# US 8,739,508 B1 · Shock cancellation mechanism for the control of unsteady interaction in contra-rotating high- and low-pressure turbines > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,739,508 B1 - Document ID: US8739508B1 - Status: Granted - Kind: B1 - Application number: 12/569,015 - Filed: 2009-09-29 - Granted: 2014-06-03 - Earliest claimed: 2009-09-29 - Assignees: The United States of America as represented by the Secretary of the Air Force - Applicants: John P. Clark - Inventors: John P. Clark - Web page: https://patentgrep.com/patent/US8739508B1 ## CPC - F01D 5/186: {Film cooling (F01D5/187 takes precedence)} - F01D 1/26: traversed by the working-fluid substantially axially - F01D 5/142: {of the blades of successive rotor or stator blade-rows} - F01D 5/145: {Means for influencing boundary layers or secondary circulations (for compressors F04D29/68)} - F02C 3/067: having counter-rotating rotors (F02C3/073 takes precedence) - F05D 2240/123: related to the pressure side of a stator vane - F05D 2240/302: characteristics related to shock waves, transonic or supersonic flow - F05D 2250/44: by counter rotation - F05D 2260/96: Preventing, counteracting or reducing vibration or noise - F05D 2270/14: to control thermoacoustic behaviour in the combustion chambers - Y02T 50/60: Efficient propulsion technologies, e.g. for aircraft - F01D: NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES (machines or engines for liquids F03; non-positive displacement pumps F04D) - F02C: GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS (construction of turbines F01D; jet-propulsion plants F02K; construction of compressors or fans F04; generating combustion products of high pressure or high velocity F23R; using gas turbines in compression refrigeration plants F25B11/00) - F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract In a high pressure turbine used in combination with a contra-rotating low pressure turbine, in which the geometry of the inlet guide vane of the low pressure turbine induces a reflection of the incident shock wave from the high pressure turbine airfoil that propagates back upstream to impact the blade thereby denigrating both the performance of the high pressure turbine and its durability. The shock wave reflection is eliminated by fitting the downstream vanes with holes or indentations that allow jets of compressor bleed air to penetrate the boundary layer and induce a net velocity component across the main-flow direction in the near-wall region. This induced flow component acts to cancel the net flow component created by the moving shock from the upstream blade row thereby obviating the reflection that occurs naturally to cancel the flow. ## Claims ### Claim 1 A gas turbine engine, comprising; (a) high pressure turbine blades; (b) contra-rotating low pressure turbine vanes downstream from the high pressure turbine blades; (c) means for inducing a component of gas velocity, which penetrates a boundary layer along a high pressure surface of the low pressure turbine vanes equal and opposite to a velocity component of a shock wave from the high pressure turbine blades. ### Claim 2 (depends on 1) The gas turbine engine of claim 1, wherein the means for inducing a component of gas velocity comprises a series of irregularities along the high pressure surface of the vanes. ### Claim 3 (depends on 2) The gas turbine engine of claim 2, wherein the series of irregularities comprise a series of holes in the high pressure surface of the vanes. ### Claim 4 (depends on 3) The gas turbine of claim 3, wherein the holes penetrate the high pressure sides of the vanes to a hollow interior of the vanes, allowing compressor bleed air to escape the interiors of the vanes. ### Claim 5 (depends on 2) The gas turbine engine of claim 2 wherein the series of irregularities comprise a series of indentations in the high pressure surface of the vane. ### Claim 6 A gas turbine engine, comprising a high pressure turbine blade in combination with a contra-rotating low pressure turbine vane having a series of irregularities along the high pressure surface of the vane; the irregularities configured to induce a component of gas velocity, which penetrates a boundary layer along a high pressure surface of the low pressure turbine vane, equal and opposite to a velocity component of a shock wave from the high pressure turbine blade. ### Claim 7 (depends on 6) The gas turbine engine of claim 6, wherein the series of irregularities comprise a series of holes in the high pressure surface of the vane. ### Claim 8 (depends on 7) The gas turbine of claim 7, wherein the holes penetrate the high pressure side of the vane to a hollow interior of the vane. ### Claim 9 (depends on 6) The gas turbine engine of claim 6 wherein the series of irregularities comprise a series of indentations in the high pressure surface of the vane. ### Claim 10 (depends on 2) The gas turbine engine of claim 2 wherein the series of irregularities comprise a series of slots in the high pressure surface of the vane. ### Claim 11 (depends on 10) The gas turbine of claim 10 wherein the slots penetrate the high pressure side of the vane to a hollow interior of the vane allowing compressor bleed air to escape the interior of the vane.