Passage channel for a turbomachine and turbomachine

Abstract

A transition duct for a turbomachine, in particular an aircraft engine, for forming a flow channel between an upstream flow cross section and a downstream flow cross section, including supporting ribs which extend between a radially inner duct wall and a radially outer duct wall and each of which has a profile for deflecting a flow from an inlet area to an outlet area of the transition duct, the supporting ribs each having a profile variation in the area of their trailing edge and / or at least one blow-out opening for blowing out a fluid; also disclosed is a turbomachine having a transition duct of this type.

Description

[0001]This claims the benefit of European Patent Application EP 12170498.5, filed Jun. 1, 2012 and hereby incorporated by reference herein.[0002]The present invention relates to a transition duct for a turbomachine as well as a turbomachine.BACKGROUND[0003]A transition or deflecting duct in an axial turbomachine, such as an aircraft engine, conducts a main flow from an upstream flow cross section to a radially offset flow cross section. The transition duct usually has an annular cross section and is situated, for example, between a high pressure turbine and a low pressure turbine (turning mid turbine frame—TMTF). In a three-part design of a turbine, the transition duct may also be situated between a high pressure turbine and an intermediate pressure turbine as well as between the intermediate pressure turbine and a low pressure turbine. In compressors, a transition duct may similarly conduct the flow from an upstream flow cross section to a downstream flow cross section and be situa...

AI Technical Summary

Benefits of technology

[0008]It is an object of the present invention to provide a transition duct for a turbomachine which eliminates the aforementioned disadvantages and permits an improved wake mixture. A further alternate or additional object of the present invention is to provide a turbomachine which has a high degree of efficiency and a low noise development.

[0010]The profile variation and / or the at least one blow-out opening induce(s) a passive and / or active wake mixture of the outflow, resulting in a rapid calming of the flow. As a result of the early wake mixture, the inflow of rotor blades downstream from the outlet area of the transition duct is improved, so that energy transmission losses and aerodynamic excitations of the rotor blades are minimized. With the aid of the profile variation or passive wake mixture, a suction-side partial flow and a pressure-side partial flow are equalized with regard to their outflow speed, whereby eddies are reduced when the partial flows merge downstream from the trailing edge, which results in a wake flow which is calmed early on. With the aid of the at least one blow-out opening or active wake mixture, the outflow is energized by blowing in a fluid, which also improves the wake mixture. In addition, the supporting ribs are cooled by the fluid in the area of their trailing edge, which reduces their thermal load. In a combination of the passive and the active wake mixture to form a hybrid-type wake mixture, both equalization and energizing of the outflow take place.

[0013]In one exemplary embodiment of an active wake mixture, the at least one blow-out opening exits the trailing edge between the suction side and the pressure side. Due to this measure, the at least one blow-out opening is situated on the camber line of the supporting rib, and the fluid is blown in uniformly between the outflowing partial flows, thereby preventing a deflection of the suction-side or pressure-side partial flow in the circumferential direction.

[0019]At least one flow splitter blade may be situated between the supporting ribs, which has a smaller relative profile thickness than the supporting ribs. The at least one flow splitter blade is based on the finding that eddies, flow losses and / or deflection limitations may be reduced if additional deflecting elements are situated between the supporting ribs which are also profiled to deflect the flow, these deflecting elements being designed as narrower and / or shorter flow splitters compared to the supporting ribs.

[0021]A preferred turbomachine has a transition duct according to the present invention. This transition duct produces an improved inflow from rotor blades downstream from the outlet area of the transition duct, due to the rapid wake mixture. The improved inflow results in minimized energy transmission losses and thus in a high degree of efficiency as well as in a minimized aerodynamic excitation of the downstream rotor blades and thus a noise reduction compared to turbomachines having a conventional transition duct. The transition duct is preferably situated on the turbine side but may also be situated on the compressor side.

Problems solved by technology

However, such a geometry of the supporting ribs results in heavy secondary flows.

In particular, they may limit a maximum possible deflection on the hub and housing and result in energy transmission losses.

In addition, secondary flows may result in excitations of the first moving blade row of the downstream turbine and thus in high noise development.

Moreover, the number of blades of the transition ducts, which is much smaller compared to conventional stator geometries, may cause aerodynamic excitations of the subsequent rotor blades having fundamental modes, so-called engine orders, in the working area of the turbomachine.

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