Spatial evolution mechanism of vortex structure in the highly-loaded helium compressor cascade

ABSTRACTThe highly-loaded design method of helium compressors can effectively solve the difficulty in compressing helium in High Temperature Gas-cooled Reactors (HTGR). But it also causes obviously different attack angle characteristics of blade surface loads in a highly-loaded helium compressor compared to air compressors. This difference inevitably affects separation characteristics and flow loss within the compressor. In the current study, the effects of highly-loaded design methods and changes in attack angle on the separation characteristics of the compressor cascade are analyzed by applying a numerical simulation method firstly. Then the influence of Mach number on the loss characteristics of the cascade for a highly-loaded helium compressor is systematically analyzed. Finally, the effect of differences in the material properties of working fluid on the separation characteristics is discussed. The results indicate that the proportion of secondary flow loss to the total loss in highly-loaded compressor cascades is 2.46 times larger than that in conventionally-loaded ones. While properties of working fluid have an effect on the performance of the compressor cascade, their effects on the weight factor of vortex loss are highly limited.KEYWORDS: Helium compressorHigh temperature gas-cooled reactor (HTGR)HTGR type reactorhighly-loaded design methodSecondary flow lossTurbineClosed Brayton cycleSpecific heat ratioComputational fluid dynamicsDisclaimerAs a service to authors and researchers we are providing this version of an accepted manuscript (AM). Copyediting, typesetting, and review of the resulting proofs will be undertaken on this manuscript before final publication of the Version of Record (VoR). During production and pre-press, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal relate to these versions also. AcknowledgementThe present work is financially supported by the National Natural Science Foundation of China (No. 52206042), Natural Science Foundation of Liaoning Province (No. 2022-BS-096), Basic Research Project of Liaoning Provincial Department of Education(LJKMZ20220364).NomenclatureTableDisplay TableDeclaration of interest statementNo potential conflict of interest was reported by the author(s).Figure 1 Construction of highly-loaded helium compressor velocity triangleDisplay full sizeFigure 2 Schematic diagram of the geometric parameters of cascadesDisplay full sizeFigure 3 Schematic diagram of S3 sectional positionDisplay full sizeFigure 4 Schematic diagram of the calculation meshDisplay full sizeFigure 5 Axial vorticity diagrams for different grid numbers of exit sectionsDisplay full sizeFigure 6 Validation of numerical simulation methodDisplay full sizeFigure 7 Variation of total loss coefficients and pressure ratios with attack angle for helium compressor cascades of different design methodsDisplay full sizeFigure 8 Static pressure curves of blade surface with 50% blade height for different design methods (Ma=0.3)Display full sizeFigure 9 Programs of limiting streamlines and static pressure coefficients of cascade with different design methodsDisplay full sizeFigure 10 Diagrams of vortex structure of helium compressor cascades S3 sections with different design methods (Ma=0.3, i= 0°)Display full sizeFigure 11 Vortex loss weights of S3 sections of helium compressor cascades with different design methods (Ma=0.3, i= 0°)Display full sizeFigure 12 Diagrams of limit streamlines and static pressure coefficients at different angles of attack on the suction surface of a highly-loaded helium compressor cascadeDisplay full sizeFigure 13 Diagrams of axial vorticity at different attack angle S3 sections of a highly-loaded helium compressor cascadeDisplay full sizeFigure 14 Vortex loss weights of S3 sections of helium compressor cascade with different attack anglesDisplay full sizeFigure 15 Static pressure distribution on cascade surface of highly-loaded helium compressor under different incoming Mach numbersDisplay full sizeFigure 16 Diagrams of axial vorticity at different incoming Mach numbers for the S3 sections of a highly-loaded helium compressor cascadeDisplay full sizeFigure 17 Vortex loss weights of S3 sections of helium compressor cascades under different incoming Mach numberDisplay full sizeFigure 18 Variation of total pressure loss coefficient and pressure ratio with attack angle for compressor cascade with different working fluidDisplay full sizeFigure 19 Diagrams of static pressure ratio at 50% spanwise section for different working fluids (0.3Ma, i=0°)Display full sizeFigure 20 Diagrams of cascade S3 sections axial vorticity with different working fluid (Ma=0.3, i=0°)Display full sizeFigure 21 Vortex loss weights of S3 sections of different working fluid compressor cascadesDisplay full sizeAdditional informationFundingThe work was supported by the National Natural Science Foundation of China [52206042].