor-generator(s) inside the compressor as well.

Reminds me of the GE CF700.
https://www.researchgate.net/figure/...fig3_321802051

Concept Turbofan VTOL
 

Hello,
I would be happy to send you a PDF file that explains in detail the operating principle of the VTOL-AEU-10000N turbofan concept, but I do not yet have authorization from PPRuNe. I need to wait until a certain number of views has been reached.
In the meantime, I can share the first page of the document by copying and pasting its contents.AEU Turbofan Concept – 10,000 N Class Concept Overview

The AEU-Zero Seal turbofan is a dual-flow turbojet concept specifically designed for VTOL applications, with a primary objective: drastically reducing ground noise emissions.

Its atypical architecture, based on a highly integrated configuration and a ‘Zero Seal’ design philosophy— referring to the minimization of active sealing systems rather than the physical absence of seals—ejects the hot exhaust gases upstream of the engine (skyward side) at low velocity, enabling an external noise level below 76 dBA at 10 m.

All propulsive thrust is generated by the bypass fan. The low-pressure turbines absorb nearly all the energy of the hot gases, resulting in a residual hot-core thrust below 5%, with a target value of approximately 3–4%. Unlike conventional turbofans, the AEU architecture does not use concentric shafts. Instead, it relies on innovative multi-path disks (two- or three-path disks), in which a central compressor is surrounded by a

lowpressure turbine, itself surrounded by the fan. This configuration allows the primary flow to be split into concentric counter-flow paths through an inverted, smoothly curved combustion system (180° inversion with an effective turning angle of approximately 18°).

Coplanar rotors and stators provide exceptional modularity and record compactness. Radial pressure balance is optimized, with a pressure differential ΔP < 0.09 bar, as indicated by preliminary analytical simulations.

Operating Principle of the AEU Concept

(schematic representation – not scaled for the 10,000 N configuration)

The air intakes and exhaust nozzle shown are indicative only and require detailed aerodynamic and thermal analyses for validation. All numerical data provided (geometries, flow rates, mass estimates) are preliminary values, based on design assumptions that have not yet been experimentally verified.

The illustrations presented are intended to convey the general operating principle only and do not constitute an industrial design basis. They must be complemented by CFD studies, FEM structural analyses, and mechanical testing prior to any hardware realization.

"The concept images cannot be included in the copy-and-paste content."
Scope and Design Matury
The AEU-Zero Seal engine is presented at an advanced pre-dimensioning stage. The concept emphasizes architectural simplicity, acoustic performance, and VTOL compatibility rather than extreme cruise efficiency. The absence of concentric shafts, the use of stator-only inter-stage interfaces, and the strong radial pressure balance collectively contribute to reduced mechanical complexity, improved durability, and simplified sealing solutions.

The concept is free of intellectual property constraints and is not protected by any active patent.
This is a fully innovative concept...

Regards

Hello,
I am currently unable to attach the PDF detailing the Turbofan AEU-VTOL concept due to forum restrictions. Should you need further information or a summary, please let me know.
Regards