The distributions of strata rock temperature around a driving head with auxil- iary ventilation were analyzed theoretically based on a program which was developed by the authors to predict the thermal environmental co...The distributions of strata rock temperature around a driving head with auxil- iary ventilation were analyzed theoretically based on a program which was developed by the authors to predict the thermal environmental conditions in a development heading with forcing auxiliary ventilation. The influences of wetness of the airway surface were dis- cussed on the cooled zone of the strata rock and on the temperature distribution in the surrounding rock. It is shown that the advancing speed and driving time have little influ- ence on the temperature profile in front of the working face of a driving airway, and the rock temperature 1.5 m ahead of the working face can be taken as the virgin rock tem- perature.展开更多
Gortler vortices are key issues in the design of gas turbine blades. The present study deals with flow visualization over concave surface for gas turbine applications. The aim is to comprehend qualitatively the flow t...Gortler vortices are key issues in the design of gas turbine blades. The present study deals with flow visualization over concave surface for gas turbine applications. The aim is to comprehend qualitatively the flow trends, particularly the Gortler vortices formation and development. Gortler vortices have the shape of mushroom-like vortices regularly spaced at 25 mm. These vortices grow and increase in strength more rapidly along the surface in the case of the same grid of turbulence applied to the measuring section. The curvature radius of the studied blade is 0.5 m and the stream turbulence intensity level is 2.6%. The velocity field is measured by hot wire anemometer in the streamwise direction. The velocity profile is found to be highly distorted by the momentum transfer associated with Gortler vortices. The results are compared to Blasius flow and to literature data for a blade with curvature radius equal to 2 m.展开更多
A description and results of tests of a new small-scale gage for direct measurement of skin friction force are presented in the paper.The gage design provides separated measurement of longitudinal and transversal comp...A description and results of tests of a new small-scale gage for direct measurement of skin friction force are presented in the paper.The gage design provides separated measurement of longitudinal and transversal component of friction force.Application of this scheme provides high sensitivity and necessary high-frequency response of the gage.The tests of the gage were carried out in a blow down wind tunnel at Mach numbers of 2 and 4 within the range of Reynolds numbers Rex from 0.8 to 5 million and in the hot-shot wind tunnel at Mach number 6 and Reynolds numbers Rex=2.5-10 million.The measurements of skin friction were carried out on a flat plate and on a ramp beyond the shock wave.Simultaneously with the direct measurement of friction in the blow down wind tunnel,the measurements of profiles of average velocities and mass flow rate pulsations were realised.Analysis of measurement errors has shown that the friction gage permits to measure skin friction coefficient on a flat plate with mistake not more than 10%.展开更多
基金Supported by Natural Science Foundation of Henan Province (0311051900)Supported by Fundamental Research Project of Education De-partment of Henan Province (2003440221)
文摘The distributions of strata rock temperature around a driving head with auxil- iary ventilation were analyzed theoretically based on a program which was developed by the authors to predict the thermal environmental conditions in a development heading with forcing auxiliary ventilation. The influences of wetness of the airway surface were dis- cussed on the cooled zone of the strata rock and on the temperature distribution in the surrounding rock. It is shown that the advancing speed and driving time have little influ- ence on the temperature profile in front of the working face of a driving airway, and the rock temperature 1.5 m ahead of the working face can be taken as the virgin rock tem- perature.
文摘Gortler vortices are key issues in the design of gas turbine blades. The present study deals with flow visualization over concave surface for gas turbine applications. The aim is to comprehend qualitatively the flow trends, particularly the Gortler vortices formation and development. Gortler vortices have the shape of mushroom-like vortices regularly spaced at 25 mm. These vortices grow and increase in strength more rapidly along the surface in the case of the same grid of turbulence applied to the measuring section. The curvature radius of the studied blade is 0.5 m and the stream turbulence intensity level is 2.6%. The velocity field is measured by hot wire anemometer in the streamwise direction. The velocity profile is found to be highly distorted by the momentum transfer associated with Gortler vortices. The results are compared to Blasius flow and to literature data for a blade with curvature radius equal to 2 m.
文摘A description and results of tests of a new small-scale gage for direct measurement of skin friction force are presented in the paper.The gage design provides separated measurement of longitudinal and transversal component of friction force.Application of this scheme provides high sensitivity and necessary high-frequency response of the gage.The tests of the gage were carried out in a blow down wind tunnel at Mach numbers of 2 and 4 within the range of Reynolds numbers Rex from 0.8 to 5 million and in the hot-shot wind tunnel at Mach number 6 and Reynolds numbers Rex=2.5-10 million.The measurements of skin friction were carried out on a flat plate and on a ramp beyond the shock wave.Simultaneously with the direct measurement of friction in the blow down wind tunnel,the measurements of profiles of average velocities and mass flow rate pulsations were realised.Analysis of measurement errors has shown that the friction gage permits to measure skin friction coefficient on a flat plate with mistake not more than 10%.
