Multiscale mixing of the turbine blade tip leakage and mainstream flows causes considerable aerodynamic loss.Understanding it is crucial to correctly estimating the mixing loss and thus improving the turbine's per...Multiscale mixing of the turbine blade tip leakage and mainstream flows causes considerable aerodynamic loss.Understanding it is crucial to correctly estimating the mixing loss and thus improving the turbine's performance.The multiscale mixing phenomenon in a typical high-pressure turbine rotor flow was studied in this work.The contributions of various scale flows to entropy production and mixing properties were identified.The corresponding physical mechanisms at different scales were explored.It is shown that the large-scale and time-averaged flow contributions to mixing are significant,accounting for approximately 37.1% and 25% of the total.Time-averaged and large-scale flows cause the majority of the fluid deformation of the material surface,while mesoand small-scale flows just generate finer deformations.It raises the area stretch coefficient and the virtual concentration gradient.Thus,mixing is enhanced.Furthermore,time-averaged and large-scale flows account for the majority of the losses in the upstream and downstream regions of the blade tip respectively,accounting for approximately 53.8%and 33.5%of the total.The sheet-like structures—rather than the tip leaking vortex—are the primary source of the loss.High-dissipation regions are produced by the sheet-like structures via the pressure Hessian term and the self-amplification terms.展开更多
Diplodia tip blight,caused by Diplodia sapinea,is a global pine necrotic disease causing heavy economic losses to the pine industry.Chemical control,its main current management,easily induces pathogen resistance and e...Diplodia tip blight,caused by Diplodia sapinea,is a global pine necrotic disease causing heavy economic losses to the pine industry.Chemical control,its main current management,easily induces pathogen resistance and environmental pollution,which biological control avoids.This study investigated juniper essential oil’s efficacy against the disease on Mongolian Scots pine(Pinus sylvestris var.mongolica)and its induced resistance mechanisms via pot experiments,physiological assays(defense enzyme activities,resistant substances)and metabolomic sequencing(secondary metabolites).Results showed varied efficacy:three foliar sprays of 10μL mL^(-1) oil achieved the best control phenylalanine ammonia-lyase(PAL),polyphenol oxidase(82.9%).The 20μL mL^(-1) treatment significantly increased(PPO)activities,and contents of lignin,flavonoids and total phenolics.Metabolomic analysis showed 326 upregulated and 527 downregulated different metabolites in essential oilinduced and pathogen-inoculated pines,compared to 483 upregulated and 277 downregulated metabolites in noninduced but inoculated pines.The differentially expressed metabolites in treated pines were primarily enriched in pathways related to amino acid metabolism and plant secondary metabolite biosynthesis,with notably increased expression levels of ferulic acid,scopoletin,pipecolic acid,D-proline,and DL-arginine.Therefore,juniper essential oil protects against D.sapinea by inducing systemic acquired resistance in Mongolian Scots pine.In conclusion,juniper essential oil controls D.sapinea by inducing systemic acquired resistance(SAR)in Mongolian Scots pine,clarifying the molecular mechanism and supporting biological control of the disease.展开更多
基金supported by the National Science and Technology Major Project,China(No.J2019-Ⅱ-0012-0032)。
文摘Multiscale mixing of the turbine blade tip leakage and mainstream flows causes considerable aerodynamic loss.Understanding it is crucial to correctly estimating the mixing loss and thus improving the turbine's performance.The multiscale mixing phenomenon in a typical high-pressure turbine rotor flow was studied in this work.The contributions of various scale flows to entropy production and mixing properties were identified.The corresponding physical mechanisms at different scales were explored.It is shown that the large-scale and time-averaged flow contributions to mixing are significant,accounting for approximately 37.1% and 25% of the total.Time-averaged and large-scale flows cause the majority of the fluid deformation of the material surface,while mesoand small-scale flows just generate finer deformations.It raises the area stretch coefficient and the virtual concentration gradient.Thus,mixing is enhanced.Furthermore,time-averaged and large-scale flows account for the majority of the losses in the upstream and downstream regions of the blade tip respectively,accounting for approximately 53.8%and 33.5%of the total.The sheet-like structures—rather than the tip leaking vortex—are the primary source of the loss.High-dissipation regions are produced by the sheet-like structures via the pressure Hessian term and the self-amplification terms.
基金supported by the National Key R&D Program of China(2022YFD1401005).
文摘Diplodia tip blight,caused by Diplodia sapinea,is a global pine necrotic disease causing heavy economic losses to the pine industry.Chemical control,its main current management,easily induces pathogen resistance and environmental pollution,which biological control avoids.This study investigated juniper essential oil’s efficacy against the disease on Mongolian Scots pine(Pinus sylvestris var.mongolica)and its induced resistance mechanisms via pot experiments,physiological assays(defense enzyme activities,resistant substances)and metabolomic sequencing(secondary metabolites).Results showed varied efficacy:three foliar sprays of 10μL mL^(-1) oil achieved the best control phenylalanine ammonia-lyase(PAL),polyphenol oxidase(82.9%).The 20μL mL^(-1) treatment significantly increased(PPO)activities,and contents of lignin,flavonoids and total phenolics.Metabolomic analysis showed 326 upregulated and 527 downregulated different metabolites in essential oilinduced and pathogen-inoculated pines,compared to 483 upregulated and 277 downregulated metabolites in noninduced but inoculated pines.The differentially expressed metabolites in treated pines were primarily enriched in pathways related to amino acid metabolism and plant secondary metabolite biosynthesis,with notably increased expression levels of ferulic acid,scopoletin,pipecolic acid,D-proline,and DL-arginine.Therefore,juniper essential oil protects against D.sapinea by inducing systemic acquired resistance in Mongolian Scots pine.In conclusion,juniper essential oil controls D.sapinea by inducing systemic acquired resistance(SAR)in Mongolian Scots pine,clarifying the molecular mechanism and supporting biological control of the disease.
