Peformance enhancing drugs are widely used today in different sport fields, and therefore the successful anti-doping activity should be based not only on regular doping controls, but also it should show the real alter...Peformance enhancing drugs are widely used today in different sport fields, and therefore the successful anti-doping activity should be based not only on regular doping controls, but also it should show the real alternative： how to replace the forbidden doping substances with legal and effective supplements. The paper deals with application proposition of protein concentrates, free AA （amino acids）, HMB （hydroxy-methyle-butyrate）, creatine and camitine. If the athlete is involved in strength and power sport （e.g. throwing events in track and field, olympic weightlifting etc.）, the explosive and maximum strength is of primary importance. For strength athletes, these mentioned substances are those legal preparates, supplements, which can help effectively in performance improvement of sport results. The main reason is that using protein concentrates, AAs, HMB, creatine and camitine, the anabolic （and anticatabolic） effect will enhance the protein biosynthesis of the organism, improve the aerob and anaerob capacity of the athletes, activate and stimulate the own hormonal system. And the final result is creating higher loadability because of the faster recovery, and higher performance level on the competition. Of course, the athletes--as a minimum requirement--need an adequate nutrition （good balanced nourishment）, as well, with appropriate application and supplementation of all vitamins and essential minerals.展开更多
Flow measurement is important in the fluid process and transmission system. For the need of accuracy measure- ment of fluid, stable flow is acquired. However, the elbows and devices as valves and rotary machines may p...Flow measurement is important in the fluid process and transmission system. For the need of accuracy measure- ment of fluid, stable flow is acquired. However, the elbows and devices as valves and rotary machines may pro- duce swirling flow in the natural gas pipeline networks system and many other industry fields. In order to reveal the influence of upstream swirling flow on internal flow fields and the metrological characteristics, numerical si- mulations are carried out on the swirl meter. Using RNG k-e turbulent model and SIMPLE algorithm, the flow field is numerically simulated under swirling flows generated from co-swirl and counter-swirl flow. Simulation results show fluctuation is enhanced or weakened depending on the rotating direction of swirling flow. A coun- ter-swift flow increases the entropy production rate at the inlet and outlet of the swirler, the junction region between throat and divergent section, and then the pressure loss is increased. The vortex precession dominates the static pressure distributions on the solid walls and in the channel, especially at the end region of the throat.展开更多
Since the automobile turbochargers are installed in an engine compartment with limited space, the ducts upstream of the turbocharger compressor may be curved in a complex manner. In the present paper, the effect of a ...Since the automobile turbochargers are installed in an engine compartment with limited space, the ducts upstream of the turbocharger compressor may be curved in a complex manner. In the present paper, the effect of a curved duct upstream on performance of small centrifugal compressors for automobile turbochargers is discussed. The computational fluid dynamics (CFD) analysis of a turbocharger compressor validated for the compressor model with the straight pipe applied to the compressor with the curved pipe are executed, and the deterioration of the performance for the curved pipe is confirmed. It is also found that the deterioration of compressor performance is caused by the interaction of the secondary flow and the impeller.展开更多
A new approach,mass injection near the slat cusp,is proposed for the suppression of slat noise.The mechanism and efciency of the slat noise suppression using upstream mass injection are numerically studied with hybrid...A new approach,mass injection near the slat cusp,is proposed for the suppression of slat noise.The mechanism and efciency of the slat noise suppression using upstream mass injection are numerically studied with hybrid Reynolds-averaged Navier-Stokes simulation/Large eddy simulation(RANS/LES)of a three-component high-lift model.Ffowcs-Williams and Hawking(FW-H)integration is employed to obtain far-field acoustic characteristics.Results show that with injection,aerodynamic capability of the high-lift devices is sustained.In addition,a considerable noise reduction is observed in the downward direction.With detailed analysis of the time-averaged and instantaneous flow fields,two mechanisms are identified as the reason accounting for the noise suppression:upstream mass injection significantly reduces the scale and strength of the vortices stemming from the cusp;the shear layer is lifted up,which relieves the shear layer impingement on the slat lower surface.展开更多
文摘Peformance enhancing drugs are widely used today in different sport fields, and therefore the successful anti-doping activity should be based not only on regular doping controls, but also it should show the real alternative： how to replace the forbidden doping substances with legal and effective supplements. The paper deals with application proposition of protein concentrates, free AA （amino acids）, HMB （hydroxy-methyle-butyrate）, creatine and camitine. If the athlete is involved in strength and power sport （e.g. throwing events in track and field, olympic weightlifting etc.）, the explosive and maximum strength is of primary importance. For strength athletes, these mentioned substances are those legal preparates, supplements, which can help effectively in performance improvement of sport results. The main reason is that using protein concentrates, AAs, HMB, creatine and camitine, the anabolic （and anticatabolic） effect will enhance the protein biosynthesis of the organism, improve the aerob and anaerob capacity of the athletes, activate and stimulate the own hormonal system. And the final result is creating higher loadability because of the faster recovery, and higher performance level on the competition. Of course, the athletes--as a minimum requirement--need an adequate nutrition （good balanced nourishment）, as well, with appropriate application and supplementation of all vitamins and essential minerals.
基金supported by the National Natural Science Foundation of China(51579225)
文摘Flow measurement is important in the fluid process and transmission system. For the need of accuracy measure- ment of fluid, stable flow is acquired. However, the elbows and devices as valves and rotary machines may pro- duce swirling flow in the natural gas pipeline networks system and many other industry fields. In order to reveal the influence of upstream swirling flow on internal flow fields and the metrological characteristics, numerical si- mulations are carried out on the swirl meter. Using RNG k-e turbulent model and SIMPLE algorithm, the flow field is numerically simulated under swirling flows generated from co-swirl and counter-swirl flow. Simulation results show fluctuation is enhanced or weakened depending on the rotating direction of swirling flow. A coun- ter-swift flow increases the entropy production rate at the inlet and outlet of the swirler, the junction region between throat and divergent section, and then the pressure loss is increased. The vortex precession dominates the static pressure distributions on the solid walls and in the channel, especially at the end region of the throat.
文摘Since the automobile turbochargers are installed in an engine compartment with limited space, the ducts upstream of the turbocharger compressor may be curved in a complex manner. In the present paper, the effect of a curved duct upstream on performance of small centrifugal compressors for automobile turbochargers is discussed. The computational fluid dynamics (CFD) analysis of a turbocharger compressor validated for the compressor model with the straight pipe applied to the compressor with the curved pipe are executed, and the deterioration of the performance for the curved pipe is confirmed. It is also found that the deterioration of compressor performance is caused by the interaction of the secondary flow and the impeller.
文摘A new approach,mass injection near the slat cusp,is proposed for the suppression of slat noise.The mechanism and efciency of the slat noise suppression using upstream mass injection are numerically studied with hybrid Reynolds-averaged Navier-Stokes simulation/Large eddy simulation(RANS/LES)of a three-component high-lift model.Ffowcs-Williams and Hawking(FW-H)integration is employed to obtain far-field acoustic characteristics.Results show that with injection,aerodynamic capability of the high-lift devices is sustained.In addition,a considerable noise reduction is observed in the downward direction.With detailed analysis of the time-averaged and instantaneous flow fields,two mechanisms are identified as the reason accounting for the noise suppression:upstream mass injection significantly reduces the scale and strength of the vortices stemming from the cusp;the shear layer is lifted up,which relieves the shear layer impingement on the slat lower surface.
