Shi L.,Northern Polytechnical University |
Liu B.,Northern Polytechnical University |
Na Z.-Z.,Northern Polytechnical University |
Zhang G.-C.,Northern Polytechnical University |
Li J.,Northern Polytechnical University
Tuijin Jishu/Journal of Propulsion Technology | Year: 2015
A compressor cascade end-wall was set in middle span of the middle passage to study the end-wall flow field without horseshoe vortex effect. Structures of end-wall flow field with 4 kinds of suction rate at design point were displayed by oil flow visualization method. Eight equidistant static pressure holes along the pitchwise at the suction hole chordwise were tested. Fine/Turbo software was used in the full-passage numerical simulation in supplementary analysis. Investigations show that in original cascade end-wall, the pressure branch of horseshoe vortex passes through the passage having no effect on suction surface. So, the removal of horseshoe vortex on end-wall mainly improves the blade loading near leading edge. There is an improvement of 15.5% on blade loading in the first 40% axial position near the end-wall. As the suction flow increasing, the blade loading improves and efficiency of suction rate decreases. Minimum connection in the entropy distribution contour near the leading edge in the numerical calculation proves that the angle of θ measured in the oil visualization reflects the turbulent zone caused by the leading edge. ©, 2015, Editorial Department of Journal of Propulsion Technology. All right reserved.
Ma K.,University of Electronic Science and Technology of China |
Fan L.,Northern Polytechnical University |
Zhang S.,Xi'an Jiaotong University
Electronics Letters | Year: 2015
A new self-packaged bandpass filter by using multilayer print circuit board technology is proposed and investigated. By using a multilayer structure, a lumped step-impedance resonator as well as self-packaging, the designed filter can achieve a much more compact size, low insertion loss and a wide stopband. The implemented filter operated at a centre frequency of 800 MHz with a 3 dB bandwidth of 120 MHz demonstrates stopband rejection better than 25 dB up to 4 GHz. The measured insertion loss including the connector loss in the input and output is 1.48 dB. The size of the filter is only 12 × 8 mm, i.e. 0.059λg × 0.039λg. © The Institution of Engineering and Technology 2015.