11 resultados para Tianjin
Resumo:
s a signatory to the Boxer Protocol in 1901, Italy came into possession of the Tianjin concession, its only colonial possession in China. The Italian settlement was situated on the Hai River, and most of the land consisted of cemeteries and salt deposits. Italian administration of the settlement encountered many difficulties. Expropriation of land from the Chinese occupants was not easy, and it proved equally difficult to attract Italian investors. However despite the fact that Italian public opinion supported the abandonment of the concession, the Italian government was ultimately obliged to undertake a project for its urban development. Success in Tianjin became a national challenge for Italy, with the National Trust providing the necessary economic support. The history of the Italian settlement in Tianjin therefore sheds light on the politics of colonialism and on Italy's economic and political agendas at the turn of the twentieth century.
Resumo:
As the concept of engine downsizing becomes ever more integrated into automotive powertrain development strategies, so too does the pressure on turbocharger manufacturers to deliver improvements in map width and a reduction in the mass flow rate at which compressor surge occurs. A consequence of this development is the increasing importance of recirculating flows, both in the impeller inlet and outlet domains, on stage performance.
The current study seeks to evaluate the impact of the inclusion of impeller inlet recirculation on a meanline centrifugal compressor design tool. Using a combination of extensive test data, single passage CFD predictions, and 1-D analysis it is demonstrated how the addition of inlet recirculation modelling impacts upon stage performance close to the surge line. It is also demonstrated that, in its current configuration, the accuracy of the 1-D model prediction diminishes significantly with increasing blade tip speed.
Having ascertained that the existing model requires further work, an evaluation of the vaneless diffuser modelling method currently employed within the existing 1-D model is undertaken. The comparison of the predicted static pressure recovery coefficient with test data demonstrated the inherent inadequacies in the resulting prediction, in terms of both magnitude and variation with flow rate. A simplified alternative method based on an equivalent friction coefficient is also presented that, with further development, could provide a significantly improved stage performance prediction.
Resumo:
A new approach to determine the local boundary of voltage stability region in a cut-set power space (CVSR) is presented. Power flow tracing is first used to determine the generator-load pair most sensitive to each branch in the interface. The generator-load pairs are then used to realize accurate small disturbances by controlling the branch power flow in increasing and decreasing directions to obtain new equilibrium points around the initial equilibrium point. And, continuous power flow is used starting from such new points to get the corresponding critical points around the initial critical point on the CVSR boundary. Then a hyperplane cross the initial critical point can be calculated by solving a set of linear algebraic equations. Finally, the presented method is validated by some systems, including New England 39-bus system, IEEE 118-bus system, and EPRI-1000 bus system. It can be revealed that the method is computationally more efficient and has less approximation error. It provides a useful approach for power system online voltage stability monitoring and assessment. This work is supported by National Natural Science Foundation of China (No. 50707019), Special Fund of the National Basic Research Program of China (No. 2009CB219701), Foundation for the Author of National Excellent Doctoral Dissertation of PR China (No. 200439), Tianjin Municipal Science and Technology Development Program (No. 09JCZDJC25000), National Major Project of Scientific and Technical Supporting Programs of China During the 11th Five-year Plan Period (No. 2006BAJ03A06). ©2009 State Grid Electric Power Research Institute Press.
Resumo:
The radial vaneless diffuser, though comparatively simple in terms of geometry, poses a significant challenge in obtaining an accurate 1-D based performance prediction due to the swirling, unsteady and distorted nature of the flow field. Turbocharger compressors specifically, with the ever increasing focus on achieving a wide operating range, have been recognised to operate with significant regions of spanwise separated flow, particularly at off-design conditions.
Using a combination of single passage Computational Fluid Dynamics (CFD) simulations and extensive gas stand test data for three geometries, the current study aims to evaluate the onset and impact of spanwise aerodynamic blockage in radial vaneless diffusers, and how the extent of the blocked region throughout the diffuser varies with both geometry and operating condition. Having analysed the governing performance parameters and flow phenomena, a novel 1-D modelling method is presented and compared to an existing baseline method as well as test data to quantify the improvement in prediction accuracy achieved.
Resumo:
Germany, Italy and Japan were engaged in China from the turn of the 20th century to WWII. However, they formed an anti-Chinese alliance only at the final stage of their presence there, when Japan assumed an undisputed role of leader in the region. Despite its alliance with the Axis powers, Japan never implemented racial laws against the Jews in China. All of them took part in the Boxer Upraising suppression and received as a consequence extraterritorial rights and concessions. Moreover, Japan won the war against China in 1895 and transformed itself from a tributary country of China into an imperialistic power. It took possession of Taiwan and in the 1930s established a puppet government in Manchuria.Germany followed different route obtaining as indemnity for the murders of two missionaries the control of the Shandong province, which was later expanded thanks to the anti-Boxer coalition's victory. However, Germany lost all possessions when China entered WWI. The issue of Shandong was finally resolved at the Conference for Disarmament hold in Washington in 1921-2. Japan failed to gain ex-Germany territories. Finally, Italy arrived in the Far East at the turn of the century but was not very interested in the oriental colonialism to the same extent it was interested in Africa. Tianjin was its only concession in China, and it took almost a decade before a subvention to arrive from the Italian government for its development.In the 1920s and 1930s Germany and Italy engaged in successful diplomatic, commercial and military relationships with China. In fact, both were considered China's partners thanks to their experts at the service of the Chinese government. On the other hand, Japan position was opposite to them, because of its plans of aggression towards China which was to be transformed into “the natural extension” of the mainland. In 1935 Italy declared war on Ethiopia and abandoned the seat at the League of Nations. China interpreted the Italian aggression as the endorsement of Japan's politics towards China in Manchuria, and the relations between the two countries were broken off. After that Italy supported Wang Jingwei's puppet government during the Japanese occupation of China. Germany followed the same path in 1937, when it was evident that the Japanese were playing the leading role in the region, and decided to ally with Wang Jingwei too. Both Italy and Germany decided also to recognise the Manzhuguo and established diplomatic relations, definitively turning their backs on the old Chinese ally.The Rome-Berlin-Tokyo Axis sealed the alliance among the three countries, and it confirmed Japan as the leading power in the region. Nevertheless Japan did not apply the racial law against the Jews in China.
Resumo:
Current trends in the automotive industry have placed increased importance on engine downsizing for passenger vehicles. Engine downsizing often results in reduced power output and turbochargers have been relied upon to restore the power output and maintain drivability. As improved power output is required across a wide range of engine operating conditions, it is necessary for the turbocharger to operate effectively at both design and off-design conditions. One off-design condition of considerable importance for turbocharger turbines is low velocity ratio operation, which refers to the combination of high exhaust gas velocity and low turbine rotational speed. Conventional radial flow turbines are constrained to achieve peak efficiency at the relatively high velocity ratio of 0.7, due the requirement to maintain a zero inlet blade angle for structural reasons. Several methods exist to potentially shift turbine peak efficiency to lower velocity ratios. One method is to utilize a mixed flow turbine as an alternative to a radial flow turbine. In addition to radial and circumferential components, the flow entering a mixed flow turbine also has an axial component. This allows the flow to experience a non-zero inlet blade angle, potentially shifting peak efficiency to a lower velocity ratio when compared to an equivalent radial flow turbine.
This study examined the effects of varying the flow conditions at the inlet to a mixed flow turbine and evaluated the subsequent impact on performance. The primary parameters examined were average inlet flow angle, the spanwise distribution of flow angle across the inlet and inlet flow cone angle. The results have indicated that the inlet flow angle significantly influenced the degree of reaction across the rotor and the turbine efficiency. The rotor studied was a custom in-house design based on a state-of-the-art radial flow turbine design. A numerical approach was used as the basis for this investigation and the numerical model has been validated against experimental data obtained from the cold flow turbine test rig at Queen’s University Belfast. The results of the study have provided a useful insight into how the flow conditions at rotor inlet influence the performance of a mixed flow turbine.