Turbine airfoil clocking

Abstract

An assembly of airfoils in a compressor of a turbine engine that includes at least three axially stacked rows of airfoils: a middle airfoil row, a first upstream airfoil row, and a first downstream airfoil row. The middle airfoil row may be bordered on each side by the first upstream airfoil row, which comprises the first row of airfoils in the upstream direction from the middle airfoil row, and the first downstream airfoil row, which comprises the first row of airfoils in the downstream direction from the middle airfoil row. The first upstream airfoil row and the first downstream airfoil row may have substantially the same number of similarly shaped airfoils. The first upstream airfoil row and the first downstream airfoil row each may comprise a row of rotor blades, which rotate at substantially the same speed during operation. The middle airfoil row may comprise a row of stator blades, which remains substantially stationary during operation. At least 90% of the airfoils of the first upstream airfoil row and at least 90% of the airfoils of the first downstream airfoil row may comprise a clocking relationship of between 25% and 75% pitch.

Description

BACKGROUND OF THE INVENTION[0001]This present application relates to turbine engines. More specifically, but not by way of limitation, the present application relates to the positioning of airfoils in one row with respect to airfoils in neighboring or nearby rows such that certain operational benefits are achieved.[0002]A gas turbine engine typically includes a compressor, a combustor, and a turbine. The compressor and turbine generally include rows of airfoils or blades that are axially stacked in stages. Each stage generally includes a row of circumferentially spaced stator blades, which are fixed, and a set of circumferentially spaced rotor blades, that rotate about a central axis or shaft. Generally, in operation, the rotor blades in the compressor rotor rotate about the shaft to compress a flow of air. The supply of compressed air is used in the combustor to combust a supply of fuel. The resulting flow of hot gases from the combustion is expanded through the turbine, which caus...

AI Technical Summary

Benefits of technology

"The patent describes an assembly of airfoils in a compressor of a turbine engine that includes at least three axially stacked rows of airfoils. The first and second rows of airfoils are made up of rotor blades that rotate at the same speed during operation. The middle row of airfoils is made up of stator blades that remain stationary during operation. The airfoils in the first and second rows have a clocking relationship of between 25% and 75% pitch, while the airfoils in the middle row have a clocking relationship of between 25% and 75% pitch. The patent also describes a method of operating a turbine engine that includes the steps of configuring the airfoils in the first and second rows of rotor blades with a clocking relationship of between 25% and 75% pitch, and configuring the airfoils in the second and third rows of rotor blades with a clocking relationship of between 25% and 75% pitch. The technical effect of this design is improved performance and efficiency of the turbine engine."

Problems solved by technology

However, while only minimally or negligibly improving engine aero-efficiency, it has been discovered that such conventional clocking methods generally function to increase the mechanical stresses acting on airfoils during operation.

Of course, increased operational stresses can cause blade failures, which may result in extensive damage to the gas turbine engine.

At the very least, increased operational stresses shorten the part life of the airfoils, which increases to the cost of operating the engine.

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