Gas Turbine Ejector Closure Sectors Prevent Backflow
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Solution Overview
Problem
In gas turbines, backflow of hot primary air through the peripheral opening between the exhaust pipe and ejector occurs at certain engine speeds and flight conditions, leading to inadequate cooling of the engine bay and equipment, and existing solutions do not effectively prevent this backflow across all speeds, especially when the ejector is bent.
Innovation Solution
The peripheral opening between the pipe and ejector is partially closed over specific angular sectors determined by interactions between secondary and primary flows, air gyration, and geometries, using methods like bonding or welding of composite materials to prevent reingestion of primary flow, with closure sectors extending between 30° to 270° and avoiding attachment tabs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the peripheral opening between the pipe and ejector is left open to allow secondary flows to cool the engine bay, then cooling effectiveness is improved, but hot primary air backflow into the engine bay occurs at certain engine speeds and flight conditions
Solution Approach 1:
The peripheral opening is segmented into open sectors and closed sectors, where closed sectors prevent hot primary air backflow while open sectors allow secondary flows to cool the engine bay. This segmentation resolves the contradiction by spatially separating the cooling function from the backflow prevention function.
Solution Approach 2:
Different regions of the peripheral opening have different properties: some regions (closed sectors) are sealed to prevent backflow, while other regions (open sectors) remain open for cooling. This local differentiation allows the system to simultaneously achieve backflow prevention and effective cooling.
2Object-affected harmful factors
If the peripheral opening is partially closed to prevent backflow, then hot primary air reingestion is prevented, but cooling of the engine bay and equipment may be reduced
Solution Approach 1:
The peripheral opening is divided into multiple sectors with different functions. Closed sectors (extending at least 30°) prevent backflow, while open sectors maintain cooling airflow. This segmentation ensures that backflow prevention does not completely block the cooling function.
Solution Approach 2:
Instead of completely closing the peripheral opening to prevent backflow, only sufficient portions (closed sectors of at least 30°) are closed to achieve backflow prevention while leaving other portions open for cooling. This partial action resolves the contradiction by applying just enough closure to prevent harm while maintaining useful function.
3Object-affected harmful factors
If conventional means are used to straighten the flow through the peripheral opening, then backflow is reduced, but the solution does not guarantee results at all engine speeds and is difficult to install when the ejector is bent
Solution Approach 1:
Rather than using complex flow straightening means that are difficult to install on bent ejectors, the solution segments the peripheral opening into closed and open sectors. This simpler segmentation approach is easier to manufacture and install while effectively preventing backflow across all engine speeds.
Solution Approach 2:
The invention extracts the essential function of backflow prevention from complex flow straightening means and implements it through simpler sector closure. This extraction provides a more universally applicable solution that works at all engine speeds and is easier to manufacture and install.
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 solution effectively prevents backflow of hot primary air, ensuring consistent cooling of the engine bay and equipment across various engine speeds and flight conditions, even when the ejector is bent, by optimizing the geometry and position of the closure sectors based on flow interactions and geometries.
Implementation Method 1
The secondary flows Fs are generated by the driving effect of the hot primary flow Fp exiting from the pipe 2 around the cone 4
Implementation Method 2
The secondary flows Fs are generated by the driving effect of the hot primary flow Fp exiting from the pipe 2 around the cone 4 and also by the effect of negative pressure generated by the shape of the ejector 3
Implementation Method 3
said peripheral opening is then closed over the angular sector(s) identified in this way
Data Source
AI summary
A method for discharging exhaust gas from a gas turbine wherein a number of sectors, position, and angle at the center of at least one sector of a peripheral opening capable of forming an area for reingestion of a primary flow into an engine bay are determined by correlation of interactions between secondary cooling flows and the primary flow, from following behavior parameters: air gyration and speed at an inlet of a pipe, geometry of an exhaust stream, routing of the secondary cooling flow for cooling the engine bay, and a geometry and position of inlets of the secondary flows. The peripheral opening is then closed over the identified at least one angular sector. The method prevents backflow of hot primary air into the peripheral opening formed between a pipe and an ejector of the exhaust stream of a gas turbine.