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  • Author: Zhongqi Wang x
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Abstract

Situs inversus with dextrocardia is a rare condition, with complete transposition of all the body organs, including the heart. Percutaneous coronary intervention (PCI) in these patients is technically difficult because of the mirror image of organs. Here, we describe a 56-year-old man with coronary heart disease with known situs inversus with dextrocardia and coronary percutaneous intervention was performed for stenosis in the right coronary artery. A drug eluting stent was implanted at this site successfully. This case suggested that the interventional management of such patients follows the same general rules as for non-dextrocardia patients, but the manipulation of the catheter and projection position choices need to be taken into consideration to obtain optimal benefits for the patient.

Abstract

C16H13CoN4O4Br, orthorhombic, Pnna (no. 52), a = 16.921(2) Å, b = 19.211(2) Å, c = 10.2928(12) Å, V = 3345.9(7) Å3, Z = 8, R gt(F) = 0.0335, wR ref(F 2) = 0.0713, T = 296 K.

Abstract

The effects of fouling on the performance of an axial compressor rotor were investigated numerically. The NASA Rotor 37 was considered to perform a numerical investigation by means of a commercial computational fluid dynamic code. The numerical model was validated by comparing with the experimental data available from literatures. The computed performance maps and exit parameter distributions showed a good agreement with experimental data. The model was then used to simulate the effect of fouling on compressor rotor by various fouling configurations including added thickness and surface roughness levels. The mechanism of the compressor deterioration due to fouling was discussed in detail. As a result, fouling causes a significant reduction in rotor total pressure ratio and isentropic efficiency. Increased roughness was found to have a greater influence on the rotor characteristic parameters than increased blade thickness. Increased wall roughness has a weaker influence on the operation range at stable conditions than that of increased blade thickness. Increasing the blade thickness significantly reduces the operation range of the rotor at stable conditions and has a stronger influence on the stable operation of the compressor. The interaction of shock wave/boundary layer was one of the main factors that influenced the rotor characteristics.

Abstract

Unsteady pulsed suction (UPS) was applied as an unsteady flow control (UFC) technique in a certain highly loaded compressor cascade to control the flow separations. Only two bleed holes symmetrically mounted on the endwalls (one on the upper endwall and another on the lower endwall) were set up to achieve steady constant suction (SCS) and UPS. The improvements in aerodynamic performance by SCS and UPS under different time-averaged suction flow rates are firstly investigated and compared. The related unsteady aerodynamic parameters of UPS such as excitation frequency, excitation location, pitch angle, and skew angle are discussed and analyzed in detail. The results show that UPS can provide a better flow control effect than SCS with the same time-averaged dimensionless suction flow rate in the control of flow separation. The aerodynamic performance of compressor cascades can be significantly enhanced by UPS when unsteady aerodynamic parameters are in their optimum ranges. Based on the optimum parameters for UPS, the total pressure loss coefficient is reduced by 19 % only with the time-averaged dimensionless suction flow rate ms=0.4 %.

Abstract

For an explosive source used in seismic exploration, evaluating its seismic wave energy caused by explosives exploding in the soil is an important issue. The direct method, calculating RMS (root mean square) amplitude of the seismic wave propagation in different time fields, is usually used to appraise this seismic wave energy. However, the result of calculating is not only comparatively imprecise, but also the analysis on the records of seismic wave is very complex and much labor-consuming. Even so an easier and more economical way for evaluating the energy of blast-induced seismic wave is needed. In this paper, a potential pressure measuring method in the elastic zone was proposed. The experimental results showed that under the same geological condition and the same experiment condition, the characteristic of pressure wave in the elastic zone was applicable to evaluate the energy of blast-induced seismic wave.

Abstract

Ribs effects on the heat transfer performance and cooling air flow characteristics in various aspect ratios (AR) U-shaped channels under different working conditions are numerically investigated. The ribs angle and channel orientation are 45° and 90°, respectively, and the aspect ratios are 1:2, 1:1, 2:1. The inlet Reynolds number changes from 1e4 to 4e4 and rotational speeds include 0, 550 rpm, 1,100 rpm. Local heat transfer coefficient, endwall surface heat transfer coefficient ratio and augmentation factor are the three primary criteria to measure channel heat transfer. Ribs increase the heat transfer area and improve heat transfer coefficient of ribbed surfaces significantly, especially in the 1st pass, while the endwall surface contributes more to channel heat transfer because of the larger area and relatively smaller heat transfer coefficient. The wide channel (AR=2:1) owns the better augmentation factor than the narrow channel (AR=1:2) and ribs heat transfer weight increases with an increase of the inlet Reynolds number. Rotating slightly reduces the ribs heat transfer weight in channel and the trailing surface in 1st pass is the main influence object of rotating.

Abstract

The numerical simulations are used to conduct the comparative study of pin-fins cooling channel and multi-impingement cooling channel on the heat transfer and flow, and to design the multi-impingement channel through the parameters of impinging distance and impingement-jet-plate thickness. The Reynolds number ranges from 1e4 to 6e4. The dimensionless impinging distance is 0.60, 1.68, 2.76, respectively, and the dimensionless impinging-jet-thickness is 0.5, 1.0, 1.5, respectively. The endwall surface, pin-fins surface, impinging-jet-plate surface are the three object surfaces to investigate the channel heat transfer performance. The heat transfer coefficient h and augmentation factor Nu/Nu0 are selected to measure the surface heat transfer, and the friction coefficient f is chosen to evaluate the channel flow characteristics. The impinging-jet-plate surface owns higher heat transfer coefficient and larger area than pin-fins surface, which are the main reasons to improve the heat transfer performance of multi-impingement cooling channel. Reducing the impinging distance can improve the endwall surface heat transfer obviously and enhance impingement plate surface heat transfer to some extent, decreasing the thickness of impinging-jet-plate can significantly increase its own heat transfer coefficient, which both all increase the cooling air flow loss.