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  Leading edge cooling using wrapped staggered-chevron trip stripsUSPTO Application #: 20070297916Title: Leading edge cooling using wrapped staggered-chevron trip strips Abstract: A turbine engine component has an airfoil portion having a leading edge, a suction side, and a pressure side and a radial flow leading edge cavity through which a cooling fluid flows for cooling the leading edge. The turbine engine component further has a staggered arrangement of trip strips for generating a vortex in the leading edge cavity which impinges on a nose portion of the leading edge cavity. (end of abstract)
Agent: Bachman & Lapointe, P.C. (p&w) - New Haven, CT, US Inventors: Jeffrey R. Levine, William Abdel-Messeh, Eleanor Kaufman USPTO Applicaton #: 20070297916 - Class: 416 96 R (USPTO) The Patent Description & Claims data below is from USPTO Patent Application 20070297916. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND [0001](1) Field of the Invention [0002]The present invention relates to enhanced cooling of the leading edge of airfoil portions of turbine engine components using trip strips that are staggered and wrapped around the nose of the leading edge cavity. [0003](2) Prior Art [0004]Due to the extreme environment in which they are used, some turbine engine components, such as blades and vanes, are cooled. A variety of different cooling techniques have been employed. One such scheme is illustrated in FIG. 1 where there is shown an airfoil portion 10 of a turbine engine component 12. As can be seen from the figure, a radial flow leading edge cavity 14 is used to effect cooling of the leading edge region. [0005]Despite the existence of such a cooling scheme, there remains a need for improving the cooling of the leading edge of the airfoil portions of turbine engine components. SUMMARY OF THE INVENTION [0006]Accordingly, it is an aim of the present invention to provide enhanced cooling for the leading edge of airfoil portions of turbine engine components. [0007]In accordance with the present invention, a turbine engine component broadly comprises an airfoil portion having a leading edge, a suction side, and a pressure side, a radial flow leading edge cavity through which a cooling fluid flows for cooling the leading edge, and means for generating a vortex in the leading edge cavity which impinges on a nose portion of the leading edge cavity. The vortex generating means comprises a first set of trip strips which wrap around the nose portion of the leading edge cavity and a second set of trip strips. The first set of trip strips is staggered relative to the second set of trip strips. [0008]Other details of the leading edge cooling using staggered trip strips of the present invention, as well as other objects and advantages attendant thereto, are set forth in the following detailed description and the accompanying drawings wherein like reference numerals depict like elements. BRIEF DESCRIPTION OF THE DRAWINGS [0009]FIG. 1 illustrates a prior art turbine engine component having a radial flow leading edge cavity; [0010]FIG. 2 illustrates a cross-section of a leading edge portion of an airfoil used in a turbine engine component having staggered and wrapped trip strips; [0011]FIG. 3 illustrates the trip strips on the suction side of the leading edge portion; [0012]FIG. 4 illustrates the trip strips on the pressure side of the leading edge portion; [0013]FIG. 5 illustrates the placement of the leading edge of the staggered trip strips; [0014]FIG. 6 is a three dimensional view of the leading edge trip strips; and [0015]FIG. 7 illustrates the vortex generated in the leading edge cavity. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) [0016]Referring now to the drawings, FIG. 2 illustrates the leading edge 30 of an airfoil portion 32 of a turbine engine component. As can be seen from this figure, the leading edge 30 has a leading edge cavity 34 in which a cooling fluid, such as engine bleed air, flows in a radial direction. The leading edge 30 also has a nose portion 36 and an external stagnation region 38. [0017]It has been found that trip strips are desirable to provide adequate cooling of the leading edge, especially at the nose portion 36 of the airfoil portion 32 adjacent to the external stagnation region 38. The trip strip arrangement which will be discussed hereinafter provides high heat transfer to the leading edge 30 of the airfoil portion 32. [0018]As shown in FIGS. 2, 5 and 6, a plurality of trip strips 40 are positioned on the pressure side 42 of the airfoil portion 32, while, as shown in FIGS. 2, 3, and 6, a plurality of trip strips 44 are placed on the suction side 46 of the airfoil portion 32. Referring now to FIGS. 2 and 6, the trip strips 40 on the pressure side 42 are wrapped around the leading edge nose portion 36. As the pressure side trip strips 40 wrap around the leading edge, the curvature of the leading edge nose portion 36 causes the trip strips 40 to be oriented more or less normal to the direction of flow 48 (see FIG. 6). As cooling air passes over the thus oriented trip strips 40, the flow is tripped and generates a large vortex 49 at the leading edge (see FIG. 7). This large vortex generates very high heat transfer coefficients at the leading edge nose 36. [0019]Referring now to FIGS. 4 and 6, it can be seen that the trip strips 40 and the trip strips 44 are preferably staggered approximately one half pitch apart between the suction side 46 and the pressure side 42 of the airfoil portion 32. As shown in FIGS. 2 and 7, there is also a gap 47 between adjacent ones of the trip strips 40 and the trip strips 44. Each gap 47 is preferably located along a parting line 70 of the airfoil portion 32. [0020]The orientation of the trip strips 40 and 44 in the cavity 34 also increases heat transfer at the leading edge 30 of the airfoil portion 32. If desired, the trip strips 40 and 44 may be oriented at an angle .alpha. of approximately 45 degrees relative to the flow direction 48. The leading edges 54 and 56 of the trip strips 40 and 44 are positioned in the region of highest heat load, in this case the leading edge nose 36. This trip strip orientation permits the creation of a turbulent vortex 49 in the cavity 34. The cooling fluid initially hits the leading edges 54 and 56 of the trip strip and separates from the airfoil surface. The flow then re-attaches downstream of the trip strip leading edges 54 and 56 and moves toward the divider rib 60 between the leading edge cavity 34 and the adjacent cavity 62. As the flow approaches the divider rib 60, it is forced toward the opposite airfoil wall. The flow is directed perpendicular to the pressure side and suction side walls 42 and 46, and meets at the center of the cavity 34. The flow is now forced back towards the leading edge 30 of the airfoil portion 32. The result of this flow migration causes a large vortex 49 that drives flow into the leading edge of the cavity, acting as an impingement jet which also enhances heat transfer at the leading edge nose 36. Continue reading... Full patent description for Leading edge cooling using wrapped staggered-chevron trip strips Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Leading edge cooling using wrapped staggered-chevron trip strips patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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