Exhaust Diffuser Flaring Geometry for Pressure Loss Reduction
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Solution Overview
Problem
Conventional exhaust diffusers with tubular struts experience significant pressure loss due to the thick, tubular struts, particularly at their leading and trailing edges.
Innovation Solution
The exhaust diffuser design incorporates tubular struts coupled with external and internal cylinders, featuring a front conical and outer flaring portion on the external cylinder and a front straight and inner flaring portion on the internal cylinder, which reduces pressure loss by expanding the exhaust passage before and after the tubular struts, and includes flattened struts to gradually change the cross-sectional area, stabilizing the flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If tubular struts are used to couple internal and external cylinders, then structural strength is improved, but pressure loss increases due to thick strut walls
Solution Approach 1:
The outer flaring portion expands the exhaust passage cross-sectional area before the exhaust gas reaches the tubular struts, preliminarily reducing the gas velocity and kinetic energy. This preliminary action ensures that when the gas flows past the struts, the velocity is already sufficiently reduced, minimizing pressure loss while maintaining structural integrity
Solution Approach 2:
The invention addresses the pressure loss problem not by thinning the struts (one-dimensional solution) but by expanding the passage area in the radial dimension through flaring portions. This dimensional approach allows maintaining thick struts for strength while compensating for their obstructive effect through increased passage area
2Productivity
If the exhaust passage cross-sectional area suddenly increases after tubular struts, then flow expansion is achieved, but pressure loss increases due to sudden area change
Solution Approach 1:
The inner flaring portion preliminarily expands the exhaust passage area before the gas reaches the region where the struts end. This gradual preliminary expansion prevents sudden area changes, reducing turbulence and pressure loss while still achieving the necessary flow expansion for productivity
Solution Approach 2:
The flaring portions use curved, gradual expansion geometry rather than sudden angular changes. This curved transition smooths the flow expansion process, reducing eddies and turbulence that would cause pressure loss, while still achieving the required cross-sectional area increase
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 effectively reduces pressure loss near the tubular struts' edges and overall, making it suitable for middle-size and small-size gas turbine engines by minimizing the sudden increase in cross-sectional area and stabilizing exhaust gas flow.
Implementation Method 1
an exhaust diffuser that converts the dynamic pressure of exhaust gas from a turbine into static pressure
Data Source
AI summary
An exhaust diffuser includes: an internal cylinder; an external cylinder that forms an exhaust passage between the internal cylinder and the external cylinder, the exhaust passage expanding from front to rear; and at least one tubular strut that couples the internal cylinder and the external cylinder together. The external cylinder includes: a front conical portion that is positioned forward of the tubular strut; and an outer flaring portion that starts flaring at a positon forward of the tubular strut at an inclination angle that is greater than an inclination angle of the front conical portion. The internal cylinder includes: a front straight portion that faces the front conical portion and the outer flaring portion; and an inner flaring portion that starts flaring at a position between a maximum width portion and a trailing edge of the tubular strut.