In order to study component matching which exists in off-design situation at the initial design stage of turbine engine,by establishing performance analysis model of low bypass ratio mixed flow turbofan engine and com...In order to study component matching which exists in off-design situation at the initial design stage of turbine engine,by establishing performance analysis model of low bypass ratio mixed flow turbofan engine and components characteristic data,and by applying Newton-Raphson method to solve the nonlinear equations of offdesign points in flying envelop,the factors which affect matching between engine components are studied.The results show that low pressure turbine(LPT)must not operate in a critical condition,and the partial derivative(slope)of pressure ratio to similitude mass flow ratio of working point in LPT characteristic map affects the stability of engine.The smaller the slope is,the more stable the engine is.In addition,the engine is more stable when the fan characteristic map is steep.展开更多
Aerodynamic noise control is one of the key technologies in the development of stealth technology of torpedo. The noise producing mechanism in an ultra-high expansion ratio turbine with partial admission were discusse...Aerodynamic noise control is one of the key technologies in the development of stealth technology of torpedo. The noise producing mechanism in an ultra-high expansion ratio turbine with partial admission were discussed. Wide wakes originating from non-outlet region between elliptical nozzles,circumferential non-uniformity owing to partial admission design and complex shock system formed in narrow space between nozzles and rotors are three main sources of aerodynamic noise in this turbine. Thus,two kinds of aerodynamic noise control methods were put forward,namely adding axial gap between the nozzle and rotor,nozzle-down,bilateral repair and trailing edge blowing. Steady annulus simulation results showed that the aerodynamic noise was significantly reduced by more than 10 dB after optimization,which had little impact on the aerodynamic performance of the turbine.展开更多
The Front Variable Area Bypass Injector(FVABI)is a key to bypass ratio adjustment for a Variable Cycle Engine(VCE).In order to study the role of the FVABI with the Core Driven Fan Stage(CDFS)duct,firstly,the engine by...The Front Variable Area Bypass Injector(FVABI)is a key to bypass ratio adjustment for a Variable Cycle Engine(VCE).In order to study the role of the FVABI with the Core Driven Fan Stage(CDFS)duct,firstly,the engine bypass with the CDFS duct model and the equivalent engine bypass without the CDFS duct model are designed using the concept of a jet boundary line.By comparing the difference between airflow driving forces in the two engine bypass models,the quantitative effects of the injection from the CDFS duct on the mass flow rate of the engine bypass airflow are obtained under different combinations of pressure difference and area ratios.Then,the CDFS duct injection characteristic map is obtained through the typical experiment of the FVABI.Based on this map,the performance model of the FVABI is developed.Finally,the turbofan engine model with the Variable Inlet Guide Vane(VIGV),the First Variable Cycle Engine model(VCE1)with the CDFS duct and without the VIGV,and the Second Variable Cycle Engine model(VCE2)with the CDFS duct and VIGV are built.The gain on the engine bypass ratio adjustment range caused by the injection from the CDFS duct is clarified by comparing the three engine models.It is concluded that the bypass ratio adjustment range of the variable cycle engine with the FVABI is about twice that of the traditional turbofan engine.展开更多
目的探讨患者术前中性粒细胞/淋巴细胞比值(NLR)对非体外循环下冠状动脉旁路移植术(OPCABG)后心肌损伤以及临床预后的影响。方法选取2014年1月—2019年12月我院收治的314名行OPCABG的患者,依据患者术前NLR的三分位数分为高比值组(NLR>...目的探讨患者术前中性粒细胞/淋巴细胞比值(NLR)对非体外循环下冠状动脉旁路移植术(OPCABG)后心肌损伤以及临床预后的影响。方法选取2014年1月—2019年12月我院收治的314名行OPCABG的患者,依据患者术前NLR的三分位数分为高比值组(NLR>2.8,n=102)、中比值组(2.8≥NLR≥1.6,n=106)以及低比值组(NLR<1.6,n=106)。分别检测患者术前基线、术后8 h及术后24 h肌酸激酶同工酶(CKMB)及肌钙蛋白(CTnI)水平。结果高比值组患者术后心肌损伤发生率显著高于中比值组及低比值组(P<0.05)。高比值组术后CKMB峰值显著高于中比值组[2.1(1.2~13.0)ng/mL vs 2.0(1.0~7.3)ng/mL,P=0.047]及低比值组[2.1(1.2~13.0)ng/mL vs 1.1(0.9~1.6)ng/mL,P<0.001]。且高比值组患者术后CTnI峰值同样显著高于中比值组[0.075(0.010~0.185)ng/mL vs 0.020(0.000~0.103)ng/mL,P=0.011],以及低比值组[0.075(0.010~0.185)ng/mL vs 0.010(0.000~0.030)ng/mL,P<0.001]。术前NLR较高是术后患者CTnI升高的独立危险因素(OR:2.809;95%CI:1.326~5.954;P=0.007)。高比值组患者1年不良心血管事件发生率显著高于中比值组及低比值组(HR:1.80;95%CI:1.16~2.79;Log Rank P=0.021)。结论患者术前中性粒细胞/淋巴细胞比值升高是非体外循环冠状动脉旁路移植术后心肌损伤的独立危险因素,而且会增加患者不良心血管事件。展开更多
基金supported in part by the Fundamental Research Funds for the Central Universities(No.NZ2016103)
文摘In order to study component matching which exists in off-design situation at the initial design stage of turbine engine,by establishing performance analysis model of low bypass ratio mixed flow turbofan engine and components characteristic data,and by applying Newton-Raphson method to solve the nonlinear equations of offdesign points in flying envelop,the factors which affect matching between engine components are studied.The results show that low pressure turbine(LPT)must not operate in a critical condition,and the partial derivative(slope)of pressure ratio to similitude mass flow ratio of working point in LPT characteristic map affects the stability of engine.The smaller the slope is,the more stable the engine is.In addition,the engine is more stable when the fan characteristic map is steep.
基金Sponsored by the National Key Basic Research Special Foundation of China(Grant No.613188020201)
文摘Aerodynamic noise control is one of the key technologies in the development of stealth technology of torpedo. The noise producing mechanism in an ultra-high expansion ratio turbine with partial admission were discussed. Wide wakes originating from non-outlet region between elliptical nozzles,circumferential non-uniformity owing to partial admission design and complex shock system formed in narrow space between nozzles and rotors are three main sources of aerodynamic noise in this turbine. Thus,two kinds of aerodynamic noise control methods were put forward,namely adding axial gap between the nozzle and rotor,nozzle-down,bilateral repair and trailing edge blowing. Steady annulus simulation results showed that the aerodynamic noise was significantly reduced by more than 10 dB after optimization,which had little impact on the aerodynamic performance of the turbine.
基金Supported by the National Science and Technology Major Project of China(No.J2019-II-0007-0027)the China Academy of Launch Vehicle Technology Funding(No.CALT2023-07).
文摘The Front Variable Area Bypass Injector(FVABI)is a key to bypass ratio adjustment for a Variable Cycle Engine(VCE).In order to study the role of the FVABI with the Core Driven Fan Stage(CDFS)duct,firstly,the engine bypass with the CDFS duct model and the equivalent engine bypass without the CDFS duct model are designed using the concept of a jet boundary line.By comparing the difference between airflow driving forces in the two engine bypass models,the quantitative effects of the injection from the CDFS duct on the mass flow rate of the engine bypass airflow are obtained under different combinations of pressure difference and area ratios.Then,the CDFS duct injection characteristic map is obtained through the typical experiment of the FVABI.Based on this map,the performance model of the FVABI is developed.Finally,the turbofan engine model with the Variable Inlet Guide Vane(VIGV),the First Variable Cycle Engine model(VCE1)with the CDFS duct and without the VIGV,and the Second Variable Cycle Engine model(VCE2)with the CDFS duct and VIGV are built.The gain on the engine bypass ratio adjustment range caused by the injection from the CDFS duct is clarified by comparing the three engine models.It is concluded that the bypass ratio adjustment range of the variable cycle engine with the FVABI is about twice that of the traditional turbofan engine.
文摘目的探讨患者术前中性粒细胞/淋巴细胞比值(NLR)对非体外循环下冠状动脉旁路移植术(OPCABG)后心肌损伤以及临床预后的影响。方法选取2014年1月—2019年12月我院收治的314名行OPCABG的患者,依据患者术前NLR的三分位数分为高比值组(NLR>2.8,n=102)、中比值组(2.8≥NLR≥1.6,n=106)以及低比值组(NLR<1.6,n=106)。分别检测患者术前基线、术后8 h及术后24 h肌酸激酶同工酶(CKMB)及肌钙蛋白(CTnI)水平。结果高比值组患者术后心肌损伤发生率显著高于中比值组及低比值组(P<0.05)。高比值组术后CKMB峰值显著高于中比值组[2.1(1.2~13.0)ng/mL vs 2.0(1.0~7.3)ng/mL,P=0.047]及低比值组[2.1(1.2~13.0)ng/mL vs 1.1(0.9~1.6)ng/mL,P<0.001]。且高比值组患者术后CTnI峰值同样显著高于中比值组[0.075(0.010~0.185)ng/mL vs 0.020(0.000~0.103)ng/mL,P=0.011],以及低比值组[0.075(0.010~0.185)ng/mL vs 0.010(0.000~0.030)ng/mL,P<0.001]。术前NLR较高是术后患者CTnI升高的独立危险因素(OR:2.809;95%CI:1.326~5.954;P=0.007)。高比值组患者1年不良心血管事件发生率显著高于中比值组及低比值组(HR:1.80;95%CI:1.16~2.79;Log Rank P=0.021)。结论患者术前中性粒细胞/淋巴细胞比值升高是非体外循环冠状动脉旁路移植术后心肌损伤的独立危险因素,而且会增加患者不良心血管事件。
文摘描述中国航发商用航空发动机有限公司(商发公司)新研制的大涵道比风扇声学试验器(Fan Aeroacoustic Test Facility,FATF)的初步设计方案和声学调试结果。FATF配备尺寸36 m×33 m×15 m、截止频率100 Hz的全消声室,是目前国内最大的风扇声学试验全消声室。FATF还配备进气整流罩(Turbulence Control Screen,TCS)、远场声阵列等试验设备,满足风扇远场噪声试验需求。对FATF全消声室自由声场、频率范围和背景噪声进行调试和校准,结果显示,全消声室的自由声场频率范围、背景噪声等技术指标均完全满足设计要求,证明FATF的全消声室技术指标均已达到国际先进水平,可满足后续风扇气动声学试验需求,支撑航空发动机风扇的降噪设计与改进优化。
