As the gas temperature increasing, intricate cooling structures must be applied to the turbine blade, where film cooling is a major one. To continuously improve the film cooling efficiency, adopting a reasonable assessment method is particularly important. Adiabatic film cooling effectiveness η is a widely employed one while neglecting heat transfer in the solid domain. Aiming at its limitations in engineering, film cooling under non-adiabatic conditions were analyzed. The phenomenon of heat flux backflow in the solid domain was revealed, then a dimensionless design indicator: film absolute coverage coefficient—ζ, also a novel assessment method based on it was proposed. Furthermore, flow and heat transfer numerical analyzing of film cooling with different 3D inclination angles—γ and β were carried out employing these methods. The results exhibited the phenomenon of gas overheating and the notch of film absolute coverage area, which is usually ignored in adiabatic analysis. In addition, the effectiveness of the 3D inclination film cooling and the influence of angle γ and β was analyzed by the intermediate variables n and f extracted from the film absolute coverage area. The novel methods achieved in solving a typical film cooling issue, which predicted their advantages of turbine blade design under actual engine operating conditions.

Reducing the internal flow resistance of turbine blades can improve the overall efficiency of aero engines. To address the issue of the large internal flow losses in traditional horizontal exhaust slots for trailing edge cooling, structure of radially tilted trailing edge slots was proposed in previous work, and the flow resistance reduction ability of the novel scheme was investigated through numerical simulations under typical engine working conditions. Building on this, this research aimed to investigate the flow resistance of both novel and traditional schemes under ordinary pressure conditions through a combination of experimental and numerical methods. The results indicated that the tilted scheme exhibited a reduction in total pressure loss of approximately 5.7–9.1

In order to understand the characteristics and relationships between indoor and outdoor PM2.5 during the heating period of 2014 in Beijing, the investigation of PM2.5 and associated species including organic and elemental carbon (OC/EC), water soluble ions, metal elements and trace organic matter (OM) were undertaken at a residential apartment. The average PM2.5 concentration was 55.2 ± 47.3 µg m−3 for indoor and 100.4 ± 82.1 µg m−3 for outdoor, and the indoor PM2.5 was found to be mainly from outdoors. OM and (NH4)2SO4 were the dominated components of PM2.5, accounted for 71.5

The Vaneless Counter-Rotating Turbine (VCRT) is a novel aerodynamic layout that eliminates the guide vanes of the second stage, resulting in reduced axial size and weight, also decreased aerodynamic losses associated with them. Motivated by these advantages, a power turbine of this type was designed in this paper for a small aircraft with counter-rotating propfan. Firstly, the entire engine thermodynamic cycle was designed, and obtained the requisite parameters of the power turbine. Furthermore, the velocity triangle method was employed to the aerodynamic design of the VCRT. Three-dimensional simulation was performed at the design-point, and the performance showed that the total efficiency was 84.28

针对传统水平排气劈缝结构流动损失大的问题,提出了径向倾斜排气的设计思想,并围绕其进一步提出了直线式和曲线式两种倾斜劈缝结构.基于数值仿真研究了其内部流场,揭示了倾斜劈缝可减小冷气转折角,抑制旋涡产生,使流动更加平缓,从而减小流阻的机理.通过与水平劈缝的对比分析,初步验证了两种新型劈缝结构使总压损失分别降低了约10％～12％和13％～15％.进一步考虑了燃气外流与冷却气掺混过程对劈缝内流动的影响,仿真结果同样印证了倾斜劈缝对于内流减阻能力的提高.但同时也发现了此类倾斜射流导致掺混损失增大的现象,通过给出两类劈缝结构的涡轮叶栅整体流动损失变化规律为叶片综合性能优化提供了参考.

先进航空发动机中高耐温能力涡轮叶片通常要以增加冷却系统的流动阻力来提高冷却效果,但由此导致的二次流系统损失增大可能会引起整机性能的下降.研究了先进涡轮叶片中典型层板冷却结构的内部流动损失产生机理,并针对性地提出两种(进/出气孔平行式和交叉式)低流动阻力的蜂巢式冷却结构.基于三维数值仿真方法研究了其流动特点和损失特性,并揭示了该结构可以显著减小通道内气流转折角度、抑制旋涡产生和避免多股气流对撞的减阻强化机理.通过与典型层板结构的对比分析,初步验证了在相同的结构无量纲参数和流量下,两蜂巢式冷却结构的总压损失分别可降低65％～66％和67％～69％,在高推重比航空发动机涡轮叶片冷却设计上具有较好的应用前景.

To understand the removal and transformation behaviors of unconventional air pollutants (polycyclic aromatic hydrocarbons, heavy metals and carbonyl compounds) in the flue gas in cement kiln-end facilities, including SP boiler, a slide stream SCR-DeNO(x) system, raw mill and baghouse filter, the gas and particle matter samples at the inlets and outlets of each kiln-end installation were collected and the contents of the unconventional air pollutants were measured. The results showed that the concentrations of the polycyclic aromatic hydrocarbons (PAHs) in particulate and gas-phase, heavy metals in the particulate matter were 17.5 mu g m(-3), 48.7 mu g m(-3) and 3113.1 mu g m(-3) at the inlet of the SP boiler, and decreased to 0.6 mu g m(-3), 17.7 mu g m(-3) and 39.7 mu g m(-3), respectively, while the concentrations of carbonyl compounds in gas-phase increased from 1988.5 mu g m(-3) to 2844.5 mu g m(-3) after flue gas successively passed through the kiln-end facilities. The cooling of flue gas and the precipitation of coarse particulate matter in the SP boiler resulted in a significant decrease of PAHs concentration in both gas-phase and particulate-phase, as well as the heavy metal concentration in the particulate-phase, while the SP boiler hardly had any influence on the removal and transformation of carbonyl compounds. Grinding and heat exchange in the raw mill accelerated the volatilization of compounds with the low boiling point in the raw meal, which increased concentrations of gas-phase PAHs and carbonyl compounds. When flue gas passed through the baghouse filter, almost all particulate-phase PAHs, heavy metals and most of the gas-phase PAHs, were removed while the carbonyl compounds concentration maintained unchanged. Furthermore, some portion of gas-phase PAHs and carbonyl compounds were removed by the SCR-DeNO, system. (C) 2020 Elsevier Ltd. All rights reserved.

To understand the atmospheric particulate pollution characteristics of cities in different sizes and regions, PM10 and PM2.5 were simultaneously collected in three cities: Beijing, China, Islamabad, Pakistan and Suning, China, in summer (2016) and winter (2017), respectively. The associated species including carbonaceous, metal elements and water soluble ions were analyzed. Both PM10 and PM2.5 concentrations in winter are higher than those in summer in three cities. In Beijing, OM, NH4NO3 and (NH4)2SO4 are the main components, the PM2.5/PM10 ratio is the highest among three cities, and the NO3−/SO42− ratio is lower than that in Islamabad in winter, suggesting that coal-fired process contributed more in Beijing. In Islamabad, the main components of PM10 and PM2.5 are crust and OM. The average concentrations of both Ca and Na in PM10 are higher than those in Beijing and Suning, indicating that the soil dust may be one of main air pollution sources in Islamabad. The concentrations of OC in both PM10 and PM2.5 in Islamabad are in relatively high level in summer, which indicates that more secondary organic aerosols are formed in summer in Islamabad. The highest PM10 and PM2.5 concentrations occur in Suning and the chemical composition of PM2.5 in Suning is similar to that in Beijing whether it is summer or winter, and the proportion of EC in Suning is higher than that in the other two cities in both PM10 and PM2.5, which are attributed to atmospheric pollutants transport from the surrounding cities and the diesel vehicle emission.

To understand the effects of co-processing sewage sludge in the cement kiln on non-criterion pollutants emissions and its surrounding environment, the flue gas from a cement kiln stack, ambient air and soil from the background/downwind sites were collected in the cement plant. Polycyclic aromatic hydrocarbons (PAHs) and heavy metals of the samples were analyzed. The results show that PAHs in flue gas mainly exist in the gas phase and the low molecular weight PAHs are the predominant congener. The co-processing sewage sludge results in the increase in PAHs and heavy metals emissions, especially high molecular weight PAHs and low-volatile heavy metals such as Cd and Pb in the particle phase, while it does not change their compositions and distribution patterns significantly. The concentrations and their distributions of the PAHs and heavy metals between the emissions and ambient air have a positive correlation and the co-processing sewage sludge results in the increase of PAHs and heavy metals concentrations in the ambient air. The PAHs concentration level and their distribution in soil are proportional to those in the particle phase of flue gas, and the co-processing sewage sludge can accelerate the accumulation of the PAHs and heavy metals in the surrounding soil, especially high/middle molecular weight PAHs and low-volatile heavy metals.

Phthalates (phthalates esters, PAEs) are ubiquitous contaminants in various indoor and outdoor environment. Exposure to PAEs exerts adverse effects on human health. Seasonal variations of air phthalate concentrations and paired indoor and outdoor air phthalate level are rarely known. In this study, six priority phthalates in PM2.5 were investigated in three indoor sites (a students' dormitory, a residential apartment and an office) and one outdoor site in Beijing, China across four seasons. PM2.5 samples were collected at indoor and outdoor environment simultaneously. Total PAEs in four sites were 468 ng/m(3) (range: 9.52-1460 ng/m(3)), 498 ng/m(3) (range: 11.2-4790 ng/m(3)), 280 ng/m(3) (range: 4.08-1060 ng/m(3)), and 125 ng/m(3) (range: 4.10-4000 ng/m(3)), respectively. DBP and DEHP were the most abundant PAEs across the four sampling sites, accounting for 76.3%-97.7% of the total PM2.5-bound PAEs. Obvious seasonal variation of total PAEs was observed. PAEs concentrations were weakly or poorly correlated with PM2.5 levels. Indoor DBP and DEHP concentrations were much higher than those of outdoor, suggesting the importance of indoor DBP and DEHP sources. Principal component analysis revealed that cosmetics and personal care products, plasticizer and PVC products may be important sources for indoor PM2.5-bound PAEs. Daily intakes of PAEs via inhalation for infants, student, and office-workers were 5.0, 0.8 and 0.9 mu g/(kg-bw.day), respectively according to human exposure estimation. (C) 2018 Elsevier Ltd. All rights reserved.

Three indoor (residential home, dormitory, and office) and one outdoor concentrations of PM2.5-bound Polycyclic aromatic hydrocarbons (PAHs) were analyzed in Beijing across four seasons. The highest and lowest concentration of total PAHs for outdoor appeared in winter and in summer with averages of 200.1 and 9.1ng/m3 respectively. The seasonal variations of total PAHs in three indoor sites were the same as outdoor. The correlation analysis between the indoor and outdoor samples showed that the annual mean I/O ratios of total PAHs in the three sites were lower than 1. Source apportionment showed vehicle exhaust, coal combustion, and biomass burning were the major contributors of indoor and outdoor PM2.5-bound PAHs. Indoor source, such as camphor pollution, was identified in the dormitory, while camphor pollution and cooking sources were identified in the residential home. The annual averages of Benzo[a]pyrene equivalent concentration (BaPeq) were 7.6, 7.8, 7.7 and 12.7ng/m3 for the dormitory, office, residential home and outdoor samples respectively, far higher than the annual limit of 1ng/m3 regulated by European Commission. Life lung cancer risk (LLCR) in four sites across four seasons were over the acceptable cancer risk level, showing the cancer risk were at a high level in both indoor and outdoor sites in Beijing, and its level in indoor sites was much lower than in the outdoor site. The health risk assessment indicated the level of PAHs cancer risk on human for three indoor sites were similar. The results call for the development of more stringent control measures to reduce PAHs emissions.

The effects of co-processing sewage sludge in cement kiln on NOx, NH3 and PAHs emissions were systematically investigated in a cement production line in Beijing. The results show that co-processing the sewage sludge was helpful to reduce NOx emission, which primarily depends on the NH3 amount released from the sewage sludge. Meanwhile, NOx and NH3 concentrations in the flue gas have a negative correlation, and the contribution of feeding the sewage sludge to NOx removal decreased with the increase of injection amount of ammonia water in the SNCR system. Therefore, it is suggested that the injection amount of ammonia water in SNCR system may reduce to cut down the operating costs during co-processing the sewage sludge in cement kiln. In addition, the emission of total PAHs seems to increase with the increased amount of the sewage sludge feeding to the cement kiln. However, the distributions of PAHs were barely changed, and lower molecular weight PAHs were mainly distributed in gaseous phase, accounted for the major portion of PAHs when co-processing sewage sludge in cement kiln.