Patent Application
20090297339
The present invention relates to the art of ejectors and, more particularly, to a low noise ejector for a turbomachine.
At least some known ejectors mix two flow streams, a high-pressure primary or motive stream and a low-pressure secondary or suction stream, to produce a discharge flow with pressure intermediate to or lower than the two input flows. The ejector nozzle facilitates this mixing process by accelerating the high-pressure motive flow creating a high speed jet. The high speed jet is channeled through a mixing tube or chamber to entrain the low-pressure suction flow. The two mixed flows are then discharged, typically through a diffuser.
The motive flow is throttled to match ejector output to a turbine operating at off-design load and/or ambient conditions. Existing throttling devices maintain a constant high speed jet diameter as output is reduced. In such devices, flow is reduced by lowering an effective velocity of the motive flow. Reducing velocity of the motive flow in a throttled condition inhibits entrainment of the ejector and thus limits an overall throttling range and degrades entrainment performance.
In accordance with one exemplary embodiment of the invention a turbomachine includes a compressor and an ejector. The ejector includes at least one nozzle having a first end portion that extends to a second end portion defining a flow region. The second end portion includes a variable outlet for controlling an airflow from the compressor.
In accordance with another exemplary embodiment of the invention, an ejector for a turbomachine includes at least one nozzle having a first end portion that extends to a second end portion defining a flow region. The second end portion includes a variable outlet configured to controlling an airflow from a compressor.
In accordance with yet another exemplarily embodiment of the invention, a method of controlling an airflow through an ejector for a turbomachine includes generating an airflow in a compressor portion of the turbomachine, guiding the airflow to an ejector, passing the airflow to a nozzle of the ejector, and passing the airflow through a variable outlet portion of the nozzle.
Additional features and advantages are realized through the techniques of exemplary embodiments of the present invention. Other embodiments and aspects of the invention are described in detail herein and are considered a part of the claimed invention. For a better understanding of the invention with advantages and features thereof, refer to the description and to the drawings.
With initial reference to
Towards that end, cooling system 30 includes a first cooling circuit 40 that interconnects compressor stage 7 with turbine stage 19. In the embodiment shown, compressor stage 7 is a mid-pressure stage that is connected to a corresponding mid-pressure stage 19 of turbine 12. Cooling system 30 also includes a second cooling circuit 44 that interconnects compressor stage 8 with turbine stage 18. Compressor stage 8 is at a higher pressure than stage 7 and thus in connected to stage 18, which, likewise, is at a pressure higher than stage 17. In addition, cooling system 30 is shown to include a bypass circuit 47 having a bypass valve 48 that is selectively operated to maintain internal pressure within turbine engine 2.
In order to utilize as little high-pressure air from compressor 4 as possible, second cooling circuit 44 is provided with an ejector 55 that is operatively connected to first cooling circuit 40 via a connector circuit 58. With this arrangement, a high pressure primary or motive airflow passing through ejector 55 draws in a portion of a lower pressure secondary or suction airflow from first cooling circuit 58. The high-pressure airflow and low-pressure airflow mix to form a combined airflow that is directed through a primary or motive nozzle 60 located within ejector 55. Motive nozzle 60 accelerates the high pressure fluid to a higher speed to substantially match a pressure and speed of fluid within, for example, turbine stage 18. However, as pressure within turbine stage 18 varies over an operating range of turbine 12, ejector 55, as will be discussed more fully below, is selectively adjustable in order to control pressures within second cooling circuit 44 to match pressures within turbine stage 18 over a wide operating range of turbine 12.
Reference will now be made to
In further accordance with the exemplary embodiment shown, ejector 55 includes a secondary motive nozzle 88 arranged within motive nozzle 60. Secondary motive nozzle 88 is operatively connected to an actuator shaft 91 through a plurality of struts, one of which is indicated at 93. As will be discussed more fully below, actuator shaft 91 is selectively operated in order to shift secondary motive nozzle 88 within flow region 75 in order to control an overall output from ejector 55. Towards that end, secondary nozzle 88 includes a first end portion 97 that extends to a second end portion 98 through an intermediate portion 99. Intermediate portion 99 defines a secondary chevron 104 that correspondingly defines a second dimension for variable outlet 78.
With this arrangement, during base load operation of turbine 2, secondary motive nozzle 88 is shifted to a first configuration as indicated in
Reference will now be made to
In order to control the selective movement of chevrons 136, nozzle 120 is provided with a chevron collar 154 that is slidingly mounted to motive pipe 124. Chevron collar 154 includes a first end 157 that extends to a second end 158. Second end 158 is operatively connected to first end section 138 of the plurality of chevrons 136. First end section 157 is operatively connected to an actuator rod 161 that is selectively shiftable in order to move or position chevrons 136 between the first position illustrated in
During normal or baseload operation of turbine 2, actuator rod 161 is shifted so as to cause chevron collar 154 to move chevrons 136 to the first configuration illustrated in
At this point, it should be appreciated that ejector 55 in accordance with provides a selectively variable airflow output thus enabling cooling circuit flow to be tailored to pressure conditions within turbine section of a turbine engine across wide operating ranges. That is, the ejector, in accordance with the exemplary embodiment of the invention, is more tunable across a broader range or operating conditions so as to provide more control at hotter temperatures and additional adjustments to provide cooling air across a wider operating range. It should also be understood that the variable outlet can be formed using a variety of different structures.
In general, this written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of exemplary embodiments of the present invention if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.
