Apparatus for acoustic damping and operational control of damping, cooling, and emissions in a gas turbine engine

Abstract

Acoustic damping resonators (60, 62, 76, 78) formed in pockets (32) between reinforcing ribs (30) in a grid of ribs on the outer surface of a wall (74) surrounding a combustion gas flow path (18). Each resonator has a perforated cover plate (64A-C) spanning between sides formed by the ribs (30). Film cooling exit holes (44) are provided in the wall (74) under each resonator. Resonating chambers (48A-C) of different volumes may be provided on the wall to damp different unwanted frequencies. Different sets of resonators with different volumes may be separately controlled by respective airflow control manifolds (66) via throttle valves (68, T1-T3). Control logic (70) may control the valves based on frequency / airflow response functions (80, 82) for each size of resonator to optimize damping and cooling and to lower emissions over varying engine operating conditions.

Description

FIELD OF THE INVENTION[0001]The invention relates to an apparatus for acoustic damping of a range of acoustic frequencies, and for operational control that optimizes acoustic damping, cooling, and emission control in a combustion section of a gas turbine engine.BACKGROUND OF THE INVENTION[0002]Gas turbine engines often use a portion of air from the compressor for cooling and emissions control. Combustion gas temperatures can approach or exceed limits for structures in the working gas flow path. Therefore, cooling of surfaces adjacent the combustion gas (“hot surface”) may be implemented. Film / effusion cooling holes are provided through walls of flow-directing structures lining the working gas flow path so that a portion of the compressed air bypasses the combustor inlets and flows through these walls. This approach is used on such structures as the combustion chamber liner, transition ducts, transition exit pieces, and other components. The holes provide film cooling and effusion co...

AI Technical Summary

Benefits of technology

The invention is about an apparatus for acoustic damping of a range of acoustic frequencies in gas turbine engines. The apparatus includes a transition duct and exit pieces that direct the flow of combustion gas. The invention optimizes cooling and emission control in these areas by providing film cooling and effusion cooling holes in the duct walls. The invention also includes acoustic damping resonators that are designed to damp vibrations during operation. The resonators are attached to the duct walls and provide a cooling film on the hot inner surface of the duct walls. The invention addresses the need for improved cooling and damping in these areas, which can improve the performance and durability of gas turbine engines.

Problems solved by technology

It is so great that film cooling can overshoot and separate from the hot inner surface of the duct, reducing cooling effectiveness, unless the cooling holes are kept smaller than in prior designs and smaller than is ideal.

Smaller holes clog with particles more quickly.

Space limitations can limit the size of damping resonators, thus limiting them to damping high frequencies only, such as over 1000 Hz.

But unwanted intermediate frequencies between 50-1000 Hz are generated in gas turbine engines under some conditions.

This exposes their enclosure attachment welds to high temperatures via heat conduction through the flow path wall, which can be a design-limiting factor.

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