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| 1 | Turbulent characteristics and rotation correction of wall function in rotating channel with high local rotation parameter显示文摘The turbulent fluctuation and the rotation correction of wall function law are investigated in the entrance section of a rotating channel. The one-dimensional hot wire probe and the X-type probe are utilized to measure the boundary layer at four streamwise stations. Through the analysis on the boundary layer near the leading side and trailing side, it is found that the turbulent fluctuation is promoted in the trailing side whereas suppressed in the leading side. This difference is attributed to the Coriolis instability near the trailing side. In addition, considering the local rotation parameter Rc, whose maximum absolute value is 0.014, is larger than that in previous research, whose maximum value is 0.007, the whole process of the relaminarization is captured. To understand this phenomenon better, the effects of the generation term and the Coriolis term in the transport equation of the Reynolds stress are discussed. In addition, the rotation correction of the viscous-Coriolis region and the Coriolis region are discussed, a new revising method for the wall function is proposed. | Zhi TAO Huijie WU Ruquan YOU Haiwang LI Kuan WEI | 2018 | Chinese Journal of Aeronautics2018，31，10： | 4 |
| 2 | Hot-wire experimental investigation on turbulent Prandtl number in a rotating non-isothermal turbulent boundary layer显示文摘This experiment used a parallel array of hot wire probes to simultaneously measure the temperature and velocity fields in the non-isothermal turbulent boundary layer of a rotating straight channel. The Reynolds numbers are 15,000 and 25,000, respectively. The rotation numbers are 0, 0.07, 0.14, 0.21 and 0.28, respectively. The purpose of this study is to calculate the turbulent Prandtl number in a rotating non-isothermal turbulent boundary layer. Due to the difficulty in measuring local turbulent Prandtl numbers, this study focuses on the average turbulent Prandtl numbers in the logarithmic region instead. Under static conditions, this value is taken as 0.9 normally. This research finds that rotation conditions can affect the turbulent Prandtl number by affecting the properties of velocity and temperature boundary layers. The change range of the turbulent Prandtl number is roughly 0.6–1.1. The influence of the leading side is greater than that of the trailing side, especially at high rotation numbers. This can provide validation and guidance for numerical simulation. Other information within the turbulent boundary layer is also discussed. It is hoped that this study would enhance our understanding of the mechanism of turbulent flow in the turbulent layer at rotating conditions. | Ran Gao Haiwang Li Ruquan You Gangfu Li Shuangzhi Xia | 2020 | Propulsion and Power Research2020，9，4： | 1 |
| 3 | Development of secondary flow field under rotating condition in a straight channel with square cross-section显示文摘The developing secondary flow fields in the entrance section of a rotating straight channel were experimentally investigated using Particle Image Velocimetry(PIV). The effects of streamwise position, Reynolds number and rotation number on the development of the secondary flow fields were revealed. The results show that the absolute values of vorticity flux of the trailing side roll cells increase with increasing radius of the measured plane and rotation number. When the absolute value of vorticity flux exceeds a critical value, the merging of the trailing side roll cells appears. Moreover, when the number of the trailing side vortex pairs is even, the absolute values of vorticity flux of the leading side vortices increase along streamwise direction. Otherwise, the absolute values decrease along the streamwise direction. By the circulation analysis, this phenomenon was found to have relationship with the merging of the trailing side roll cells, and further concluded that the secondary flow field in a rotating channel has to be treated as a whole. At last,the increase of the Reynolds number was found to be able to induce the merging position moves upstream. | Ruquan YOU Kuan WEI Zhi TAO Haiwang LI Guoqiang XU | 2018 | Chinese Journal of Aeronautics2018，31，8： | 1 |
| 4 | Experimental Investigation of the Secondary Flow in a Rotating Smooth Channel Subjected to Thermal Boundary Conditions显示文摘In the current study,thermal boundary conditions are considered in a rotating smooth channel with a square cross-section to investigate the secondary flow and compare it to that of the same channel without heating.The measurement is conducted at three streamwise planes(X=445 mm,525 mm,605 mm).The flow parameters are the Reynolds number(Re=4750,which was based on the average longitudinal or primary velocity U and the hydraulic diameter D of the channel cross-section),the rotation number(Ro=?D/U,where?is the rotational velocity,ranging from 0 to 0.26),and the aspect ratio of the channel cross-section(AR=1,which is calculated by dividing the channel height by the channel width).The leading and trailing walls are heated under a constant heat flux qw=380 W/m^2,and the top and bottom walls are isothermal at room temperature.This work is in a series with our previous work without thermal boundary conditions.Based on the experimental data,we obtained a four-vortex regime.There is a counter-rotating vortex pair near the leading side and the trailing side.Because the leading and trailing walls are heated,the buoyancy force increases the relative vertical position of the vortex pair near the trailing side from 5%to 12.5%of the hydraulic diameter.When moving upstream along the streamwise direction,the upper vortex near the trailing wall becomes weaker,whereas the lower vortex becomes stronger.As the rotational speed increases,the vortex pair near the trailing side is inhibited by the Coriolis force.Under heated thermal boundary conditions,the vortex pair near the trailing side reappears due to the effect of buoyancy force.These results indicate that the buoyancy force has a substantial effect on the secondary flow regime under thermal boundary conditions. | LI Haiwang YOU Haoliang YOU Ruquan TAO Zhi | 2020 | Journal of Thermal Science2020，29，6： | 1 |
| 5 | Experimental Study on the Film Cooling Characteristics of Three Complex Tip Structures显示文摘The turbine blades of aircrafts must be properly cooled to prevent engine failure.Thus,to investigate the influence of the tip structure on the film cooling effect,pressure-sensitive paint test technology was used to determine the adiabatic film cooling effectiveness in this study.The experiment was completed in a cascade comprising three straight blades.The effects of the blowing ratio,density ratio,tip clearance,and tip structure on film cooling efficiency were analyzed.The experimental results demonstrated that,as the blowing ratio increased,the film coverage area and film cooling efficiency increased under most experimental conditions.However,the film cooling efficiency was found to initially increase,and subsequently decrease,as the blowing ratio increased.The respective influences of the density ratio and tip clearance on the film cooling efficiency were found to be significant.The density ratio experiments revealed that a high-density ratio can result in better film coverage than the low-density-ratio air.The tip clearance experimental results indicated that a small tip clearance promotes an increase in film cooling efficiency;this is because the small tip clearance negatively affects the main stream leakage flow,which can reduce the film coverage area.Under the conditions of the Base case 2 configuration,a blowing ratio of 2.1,and a tip clearance of 0.6%h,the average film cooling efficiency of the blade tip was 0.22.Among the three blade tip structures applied in this study,Base case 2 demonstrated higher film cooling efficiency than the other two blade tip structures under the conditions of the same blowing ratio,tip clearance,and density ratio. | LIN Juqiang LI Haiwang YOU Ruquan LIU Runzhou TAO Zhi LIU Song | 2023 | Journal of Thermal Science2023，32，4： | 0 |
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