Vortex Generators for Turbine Exhaust Backpressure Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing exhaust duct designs for turboshaft engines in rotary-wing aircraft lead to high backpressure and inefficient engine performance due to separation and inadequate diffusion of exhaust air, and the mixing with secondary cooling airflow can result in degraded performance and component loss.
Innovation Solution
The implementation of a vortex generator within the exhaust system, positioned to interrupt both primary and secondary flows, which creates vortices to enhance mixing and reduce backpressure by optimizing the diffusion process between the two flows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If existing exhaust duct designs with large turning angles are used, then the exhaust duct can accommodate the engine outlet geometry, but airflow separation occurs causing high backpressure and reduced engine efficiency
Solution Approach 1:
Vortex generators are installed upstream in the exhaust duct to pre-condition the airflow before it encounters the large turning angles. The vortex generators create controlled vortices that energize the boundary layer and prevent flow separation at the duct turns, allowing the exhaust duct to maintain its necessary geometry without suffering from airflow separation losses
Solution Approach 2:
The vortex generators modify the flow parameters by creating rotational motion and enhancing mixing in the exhaust stream. This changes the velocity profile and turbulence characteristics of the flow, enabling it to better withstand the adverse pressure gradients created by the large turning angles in the exhaust duct
2Productivity
If vortex generators are added to the exhaust system, then mixing of primary and secondary flows is enhanced and backpressure is reduced, but device complexity increases
Solution Approach 1:
The vortex generators are designed to be passive components that utilize the existing exhaust flow itself to generate the required vortices. The high-speed primary exhaust flow automatically passes over the vortex generator surfaces, creating the necessary rotational flow patterns without requiring additional energy input or active control systems
Solution Approach 2:
The vortex generators are designed with specific geometric parameters (size, shape, orientation, spacing) that are optimized to produce the desired flow conditioning effect. By carefully selecting these parameters, the system achieves effective flow mixing and separation prevention with minimal additional complexity
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 vortex generator improves engine performance by reducing exhaust losses and backpressure, enhancing the mixing of primary and secondary flows, and preventing hot exhaust backflow into the engine compartment, thus maintaining efficient engine operation and component integrity.
Implementation Method 1
a vortex generator arranged within the exhaust system at a position where both the primary flow and the secondary flow are present. The vortex generator interrupts at least one of the primary flow and the secondary flow.
Implementation Method 2
The vortex generator interrupts at least one of the primary flow and the secondary flow... creates vortices to enhance mixing
Data Source
AI summary
An exhaust system for an engine includes an exhaust nozzle located adjacent an outlet end of the engine to receive a primary flow of exhaust gasses expelled from the engine, an inlet opening formed between the exhaust nozzle and the outlet end of the engine through which a secondary flow is provided to the exhaust nozzle, and a vortex generator arranged within the exhaust system at a position where both the primary flow and the secondary flow are present. The vortex generator interrupts at least one of the primary flow and the secondary flow.