Coolable airfoil structure

• US 5,403,159 A
• Filed: 11/30/1992
• Issued: 04/04/1995
• Est. Priority Date: 11/30/1992
• Status: Expired due to Term

• Current Assignee: Gene D. Fleischhauer
• Original Assignee: United Technologies Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Yamarik, George J., Green, Dennis J.
• Primary Examiner(s): Look, Edward K.
• Assistant Examiner(s): VERDIER, CHRISTOPHER M
• Application Number:
  US07/982,820
• Time in Patent Office: 855 Days
• Field of Search: 415/115, 415/116, 416/95, 416/96 R, 416/96 A, 416/97 R
• US Class Current: 416/97.00R
• CPC Class Codes: F01D 5/187 Convection cooling
• CPC Class Codes: F05D 2260/201 by impingement of a fluid
• CPC Class Codes: F05D 2260/202 by film cooling
• CPC Class Codes: F05D 2260/2212 by creating turbulence vortex generators, turbulators or the like for mixing F05D2240/127
• CPC Class Codes: Y02T 50/60 Efficient propulsion technologies, e.g. for aircraft

Abstract

A coolable airfoil 10 has a plurality of spanwisely extending passages. Various construction details are developed to increase the cooling effectiveness of the internal structure and decrease the need for cooling air. In one particular embodiment, a leading edge passage 56 has film cooling air flowing over the passage to shelter the passage from the hot working medium gases. This sheltered cooling air is then mixed with heated cooling air from a tortuous passage 84, 92 flowing through the mid-chord region 68 of the blade. In one embodiment, the coating air is supplied to a chordwisely extending tip passage 74 to cool the airfoil tip region and is mixed in the passage 74.

Claims

1. A coolable rotor blade for an axial flow rotary machine which comprises:

a root section which adapts the rotor blade to engage a rotor assembly, the root section having a chordwisely extending root wall, a first duct adapted to be in flow communication through the root wall with a source of cooling air, a second duct adapted to be in flow communication through the root wall with a source of cooling air and, a third duct adapted to be in flow communication through the root wall with a source of cooling air;

an airfoil section having;

a leading edge,

a trailing edge,

a suction sidewall,

a pressure sidewall joined to the suction sidewall at the leading edge and the trailing edge and spaced from the suction sidewall to form a cavity therebetween,

a tip region having a wail extending in the chordwise direction between the suction sidewall and the pressure sidewall,

a first rib which extends in the spanwise direction to the tip wall and is spaced from the leading edge to divide the cavity into a rear portion and a front portion, the front portion having a first passage in flow communication with the first duct,

a second rib which extends in the spanwise direction and is spaced chordwisely from the first rib to divide the rear portion of the cavity into a mid-chord region and into a trailing edge region which is in flow communication with the third duct, the rib extending in the chordwise direction and being spaced spanwisely from the tip wall leaving a tip passage therebetween in flow communication with the mid-chord region;

a third rib which extends in the spanwise direction from the rootwall to divide the mid-chord region of the blade into a second passage extending outwardly from the root region to the tip region and a third passage extending inwardly from the tip region to the root region, the third rib being spaced spanwisely from the chordwisely extending portion of the second rib leaving a first turning passage therebetween;

a fourth rib which extends in the spanwise direction from the chordwisely extending portion of the second rib to the root region, the fourth rib bounding the third passage and being spaced chordwisely from the first rib leaving an outwardly extending fourth passage therebetween, the fourth passage being in flow communication with the tip passage and being spaced spanwisely from the root wall leaving a second turning passage therebetween which places the fourth passage in flow communication with the third passage;

a fifth rib which extends spanwisely in the front portion of the airfoil from the tip wall to the root wall to bound the first passage, the fifth rib being spaced chordwisely from the leading edge to leave an impingement space therebetween, the fifth rib having a plurality of impingement holes extending therethrough to place the first passage in flow communication with the leading edge;

wherein a plurality of film cooling holes extend through the leading edge region from the impingement space to the exterior of the airfoil to cool the airfoil and to block the transfer of heat from the hot working medium gases to the cooling air in the first passage;

wherein the second passage is in flow communication with the second duct to supply cooling air to the second passage and such that the cooling air supplied to the second passage is flowable inwardly through the third passage and outwardly through the fourth passage to the tip passage such that the second, third and fourth passages form a continuous, tortuous passage in the mid-chord region, and,

wherein an opening extends through the first rib in the tip region to place the first passage in flow communication with the tip passage to mix the cooling air from the first passage with the cooling air from the tortuous passage in the mid-chord region.

2. The coolable rotor blade of claim 1 wherein a sixth rib is disposed spanwisely in the second passage to form sub-passages having a chordwise width W to height H ratio between sidewalls which is less than or equal to one (W/H≦

1.0) in the spanwisely extending portion of the passage.

3. The coolable rotor blade of claim 1 wherein a sixth rib extends into the first turning passage to form subpassages such that the ratio of width to height in each subpassage is less than or equal to one and a half (W/H≦

1.5) in the turning passage.

4. The coolable rotor blade of claim 2 wherein a sixth rib extends into the first turning passage to form subpassages such that the ratio of width to height in each subpassage is less than or equal to one and a half (W/H≦

1.5) in the turning passage.

5. In a coolable airfoil for a rotary machine of the type having an airfoil section which has a leading edge and a trailing edge, a root section for supplying cooling air to the airfoil section and a tip region in the airfoil section spaced spanwisely from the root section, the tip region having a spanwisely extending tip passage which has an upstream end and which has a downstream end which is in flow communication with the exterior of the blade, the improvement which comprises:

the airfoil section having

a suction sidewall and a pressure sidewall bounding a first passage for the cooling air extending outwardly to the tip region, the first passage having a length,

an impingement plate spaced spanwisely from the leading edge to leave an impingement space therebetween which extends from the root section to the tip region and which has a length, the impingement plate bounding the first passage and having impingement holes extending therethrough to place the first passage in flow communication with the impingement space and for impinging the cooling air against the leading edge,

film cooling holes extending through the airfoil sidewalls to place the impingement space in flow communication with the exterior of the blade to provide film cooling to the first passage,

a tortuous passage extending outwardly to the tip region, the tortuous passage being rearwardly of the first passage and having a length which is at least twice as long as the length of the first passage;

wherein the first passage and the tortuous passage are in flow communication with the tip passage for discharging the cooling air into the upstream end of the tip passage, wherein under operative conditions the cooling air from the first passage is at a lower temperature than the cooling air from the tortuous passage to cool the mixture of cooling air in the tip passage, and wherein the entire length of the impingement space is blocked from flow communication with the tip passage to avoid heated air from the impingement space from flowing into the tip passage.

6. The coolable airfoil of claim 5 wherein film cooling holes extend from the tip passage to the exterior of the airfoil section and wherein the downstream end of the tip passage is in flow communication with the trailing edge region of the airfoil section.