Patent Application
20100172753
The present invention relates generally to compressors, and more specifically to an air inlet system for a centrifugal compressor of an air cycle machine for aircraft environmental control system or a gas turbine engine compressor.
Centrifugal compressors of air cycle machines for aircraft environmental control systems may be mounted on the mid-portion of a rotating shaft between a turbine and a fan. This configuration is commonly referred to as a three-wheel Air Cycle Machine (ACM). It is typical of an ACM that the energy gained in turbine is used to drive a compressor and a fan. All three wheels (turbine, compressor, and fan) may be disposed on a common shaft of an ACM or three-wheel machine. The fan may convey a cooling air stream branched off from ambient air through a cooling shaft in which primary and main heat exchangers may be disposed.
For three-wheel ACMs, the compressor is usually mounted on the mid-portion of the rotating shaft between the turbine and the fan; this typical configuration may result in a geometrically complicated side inlet design. The air inlet may need to first direct the flow radially inward from one side, then split the flow around the rotating shaft towards two sides, and simultaneously turn the flow into an axial direction for entry into an impeller eye of a compressor.
Since a compressor's overall performance may be sensitive to the inlet flow pattern and inlet pressure loss, various inlet plenum configurations such as a double-lobed plenum and array of inlet guide vanes (IGVs) have been used for aircraft environmental control applications. Such a configuration is shown in
As can be seen, there is a need for minimizing the inlet aerodynamic loss of an inlet plenum and promoting inlet flow uniformity while providing a means to reduce the manufacturing complexity of the plenum for an ACM.
According to one aspect of the present invention, a centrifugal compressor of an ACM for an aircraft environmental control system is provided. The compressor has a rotatable cylindrical shaft with an impeller having blades radially extending outward therefrom. An air inlet plenum has a cylindrical sidewall, a first end wall, and a second end wall. The first end wall has an aperture configured to be substantially sealed about the rotatable cylindrical shaft. The second end wall has an outlet in flow communication with the impeller about the rotatable shaft. An air inlet extends radially outward from the cylindrical sidewall and is in flow communication with the air inlet plenum. A baffle extends radially inward from the cylindrical wall approximately 180° from the air inlet.
In another aspect of the present invention, a centrifugal compressor is provided having a shaft with a longitudinal axis and a gas turbine engine configured to rotate the shaft about the longitudinal axis. The shaft has an impeller with blades extending radially therefrom. An air inlet plenum has a portion about the shaft between the gas turbine engine and the impeller. The air inlet plenum is configured to first direct the flow of inlet air radially inward to the shaft from one side of the shaft and split a portion of the flow of inlet air around the rotating shaft while simultaneously turning the flow of inlet air parallel to the longitudinal axis of said shaft for entry into the impeller. The portion of the plenum about the shaft has a cylindrical outer wall with an air inlet portion extending therefrom in a radial direction from the shaft. A rectangular baffle extends radially inward from the cylindrical outer wall of the plenum toward the shaft. The rectangular baffle is on an opposite side of the cylindrical outer wall than the air inlet portion and extends the cylindrical outer wall in a direction substantially parallel with the longitudinal axis of the shaft.
In yet another aspect of the present invention, an air inlet plenum is provided to direct air into a compressor impeller. The air inlet plenum has a cylindrical outer wall, a first circular end wall, and a second circular end wall. An air inlet radially extends from the cylindrical outer wall and is in flow communication therewith. An aperture in the first circular end wall is configured to sealing receive a rotating shaft. An aperture in the second circular end wall is configured to receive the rotating shaft and allow air flow between the second circular end wall and the rotating shaft. A rectangular baffle extends radially inward from the cylindrical outer wall at a circumference thereof opposite the air inlet. The rectangular baffle extends between the first and second end walls.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims.
The following detailed description is of the best currently contemplated modes of carrying out the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims.
Various inventive features are described below that can each be used independently of one another or in combination with other features. However, any single inventive feature may not address any of the problems discussed above or may only address one of the problems discussed above. Further, one or more of the problems discussed above may not be fully addressed by any of the features described below.
For three-wheel Air Cycle Machines (ACMs), the centrifugal compressor may be mounted on the mid-portion of a rotating shaft between a turbine and an impeller or fan. This configuration may result in a geometrically complicated side inlet design, which may be required to first direct the flow of intake air through an air inlet radially inward from one side and then split the air flow around the rotating shaft and simultaneously turn the air flow to an axial direction for entry into the impeller eye. Since compressor overall performance may be sensitive to the inlet flow pattern and inlet pressure loss, the configuration of an air plenum may be critical. Embodiments of the present invention may provide a means for enhancing the aerodynamic performance of an air delivery system to the impeller without increasing manufacturing complexity and costs.
As shown in
Plenum 102 with circular or cylindrical side wall 132 having a single rectangular baffle 130 may be casted easily and baffle 130 may prevent the flow 140 from swirling inside plenum 102 and force the flow to turn axially toward aperture 126 earlier and enter the impeller earlier and thus may promote inlet flow uniformity to the impeller and reduce the inlet pressure loss.
It should be understood, of course, that the foregoing relates to exemplary embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.
