铝板翅式换热器翅片表面性能的试验研究

目前,国内进行板翅式换热器设计时,直接采用日本神户钢铁公司的翅片表面性能曲线势必会导致板翅式换热器热力设计有较大的误差。为此,设计并搭建了一台翅式换热器翅片表面性能试验装置,对锯齿形、波纹形、百叶窗形3种常见的铝翅片表面进行了冷态和热态试验研究,测定翅片表面传热性能和摩阻损失曲线,得到了雷诺数Re与传热因子j、摩擦因子f的关系。试验结果表明,国产翅片的摩擦阻力与国外接近,甚至低于国外,而传热性能大约低10%;在Re>4000时,随着雷诺数的继续增大,国产翅片传热性能降低较快,这说明国产翅片的加工工艺、制造精度和材料冶金工艺等虽已接近国外先进水平,但还有待进一步改进。     

Exact and approximate analytic solutions of the nonlinear convective fin problem with temperature-dependent thermal conductivity

This article shows that the well-known nonlinear boundary value problem of the differential equation for temperature distribution of convective straight fins with temperature-dependent thermal conductivity is exactly solvable in an implicit form. Furthermore, an exact solution in an explicit form is derived. Also, an accurate analytic solution (series solution) is obtained by a new variation of the Adomian decomposition method.     

变导热系数对流-辐射-导热肋片的双重级数摄动解

应用正则摄动法研究一维直肋在导热系数随温度呈线性变化时的传热问题．在对流换热和辐射换热同时存在的条件下，以肋片材料的导热系数随温度变化的参数(E1)和肋片材料的黑度及导热系数的综合参数(E2)为两个摄动小参数，利用双级数的摄动展开得到了在绝对零度理想条件下肋片温度分布和肋效率的一组级数形式的解．     

Enhancement of convective cooling using oscillating fins

Tailoring the local flow field around a fin can substantially enhance the forced convection heat transfer from a conventional heat sink. A fin is set into oscillation leading to rupture of the thermal boundary layer developed on either side of the fin. This enhancement in heat transfer is demonstrated through an increase in the time-averaged Nusselt Number (Nu) on the fin surfaces. Nu has been found to be strongly dependent on the flow Reynolds Number (Re), the frequency and amplitude of the fin oscillations. A threshold amplitude and frequency is identified beyond which Nu improvements are observed for fixed Re.     

螺旋翅片管簇散热器优化设计

本文从理论上分析了自然对流方式下螺施翅片管簇散热器的翅高、翅厚、管径、翅间距，罩高对散热器的热工性能的影响．利用已有的经平板通道的自然对流换热公式，采用修正该公式中在极高度的方法及光滑圆管自然对流换热公式，给出了计算螺旋翅片管簇散热量的半理论计算方法．利用计算机分析了各影响因素对散热器换热量影响的程度；以金属热强度最大为优化目标，给出了该类型散热器的最佳结构参数族。     

减摇鳍-减摇水舱综合减摇实验装置的研究

采用了减摇鳍-减摇水舱综合减摇的数学模型，对综合减摇数学模型在实验装置上的实现方法进行了分析。通过用软件模拟船舶横摇阻尼力矩的方法可以实现台架模拟船舶的横摇运动，通过对船舶-水舱系统数学模型的分析，可用近似二项式替代的方法来简化船舶-水舱系统数学模型，并通过仿真选出了较理想的近似参数值，使综合减摇数学模型在实验装置上的实现成为可能。通过对综合减摇理论数学模型和综合减摇实验装置模型的仿真分析，可以看出两者有较好的相似性，说明用文中综合减摇实验装置来模拟综合减摇系统的实现方法是可行的。     

2D楔型舵的空泡流场特性研究

水下航行体的航行性能直接受其操纵舵的影响，为确保航行体在全沾湿以及超空泡航行状态时均具有良好的稳定性，该文采用理论数值方法详细分析比较了2种典型楔型舵翼型在不同航行状态下的空泡形态及其升／阻力系数的变化规律，研究结果表明，随着来流攻角的增大，阻力系数呈现先减小后增大的趋势，且大空泡数条件下2种楔型舵的舵效相当，但有平行后体时的楔型舵在小空泡数条件下具有较高的舵效，需合理选择楔型舵以确保航行体具有稳定的航行性能。     

Performance of symmetric polygonal fins with and without tip loss — A comparison of different methods of prediction

No analytical solution exists for estimating the efficiency of symmetric polygonal fins (SPFs) circumscribing circular tubes. Performance of such fins is conventionally determined from either of the two approximate techniques, namely, the equivalent annulus method and the sector method. The present work aims to judge the relative merits and applicability of these two methods critically. To this end, the results obtained from the approximate techniques have compared with those obtained from a semi‐analytical technique. It has been noted that, with the increase of the tip heat loss, the accuracy of prediction from any of the approximate methods decreases. For the sector method, a modification has been suggested. The prediction from the modified version of the sector method is always more accurate than that from the equivalent annulus method. It has been further illustrated that though the approximate techniques can be employed for the prediction of efficiency, they cannot be used to predict the tip temperatures accurately.     

等截面柱形直肋-维修正传热(近似解)方程及肋传热量的新的简化计算

针对一维经典肋传热方程及近似解的局限性，推出了等截面柱形直肋的一维修正肋传热方程及修正近似解。进一步针对工程中肋端传热时热量的简化计算法提出了一种新的更为精确的修正简化计算公式。数值比较结果表明：提出的公式不仅具有原经典公式相同形式及简洁性，而且使得肋根部热流率及各截面平均温度的计算精度有了显著的提高，并将公式的应用范围扩大至较大Bi数，这为肋片的工程设计优化和应用提供了更为准确而直观的求解方法。