Movable Heat-Conductive Elements in Turbofan Heat Exchangers
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Solution Overview
Problem
Heat exchangers in turboshaft engines cause pressure losses in the secondary air flow, which negatively impact engine performance, as the cooling requirements do not always align with high-performance flight phases.
Innovation Solution
A heat exchanger with movable heat-conductive elements, such as blades, that can transition between active and inactive positions by buckling of a membrane, reducing flow resistance and heat exchange exposure when cooling is less critical.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If heat exchangers are arranged in the secondary flow path to cool fluids circulating in the engine, then heat exchange capacity is improved, but pressure losses in the flow increase
Solution Approach 1:
The heat-conductive elements are made movable between active and inactive positions through the buckling mechanism of the membrane. This dynamic configuration allows the system to adjust its heat exchange capacity and flow resistance characteristics based on operational requirements, resolving the contradiction between cooling capacity and pressure losses.
Solution Approach 2:
The membrane's mechanical state (flat vs. buckled) changes the exposure parameter of the heat-conductive elements to the fluid flow. By controlling the membrane's deformation state, the system can switch between high heat exchange capacity (exposed elements) and low pressure loss (retracted elements), addressing the technical contradiction.
2Temperature
If heat exchangers are used during cruising flight phases, then cooling is provided, but pressure losses adversely affect engine performance
Solution Approach 1:
The system dynamically adjusts the heat exchanger configuration based on flight phase requirements. During cruising phases with lower cooling demands, the membrane buckles to retract heat-conductive elements, minimizing their impact on flow characteristics and preserving engine performance while still providing necessary cooling when required.
Solution Approach 2:
The exposure parameter of heat-conductive elements is changed by controlling the membrane's buckling state. This allows the system to optimize the balance between cooling provision and flow resistance characteristics according to the specific operational phase, maintaining engine performance during cruising while meeting cooling requirements.
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 solution effectively controls heat exchange and reduces pressure losses by modifying the exposure of heat-conductive elements to the fluid, allowing for efficient cooling during high-demand phases while minimizing flow resistance during low-demand phases.
Implementation Method 1
a membrane separating the two fluids and a heat-conductive element in thermal contact with both the membrane and the first fluid
Implementation Method 2
a heat-conductive element in thermal contact with both the membrane and the first fluid
Implementation Method 3
the transition from the active position to the inactive position is achieved by buckling of the membrane
Data Source
AI summary
The invention relates to a heat exchanger (10) for heat-exchange between a first fluid and a second fluid, comprising a membrane separating the two fluids and a heat-conductive element (17) in thermal contact with the membrane and with the first fluid, characterised in that said heat-conductive element (17) moves between an active position and an inactive position, such that the capacity of heat exchange with the first fluid is weaker in the inactive position than in the active position. The exchanger is applied, in particular, for the cooling of fluid in the secondary stream of a turbofan.