Compound Cycle Engine Velocity Turbine Back Pressure
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Solution Overview
Problem
Existing compound cycle engines with rotary engines have limited available power for turbo compounding and performance, especially at start-up, due to the use of pressure turbines downstream of the turbocharger turbine, which restricts the pressure ratio across the turbines and increases back pressure and thermal loads on the rotary engines.
Innovation Solution
The implementation of a compound cycle engine design that includes at least two rotary units with a velocity turbine positioned between them, drivingly engaged to an output shaft, and a turbocharger with a compressor and pressure turbine, where the exhaust ports of the rotary units are in fluid communication with the velocity turbine upstream of its rotor, allowing for efficient power recovery and minimized back pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a pressure turbine is positioned downstream of the turbocharger turbine, then the turbo compounding system can be implemented, but the available power for turbo compounding is limited and back pressure on the rotary engines increases
Solution Approach 1:
The exhaust flow path is segmented into two separate turbine stages: a velocity turbine positioned between the rotary engines and a pressure turbine positioned downstream of the turbocharger turbine. This segmentation allows the velocity turbine to capture kinetic energy from exhaust pulses without creating back pressure, while the pressure turbine recovers pressure energy downstream, thereby increasing available power for turbo compounding without harming the rotary engines.
Solution Approach 2:
The velocity turbine acts as an intermediary component between the rotary engines and the pressure turbine. It is positioned to receive exhaust flow directly from the rotary engines and transfer processed exhaust flow to the pressure turbine, enabling energy recovery without exposing the rotary engines to harmful back pressure conditions.
2Use of energy by moving object
If a pressure turbine is used downstream of the turbocharger turbine, then energy recovery is achieved, but thermal loads on the rotary engines increase
Solution Approach 1:
The energy recovery process is segmented into two distinct thermal management zones: the velocity turbine operates in a high-temperature zone where it extracts kinetic energy without significant pressure drop, while the pressure turbine operates in a lower-temperature zone downstream. This segmentation allows efficient energy recovery while protecting the rotary engines from excessive thermal loads.
Solution Approach 2:
The velocity turbine serves as a thermal intermediary that reduces the temperature and kinetic energy of exhaust gases before they reach the pressure turbine. This intermediary stage protects the rotary engines from thermal back-pressure while still enabling effective energy recovery in the pressure turbine stage.
3Object-generated harmful factors
If the velocity turbine is positioned between the rotary engines, then back pressure is minimized, but device complexity increases
Solution Approach 1:
The velocity turbine and pressure turbine are merged into a single integrated exhaust energy recovery system with a unified exhaust flow path. The velocity turbine is positioned between the rotary engines and the pressure turbine, creating a combined system that minimizes back pressure while recovering energy through two sequential stages, thereby managing complexity through functional integration.
Data Source
AI summary
A compound cycle engine having an output shaft, at least two rotary units each including an internal combustion engine with the rotor of each rotary unit mounted on the output shaft and in driving engagement therewith, and a turbine including a rotor in driving engagement with the output shaft. The exhaust port of each rotary unit housing is in fluid communication with the flowpath of the turbine upstream of its rotor. The turbine is disposed co-axially between two of the rotary units. The engine may further include a compressor in fluid communication with the inlet port of each housing and a second turbine having an inlet in fluid communication with the flowpath of the first turbine downstream of its rotor. A method of compounding rotary engines is also discussed.