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1. chinaXiv:201706.00772 [pdf]

Hydrodynamics in a circulating fluidized bed with annular furnace and six parallel cyclones

Shuai Daping; Wang Xiaofang; Lyu Qinggang
Subjects: Dynamic and Electric Engineering >> Engineering Thermophysics

Systematic measurements were conducted on a cold CFB with annular furnace and six parallel cyclones to study gas-solids flow in the annular furnace and flow non-uniformity among six cyclones. The results show that axial solids holdup in the annular furnace decreases exponentially with height, similar to the conventional rectangular furnace. The uniform transverse distribution of solids holdup suggests a good gas-solids mixing in the annular furnace. The annular furnace presents the core/double-annulus flow structure, and it results in enhanced gas-solids back-mixing than the conventional core/annulus flow structure. The gas-solids flow of the inner wall-layer and the outer wall-layer is very close at most part of the furnace height, and the wall-layer thickness decreases with height. Flow non-uniformity exists among six parallel cyclones in the annular furnace CFB. But non-uniform distribution of solids circulating rates and cyclone pressure drops show no regularity, and the flow non-uniformity is no larger than the CFBs with conventional furnace. Under typical operating conditions, the relative deviation of six solids circulating rates is 8.0%.

submitted time 2017-06-26 From cooperative journals:《暖科学学报》 Hits1048, Downloads209, Comment 0

2. chinaXiv:201706.00763 [pdf]

Numerical Investigation of the Effects of ITD Length on Low Pressure Nozzle

Liu, Guang; Liu, Jun; Liu, Hongrui; Wang, Pei; Du, Qiang
Subjects: Dynamic and Electric Engineering >> Engineering Thermophysics

The advantage of high efficiency, low SFC (Specific Fuel Consumption), ultra-high bypass ratio turbofan engine attracts more and more attention in modern commercial engine. The intermediate turbine duct (ITD), which connects high pressure turbine (HPT) with low pressure turbine (LPT), has a critical impact on the overall performance of turbine by guiding flow coming from HPT to LPT without too much loss. Therefore, it becomes more and more urgent to master the technique of designing aggressive, even super-aggressive ITD. Much more concerns have been concentrated on the duct. However, in order to further improve turbine, LPT nozzle is arranged into ITD to shorten low pressure axle. With such design concept, it is obvious that LPT nozzle flow field is easily influenced by upstream duct structure, but receives much less interests on the contrary. In this paper, numerical method is used to investigate the effects of length of ITD with upstream swirl blades on LPT nozzle. Nine models with the same swirl and nozzle blades, while the length of ITD is the only parameter to be changed, will be discussed. Finally, several conclusions and advices for designers are summarized. After changing axial length of ducts, inlet and outlet flow field of nozzle differs, correspondingly. On the other hand, the shearing stress on nozzle blade (suction and pressure) surface presents individual feature under various inlet flow. In addition to that, "Clocking-like effect" is described in this paper, which will contribute much to the pressure loss and should be paid enough attention.

submitted time 2017-06-26 From cooperative journals:《暖科学学报》 Hits534, Downloads260, Comment 0

3. chinaXiv:201703.00252 [pdf]

AN UNFOCUSED SAR APPROACH TO IMPROVE AZIMUTH RESOLUTION OF DUAL-FREQUENCY POLARIZED SCATTEROMETER(DFPSCAT)

Gang Wang; Xiaolong Dong; Qingliu Bao; Di Zhu; Xingou Xu
Subjects: Geosciences >> Space Physics

For the spaceborne scanning pencil-beam scatterometer, the azimuth resolution is low that could not meet the demands. Based on the motion of platform and the scanning rules of the spaceborne scatterometer, this paper takes an unfocused SAR approach to improve the Azimuth Resolution.

submitted time 2017-03-10 Hits416, Downloads221, Comment 0

4. chinaXiv:201701.00026 [pdf]

A rigorous SAR epipolar geometry modeling and application to 3D target reconstruction

Li, Dong; Zhang, Yunhua
Subjects: Geosciences >> Space Physics

A rigorous epipolar geometry modeling for synthetic aperture radar (SAR) is developed from a concise imaging model proposed in the paper. The imaging model and epipolar model not only geometrically unify the SAR imaging and the optical camera imaging, but also motivate a 3D target reconstruction which is theoretically validated to be consistent with the radargrammetry and experimentally demonstrated to be accurate. �2008-2012 IEEE.

submitted time 2017-01-04 Hits797, Downloads418, Comment 0

5. chinaXiv:201608.00216 [pdf]

Performance of new 8-inch photomultiplier tube used for the Tibet muon-detector array

Ying Zhang; Jing Huang; Ding Chen; Liu-Ming Zhai; Xu Chen; Xiao-Bin Hu; Yu-Hui Lin; Hong-Bo Jin; Xue-Yao Zhang; Cun-Feng Feng: Huan-Yu Jia; Xun-Xiu Zhou; DANZENGLUOBU; Tian-Lu Chen; LABACIREN; Mao-Yuan Liu; Qi Gao; ZHAXICIREN
Subjects: Physics >> Nuclear Physics

A new hybrid experiment has been constructed to measure the chemical composition of cosmic rays around the "knee" in the wide energy range by the Tibet ASγ collaboration at Tibet, China, since 2014. They consist of a high-energy air-shower-core array (YAC-II), a high-density air-shower array (Tibet-III) and a large underground water-Cherenkov muon-detector array (MD). In order to obtain the primary proton, helium and iron spectra and their "knee" positions in the energy range lower than 1016 eV, each of PMTs equipped to the MD cell is required to measure the number of photons capable of covering a wide dynamic range of 100 - 106 photoelectrons (PEs) according to Monte Carlo simulations. In this paper, we firstly compare the characteristic features between R5912-PMT made by Japan Hamamatsu and CR365-PMT made by Beijing Hamamatsu. This is the first comparison between R5912-PMT and CR365-PMT. If there exists no serious difference, we will then add two 8-inch-in-diameter PMTs to meet our requirements in each MD cell, which are responsible for the range of 100 - 10000 PEs and 2000 - 1000000 PEs, respectively. That is, MD cell is expected to be able to measure the number of muons over 6 orders of magnitude.

submitted time 2016-08-31 Hits527, Downloads327, Comment 0

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