溢洪道水流特性分析

溢洪道的控制段之后常设置收缩段,并且溢洪道的水流一般为急流,因此,在收缩段内将产生陡冲击波,使溢洪道内水流的流态复杂化。收缩段的水流特征应采用冲击波理论分析计算,只有正常陡槽段的水力计算才可采用能量公式。分析表明,由于收缩段和正常泄槽段的相对水位不同,将产生不同的水面衔接形式。大多数情况下,收缩段的陡冲击波控制溢洪道陡槽的过流能力与边墙高度。     

溢洪道水流特性分析

溢洪道的控制段之后常设置收缩段，并且溢洪道的水流一般为急流，因此，在收缩段内特产生陡冲击波，使溢洪道内水流的流态复杂化。收缩段的水流特征应采用冲击波理论分析计算，只有正常陡槽段的水力计算才可采用能量公式。分析表明，由于收缩段和正常泄槽段的相对水位不同，特产生不同的水面衔接形式。大多数情况下，收缩段的陡冲击波控制滋洪道陡槽的过流能力与边墙高度。     

一种改善溢洪道陡槽弯道水流流态的措施研究

水库溢洪道受其地形、地质条件限制,在陡槽段不得不设置弯道。针对云南省某水库溢洪道,通过水工模型试验研究,水流通过陡槽弯道后产生了不对称冲击波,水流分布极不均匀,水流流态紊乱,下游消能能力严重不足。为解决这些问题,经反复试验,最终在陡槽弯道段底部垂直布置了四道斜槛。采用这种工程措施,起到了消减急流冲击波,改善陡槽弯道水流流态,提高下游消能能力的良好效果,可为同类工程提供一定参考。     

圆弧形急流弯道的水流分析计算及设计

结合弥勒县虹溪排洪隧洞出口泄槽Ⅱ段需设弯道而产生急流冲击波的特点,通过对急流弯道中冲击波的形成分析计算,对排洪隧洞出口泄槽弯道上产生急流冲击波采取了相应的工程措施,保证了隧洞出口泄槽水流的平顺连接。虹溪排洪隧洞工程2007年运行至今,弯道运行较好,水流平顺流畅。     

斜槛法在消减弯道急流冲击波中的应用

泄水建筑物在陡槽段由于地形、地质条件等因素限制常设置有弯道，当水流通过时不可避免将产生急流冲击波，对工程安全运行极其不利，为此，实际工程须采取相应措施对之加以处理。本文围绕克纳普所提的斜槛法，结合桑株河水库、平定河水库、凤凰水库等工程实践，对斜槛设计及布置进行了归纳总结。实践表明：斜槛法的合理应用对消减弯道急流冲击波能起到显著效果。     

利用斜槛消减弯道急流冲击波的应用

泄水建筑物在陡槽段由于地形、地质条件等因素限制常设置有弯道,这种情况下,当水流通过时不可避免将产生急流冲击波,对工程安全运行极其不利,为此,实际工程须采取相应措施对之加以处理。本文围绕克纳普所提的斜槛法,结合桑株河水库、平定河水库、凤凰水库等工程实践,对斜槛设计及布置进行了归纳总结。实践成果表明:斜槛法的合理应用对消减弯道急流冲击波能起到显著效果。     

悬栅水流流场测试及消能分析

陡坡弯道急流产生的折冲水流会对水利工程的安全运行产生严重后果，采用悬栅、悬板栅“消、导”结合较好地解决了陡坡弯道急流冲击波的控制问题，用多普勒激光测速系统对不同悬栅形式的附近流场进行了测试，分析了悬栅的消能效果，通过比较矩形栅条和工字钢栅条的优劣，得出了栅条在陡槽上的最小间距和水面高度，     

弯曲扩散陡槽水工水力学研究

弯曲扩散陡槽作为输水系统中的连接段,其流态以急流冲击波为特征,与弯道环流一起,流况紊乱而凶险,无疑会引发水工建筑物的损坏。该文以弯曲扩散陡槽水力模型为研究平台,试验分析了急流的性状及其危害性,论述了改进衔接流态的方法,依据转变急流成为缓流衔接的整治原则,提出了分流墙与消能工优化组合的改良水工布置,实施后行水确认,其在各级输水工况的流态和模型的优良效果基本一致。试验研究还得到斜坡扩散水跃跃长实验式,并与平底等宽明渠水跃公式作了比较。     

一种布置形式复杂的溢洪道消能探讨

对一级陡槽段接缓坡转弯段再束窄变二级陡槽的溢洪道,如果不及时对陡槽段进行消能,高流速水流将在转弯边墙的偏转下,产生水流集中甚至出现菱形冲击波,危及下游安全.针对这种情况,提出了对一级陡槽段采用多级消力池,二级陡槽段采用挑流的消能建筑物型式,并通过水工模型试验研究表明,消能效果十分理想,可确保建筑物本身及下游的安全.     

皂火口水库溢洪道急转弯不良流态的消除

中小型水库旁侧溢洪道设计中常用陡槽及弯道把水流引导到一定位置消能,宣泄上游洪水流量。当水流为缓流转弯时,为使水流平顺、防止凹岸冲刷及产生大的水面横比降,弯道半径与渠道护面材科有关,当为土质时,一般要求为水面宽度的3～5倍以上。当水流为急流转弯时,为避免不利于工程的冲击波、过大的水面超高,通常是要求转弯     

TURBULENT OPEN CHANNEL FLOW SUBJECTED TO THE CONTROL OF A SPANWISE TRAVELING WAVE

Turbulent open channel flows subjected to the control of a spanwise traveling wave have been investigated by means of Direct Numerical Simulation(DNS).The objective of this study is to reveal the response of the near-wall and surface-influenced turbulence to the spanwise traveling wave control.Three typical frequencies of the spanwise traveling wave,i.e.,high-,middle-and low-frequency,corresponding to the exciting periods at 25,50 and 100,are considered to study the turbulence dynamics in the wall and surface regions.To elucidate the behaviors of turbulence statistics,some typical quantities,including the mean velocity,velocity fluctuations and the structures of turbulence fluctuations,are exhibited and analyzed.     

THE APPLICATION OF COKELET''''S WAVE THEORY IN THE CALCULATION OF WAVE-CURRENT FIELD

By using Cokelet's wave theory,the limiting wave height and the relative waveangular frequency in wave-current field were calculated in this paper.It is indicated by numeri-cal calculation that if the water depth is not too small,the result given by authors'calculationare very close to the results of limiting wave height by Dalrymple(1975)and to the data of rel-ative wave angular frequency by linear wave theory;but if water depth is rather small,thereare some discrepancy,     

ON THE FORMATION OF THE BULGE IN A SPILLING BREAKING WATER WAVE

The early stages of a spilling breaking water wave leading to the formation of a bulge on the forward face of the wave are investigated. In this study, simultaneous space-time measurements of the free-surface elevation of a spilling breaking water wave are recorded and analyzed. The analysis, carried out in the frame of reference moving with the crest of the wave,reveals that the formation of the bulge is due to the presence of a shock-like mode. In the previous frame of reference, the shock itself is unsteady but its (spatial) location is time independent and coincides with the "toe" of the bulge. As time increases, the shock undergoes a flip (a reflection symmetry) with respect to the midpoint of our time interval. Such a flip is responsible for an abrupt increase of the wave steepe-ness, which will lead to wave breaking at later times. Following these observations, we present a two-dimensional quantitative model which reproduces both the formation of the bulge and the sudden increase of the wave stee     

THE ANALYSIS OF INTRASEASONAL LONG ROSSBY WAVE SPEED IN THE SUBTROPICAL PACIFIC OCEAN

1. INTRODUCTIONLong Rossby waves are the main mechanis mwherebyinformation about one part of the oceanistransferred to another part and a nonequilibriumo-cean state adjusts to an equilibriumone . The studyon the beta views of long Rossby waves is an i m-portant aspect of ocean circulation. In a recentstudy , Chelton and Schlax[1]conducted a thoroughanalysis of the satellite alti meter data from thefirst 3 years TOPEX/POSEIDON mission. Theyfound two interesting properties of long Ro…     

HYDRODYNAMIC ANALYSIS OF SHORELINE OWC TYPE WAVE ENERGY CONVERTERS

1. INTRODUCTIONPrototypes of wave energy converters have been constructed, and many remain operational in offshore and coastal waters in a number of countries including Japan and China［1~5］ . Of these energy converters, which are based on different conc…     

ANALYTICAL RESEARCH ON THE WAVE DIFFRACTION OF ARC-SHAPED FLOATING BREAKWATERS

1. INTRODUCTIONBreakwaters are generally constructed for thedissipation and reflection of incident wave energyin order to decrease the wave height to protect thecoast against the erosion and to decrease the forceacting on the coastal structures . Compared…     

APPLICATION OF MAXIMUM ENTROPY PRINCIPLE METHOD TO THE STUDY OF WAVE CLIMATE STATISTICAL CHARACTERISTICS

The Maximum Entropy Principle (MEP) method is elaborated, and the corresponding probability density evaluation method for the random fluctuation system is introduced, the goal of the article is to find the best fitting method for the wave climate statistical distribution. For the first time, a kind of new maximum entropy probability distribution (MEP distribution) expression is deduced in accordance with the second order moment of a random process. Different from all the fitting methods in the past, the MEP distribution can describe the probability distribution of any random fluctuation system conveniently and reasonably. If the moments of the random signal is limited to the second order, that is, the ratio of the root-mean-square value to the mean value of the random variable is obtained from the random sample, the corresponding MEP distribution can be computed according to the deduced expression in this essay. The concept of the wave climate is introduced here, and the MEP distribution is applied to fit the probability density distributions of the significant wave height and spectral peak period. Take the Mexico Gulf as an example, three stations at different locations, depths and wind wave strengths are chosen in the half-closed gulf,the significant wave height and spectral peak period distributions at each station are fitted with the MEP distribution, the Weibull distribution and the Log-normal distribution respectively, the fitted results are compared with the field observations, the results show that the MEP distribution is the best fitting method, and the Weibull distribution is the worst one when applied to the significant wave height and spectral peak period distributions at different locations, water depths and wind wave strengths in the Gulf. The conclusion shows the feasibility and reasonability of fitting wave climate statistical distributions with the deduced MEP distributions in this essay, and furthermore proves the great potential of MEP method to the study of wave statistical properties.     

提高超短波中继站可靠性的经验和体会

超短波水情自动测报系统由于通信可靠、技术成熟而在国内普遍应用，中继站是整个系统的重要环节，是确保系统正常运行的关键，要求其可靠性高。文中结合天鹅山中继站的信道质量、抗干扰能力、防雷措施和电源系统4个方面研究了影响可靠性的因素，并提出了改进及控制措施。     

STUDY OF NONLINEAR LONG WAVE APPOXIMATION IN UNIFORM CHANNELS VIA HAMILTONIAN STRUCTURE

ＳＴＵＤＹＯＦＮＯＮＬＩＮＥＡＲＬＯＮＧＷＡＶＥＡＰＰＯＸＩＭＡＴＩＯＮＩＮＵＮＩＦＯＲＭＣＨＡＮＮＥＬＳＶＩＡＨＡＭＩＬＴＯＮＩＡＮＳＴＲＵＣＴＵＲＥ￥ＸｕＸｉｎ－ｓｈｅｎｇ；ＺｈｏｎｇＷａｎ－ｘｉｅ；ＬｕＹｕ－ｌｉｎ（ＩｎｓｔｉｔｕｔｅｏｆＥｎｇ...     

NUMERICAL STUDY ON EFFECT OF WAVING BED ON THE SURFACE WAVE

1. INTROUCTION There have been lot of researches on the effect of the bottom on the surface wave, in which, most of them involved the fixed bottom with concave, convex, or periodical shapes [1-3]. It seems that very few ones on waving bed are available up…