scholarly journals Research on the silver in the world flowing into Qing Dynasty

2019 ◽  
Vol 1 (1) ◽  
pp. 26-28
Author(s):  
Jun Wei

In the 80 years of foreign trade in the Qing Dynasty, the main flow direction of silver was from Spain and Britain to Qing Dynasty, which is one of the main contents; the other is the materials, process and variety design of the silver flowing into the Qing Dynasty.

Author(s):  
Kevin Tracy ◽  
Stephen P. Lynch

Abstract Shaped film cooling holes are used extensively for film cooling in gas turbines due to their superior performance in keeping coolant attached to the surface, relative to cylindrical holes. However, fewer studies have examined the impact of the orientation of the shaped hole axis relative to the main flow direction, known as a compound angle. A compound angle can occur intentionally due to manufacturing, or unintentionally due to changes in the main flow direction at off-design conditions. In either case, the compound angle causes the film cooling jet to roll up into a strong streamwise vortex that changes the lateral distribution of coolant, relative to the pair of vortices that develop from an axially oriented film cooling hole. In this study, Large Eddy Simulation (LES) using the Wall-Adapting Local Eddy Viscosity (WALE) model was performed on the publicly available 7-7-7 shaped film cooling hole, at two orientations (0°, 30°) and two blowing ratios (M = 1, 3). Laterally-averaged film effectiveness was largely unchanged by a compound angle at a blowing ratio of 1, but improved at a blowing ratio of 3. For both blowing ratios, the lateral distribution of film was more uniform with the addition of a 30° compound angle. Both wall normal and lateral turbulent convective heat transfer was increased by the addition of a compound angle at both blowing ratios.


2011 ◽  
Vol 134 (1) ◽  
Author(s):  
Helmut Sauer ◽  
Robin Schmidt ◽  
Konrad Vogeler

In this paper, results concerning the influence of chord length and inlet boundary layer thickness on the endwall loss of a linear turbine cascade are discussed. The investigations were performed in a low speed cascade tunnel using the turbine profile T40. The turning of 90 deg and 70 deg, the velocity ratio in the cascade from 1.0 to 3.5 as well as the chord length of 100 mm, 200 mm, and 300 mm were specified. In a measurement distance of one chord behind the cascade in main flow direction, an approximate proportionality of endwall loss and chord was observed in a wide range of velocity ratios. At small measurement distances (e.g., s2/l=0.4), this proportionality does not exist. If a part of the flow path within the cascade is approximately incorporated, a proportionality to the chord at small measurement distances can be obtained, too. Then, the magnitude of the endwall loss mainly depends on the distance in main flow direction. At velocity ratios near 1.0, the influence of the chord decreases rapidly, while at a velocity ratio of 1.0, the endwall loss is independent of the chord. By varying the inlet boundary layer thickness, no correlation of displacement thickness and endwall loss was achieved. A calculation method according to the modified integral equation by van Driest delivers the wall shear stress. Its influence on the endwall loss was analyzed.


2019 ◽  
Vol 865 ◽  
Author(s):  
Kevin Kevin ◽  
Jason Monty ◽  
Nicholas Hutchins

This paper quantifies the instantaneous form of large-scale turbulent structures in canonical smooth-wall boundary layers, demonstrating that they adhere to a form that is consistent with the self-sustaining streak instability model suggested by Flores & Jiménez (Phys. Fluids, vol. 22, 2010, 071704) and Hwang & Cossu (Phys. Fluids, vol. 23, 2011, 061702). Our motivation for this study stems from previous observations of large-scale streaks that have been spatially locked in position within spanwise-heterogeneous boundary layers. Here, using similar tools, we demonstrate that the randomly occurring large-scale structures in canonical layers show similar behaviour. Statistically, we show that the signature of large-scale coherent structures exhibits increasing meandering behaviour with distance from the wall. At the upper edge of the boundary layer, where these structures are severely misaligned from the main-flow direction, the induced velocities associated with the strongly yawed vortex packets/clusters yield a significant spanwise-velocity component leading to an apparent oblique coherence of spanwise-velocity fluctuations. This pronounced meandering behaviour also gives rise to a dominant streamwise periodicity at a wavelength of approximately $6\unicode[STIX]{x1D6FF}$. We further statistically show that the quasi-streamwise roll-modes formed adjacent to these very large wavy motions are often one-sided (spanwise asymmetric), in stark contrast to the counter-rotating form suggested by conventional conditionally averaged representations. To summarise, we sketch a representative picture of the typical large-scale structures based on the evidence gathered in this study.


Coatings ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 553 ◽  
Author(s):  
Muhammad Afzal Rana ◽  
Yasar Ali ◽  
Babar Ahmad ◽  
Muhammad Touseef Afzal Rana

This work explores the three-dimensional laminar flow of an incompressible second-grade fluid between two parallel infinite plates. The assumed suction velocity comprises a basic steady dispersal with a superimposed weak transversally fluctuating distribution. Because of variation of suction velocity in transverse direction on the wall, the problem turns out to be three-dimensional. Analytic solutions for velocity field, pressure and skin friction are presented and effects of dimensionless parameters emerging in the model are discussed. It is observed that the non-Newtonian parameter plays dynamic part to rheostat the velocity component along main flow direction.


Author(s):  
Jose M. Luna ◽  
Ricardo Romero-Mendez ◽  
Abel Hernandez-Guerrero ◽  
Jose C. Rubio-Arana

The flow structures in the cavities of parallel cross-corrugated surfaces, also called chevron geometry, are investigated in this work using an experimental visualization method. An angle of 45° between the corrugations and the main flow direction has been considered. Reviews show that a considerable amount of investigations, mainly experimental, of heat transfer and pressure drop for cross-corrugated plates has been performed, whereas for the flow field in the cavities has only been investigated numerically. The flow visualization experiments are performed inside a water tunnel using a wide range of the hydraulic diameter-based Reynolds number.


2013 ◽  
Vol 3 (1) ◽  
pp. 31-70 ◽  
Author(s):  
Patricia Sieber

Abstract This paper posits that the circulation of the earliest items of Chinese fiction in early modern Europe was indebted to the popularity of certain titles within the Qing-dynasty book market on the one hand and to the participation of educated Chinese in the process of purchase, selection, and translation on the other. It further argues that European translations deployed specific features of Chinese imprints in order to differentiate translations from the hugely popular pseudo-Chinese transcreations, thereby seeking to establish textual authority for a philologically grounded Chinese voice. The paper terms this convergence of conceptual, material, and social factors in producing transculturally mediated texts “biblioglossia,” in order to capture aspects of textuality neglected or obscured in standard discussions of “orientalism.”


2005 ◽  
Vol 127 (5) ◽  
pp. 888-896 ◽  
Author(s):  
Aroon K. Viswanathan ◽  
Danesh K. Tafti

Detached Eddy Simulation (DES) of a hydrodynamic and thermally developed turbulent flow is presented for a stationary duct with square ribs aligned normal to the main flow direction. The rib height to channel hydraulic diameter (e∕Dh) is 0.1, the rib pitch to rib height (P∕e) is 10 and the calculations have been carried out for a bulk Reynolds number of 20,000. DES calculations are carried out on a 963 grid, a 643 grid, and a 483 grid to study the effect of grid resolution. Based on the agreement with earlier LES computations, the 643 grid is observed to be suitable for the DES computation. DES and RANS calculations carried out on the 643 grid are compared to LES calculations on 963∕1283 grids and experimental measurements. The flow and heat transfer characteristics for the DES cases compare well with the LES results and the experiments. The average friction and the augmentation ratios are consistent with experimental results, predicting values within 10% of the measured quantities, at a cost lower than the LES calculations. RANS fails to capture some key features of the flow.


Author(s):  
Leif Littrup

The territory of the Qing dynasty was in 1840 still at its maximum, roughly 25 percent larger than the present Chinese territory and more than double the size of the previous Ming dynasty. The history of the Qing dynasty is about this expansion and how Han Chinese tradition and institutions interacted with a leadership dominated by ethnic or organizational minorities, the Manchus and other bannermen. It was a time of change in society and government that belies the still heard claim that it was an immobile empire both internally and in a world context. This article focuses mainly on government and political history; it touches on social and cultural history, but these are dealt with more extensively in other articles in the Oxford Bibliographies in Chinese Studies. The population probably doubled in the period, and many people may have experienced rising or at least adequate living standards. There were few technological breakthroughs in production, but rational application and expansion of existing methods to more land in combination with other economic measures secured a rise in production, at least until around 1800, aided by a government apparatus with qualifications and flexibility to solve problems that arose. The ethnic or organizational complexity of government administration may have helped to create a strong administration, but state finances were never strong enough to evade corruption and its threats to society. Foreigners arrived as before, Qing subjects went abroad, and the integration of China in the world and the world economy before the European powers started to intrude on Qing territory, both on the coast and the continental borders, is now accepted by most historians although it is always possible to find rhetoric, rules, and actions that, seen in isolation, may support the impression of an isolating empire.


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