This paper presents a method based on riblet surfaces. Its advantage lies in that it is more with testing methods using instruments such as a the Spalding formula for testing drag-reduction on convenient and yields mo...This paper presents a method based on riblet surfaces. Its advantage lies in that it is more with testing methods using instruments such as a the Spalding formula for testing drag-reduction on convenient and yields more precise data compared scale. With this method, data is obtained from the velocity distribution within the inner layer, nearest the riblet surface. Precision of measurement of the velocity distribution is the key factor affecting the precision of the testing.展开更多
It is a very difficult task to develop a method of reducing turbulent boundary layer drag.However,in recent years,plasma flow control technology has demonstrated huge potential in friction drag reduction.To further in...It is a very difficult task to develop a method of reducing turbulent boundary layer drag.However,in recent years,plasma flow control technology has demonstrated huge potential in friction drag reduction.To further investigate this issue,a smooth plate model was designed as a testing object arranged with a bidirectional dielectric-barrier-discharge(DBD)plasma actuator.In addition,measurement of skin friction drag was achieved by applying hot wire anemometry to obtain the velocity distribution of the turbulent boundary layer.A method of quantifying the friction drag effect was adopted based on the Spalding formula fitted with the experiment data.When plasma actuation was conducted,a velocity defect occurred at the two measuring positions,compared with the no plasma control condition;this means that the DBD plasma actuation could reduce the drag successfully in the downstream of the actuator.Moreover,drag reduction caused by backward actuation was slightly more efficient than that caused by forward actuation.With an increasing distance from plasma actuation,the drag-reduction effect could become weaker.Experimental results also show that the improvement of drag-reduction efficiency using a DBD plasma actuator can achieve about 8.78%in the local region of the experimental flat model.展开更多
基金Supported by National Natural Science Foundation (50835009 and 10672136)Science and Technology Innovation Foundation of NWPU(2008KJ02012)
文摘This paper presents a method based on riblet surfaces. Its advantage lies in that it is more with testing methods using instruments such as a the Spalding formula for testing drag-reduction on convenient and yields more precise data compared scale. With this method, data is obtained from the velocity distribution within the inner layer, nearest the riblet surface. Precision of measurement of the velocity distribution is the key factor affecting the precision of the testing.
文摘It is a very difficult task to develop a method of reducing turbulent boundary layer drag.However,in recent years,plasma flow control technology has demonstrated huge potential in friction drag reduction.To further investigate this issue,a smooth plate model was designed as a testing object arranged with a bidirectional dielectric-barrier-discharge(DBD)plasma actuator.In addition,measurement of skin friction drag was achieved by applying hot wire anemometry to obtain the velocity distribution of the turbulent boundary layer.A method of quantifying the friction drag effect was adopted based on the Spalding formula fitted with the experiment data.When plasma actuation was conducted,a velocity defect occurred at the two measuring positions,compared with the no plasma control condition;this means that the DBD plasma actuation could reduce the drag successfully in the downstream of the actuator.Moreover,drag reduction caused by backward actuation was slightly more efficient than that caused by forward actuation.With an increasing distance from plasma actuation,the drag-reduction effect could become weaker.Experimental results also show that the improvement of drag-reduction efficiency using a DBD plasma actuator can achieve about 8.78%in the local region of the experimental flat model.
