Compound Cycle Rotary Engine for Low SFC
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing engine technologies face challenges in achieving low specific fuel consumption (SFC) at high power to weight ratios, particularly in propulsion systems requiring 500 to 3000 shaft horsepower, as gas turbine engines have high SFC and intermittent combustion engines have low power to weight.
Innovation Solution
A compound cycle rotary engine system that combines features of gas turbine and intermittent combustion engines, utilizing a rotary engine with a displacement of 1 to 10 liters, operating at specific pressure and temperature ranges, and featuring a compressor, intercooler, and two turbines in series to extract energy from exhaust gases, optimizing the Miller cycle for high power output and low SFC.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a gas turbine engine is used, then high power to weight ratio is achieved, but specific fuel consumption increases
Solution Approach 1:
The engine cycle is segmented into two distinct phases: an intermittent combustion phase (rotary engine) that provides efficient fuel combustion, and a continuous expansion phase (turbine) that extracts additional energy from exhaust gases. This segmentation allows each phase to optimize for its specific function, resolving the contradiction between power density and fuel efficiency.
Solution Approach 2:
The invention merges features of two different engine types (intermittent combustion engine and continuous flow turbine) into a single hybrid system. The rotary engine provides efficient combustion while the turbine recovers energy from exhaust, combining the advantages of both technologies to achieve high power-to-weight ratio with low specific fuel consumption.
2Use of energy by moving object
If a reciprocating engine is used, then low specific fuel consumption is achieved, but power to weight ratio decreases
Solution Approach 1:
The invention transitions from static reciprocating motion to dynamic rotary motion. The rotary engine eliminates reciprocating masses and enables continuous rotation at high speeds, dramatically increasing power output for a given weight while maintaining efficient combustion characteristics through optimized chamber geometry and timing.
Solution Approach 2:
The invention replaces the traditional reciprocating piston mechanism with a rotary combustion chamber that rotates continuously. This substitution eliminates the need for complex valve trains and reciprocating components, reducing weight and mechanical losses while maintaining efficient fuel combustion, thereby achieving both low SFC and high power-to-weight ratio.
3Power
If CI engine operating speed is increased, then power output increases, but structural weight must increase to contain higher pressures and temperatures
Solution Approach 1:
The invention changes the operating parameters by transitioning from high-pressure/temperature CI combustion to a rotary combustion mode that operates at lower peak pressures and temperatures. This parameter change allows the engine to achieve high power output through increased rotational speed rather than increased pressure, eliminating the need for heavy structural reinforcement.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system achieves low SFC and high power to weight ratios by efficiently utilizing exhaust gas energy through the series turbine arrangement and optimized rotary engine operation, enhancing power output while reducing fuel consumption.
Implementation Method 1
means for supplying inlet air at a pressure in the range of from 0.30 to 0.50 MPa (3.0 to 5.0 atmospheres) and a temperature in the range of from 66 to 121 degrees Centigrade (150 to 250 degrees Fahrenheit) to said rotary engine; said air supplying means comprising a compressor
Implementation Method 2
a first turbine connected to the compressor by a shaft, said first turbine receiving said exhaust gas from said engine and reducing exhaust gas pressure
Implementation Method 3
a second turbine having an output shaft, said second turbine receiving said exhaust gas from an outlet of said first turbine
Implementation Method 4
means for extracting energy from the exhaust gas of said engine, said means providing an external expansion ratio in the range of 2.0:1 to 7.0:1
Data Source
Figure 1~2
Figure 3
AI summary
A compound cycle engine system (10) has a rotary engine (24), which rotary engine generates exhaust gas. The system further has a compressor (16) for increasing the pressure of inlet air to be supplied to the engine to a pressure in the range of from 3.0 to 5.0 atmospheres and an intercooler (22) for providing the inlet air to the engine at a temperature in the range of from 150 to 250 degrees Fahrenheit. The system further has one or more turbines (18, 26) for extracting energy from the exhaust gas. The Miller Cycle is implemented in the rotary engine, enabling the compression ratio to be lower than the expansion ratio, allowing the overall cycle to be optimized for lowest weight and specific fuel consumption.