Series-Parallel Fuel Metering System Pressure Regulation
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Solution Overview
Problem
Existing parallel metering systems in combustion engines require over-sizing of pumps and maintain high discharge pressure, leading to unnecessary heat input and inefficiency, which is not suitable for aircraft engine operations.
Innovation Solution
A series plus parallel metering system with a single bypassing metering system and a primary regulated circuit in parallel with secondary metering circuits, where a parallel pressure regulator ensures sufficient pressure and a bypass regulator adjusts pump discharge pressure to match system demands, reducing excess pressure and heat input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the pump discharge pressure is maintained at high pressure to meet the pressure needs of metered flow paths for all operating conditions, then the pressure requirements of the system are satisfied, but the pump heat input to the fuel system increases undesirably
Solution Approach 1:
The system dynamically adjusts pump discharge pressure based on real-time flow demands of the metered flow paths. The pressure regulation system modifies the pressure setting according to operating conditions, allowing the pump to operate at lower pressures when full pressure is not required, thereby reducing pump heat input while still meeting system pressure needs.
Solution Approach 2:
The invention changes the pressure parameter dynamically rather than maintaining a constant high pressure. By adjusting the pressure setting of the positive displacement pump according to the actual flow demands of different operating conditions, the system reduces unnecessary heat input while ensuring sufficient pressure is always available when needed.
2Adaptability or versatility
If the pump is oversized to accommodate various systemic pressure demands, then the system can meet all pressure requirements, but the pump size and complexity increase
Solution Approach 1:
Instead of using an oversized pump to handle all pressure demands, the system employs a dynamically adjustable pressure regulation mechanism on a properly sized pump. This allows the same pump to effectively handle varying pressure demands by changing its operating pressure setting, thereby avoiding the need for pump oversizing and reducing overall system complexity.
3Device complexity
If a single high-pressure pump is used to supply all metered flow paths, then the system structure is simplified, but the thermal efficiency decreases due to excessive heat input
Solution Approach 1:
The invention maintains the simplified single-pump structure but adds dynamic pressure regulation capability. The pressure regulation system allows the pump to operate at optimally low pressures for each operating condition, significantly reducing pump heat input and improving thermal efficiency while preserving the benefits of a simple single-pump architecture.
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
This configuration optimizes fuel flow management by maintaining sufficient pressure while minimizing pump size and heat input, enhancing thermal efficiency and flexibility in meeting varying operational demands.
Implementation Method 1
Positive displacement pumps are often preferred for turbine engines due to their good efficiency and high reliability
Implementation Method 2
The single bypassing fuel metering system regulates the pump discharge pressure to a sufficient pressure to supply the metering and combustion systems by the bypassing positive displacement pump flow in excesses of the system flow demand back to the low pressure inlet of the pump
Implementation Method 3
A parallel pressure regulator in the primary regulated circuit of the parallel metering system is referenced to each secondary metering circuit and acts to ensure that sufficient pressure is maintained to supply each secondary metering circuit
Implementation Method 4
The single bypassing metering system upstream of the parallel system meters total fuel flow that is sent to the parallel metering system
Data Source
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AI summary
An engine fuel system and methods are provided. The engine fuel system includes a supply arrangement for providing an outlet flow of fuel to a bypass metering arrangement. The bypass metering arrangement in turn provides a metered flow of fuel to a parallel metering system including a primary regulated circuit and one or more secondary metering circuits. The bypass metering arrangement is operable to maintain a substantially constant pressure differential across a fuel metering valve thereof, as well as provide the metered flow of fuel in response to downstream pressure demands of the parallel metering system.