【作者】 钟伟；

【导师】 明晓；

【作者基本信息】 南京航空航天大学 ， 流体力学， 2007， 硕士

【摘要】 本文对孔板、V锥、槽道流量传感器等几种节流装置进行了流场数值模拟,对槽道流量传感器和孔板进行了流量标定实验。二维轴对称数值模拟结果展示了节流装置流场的速度分布、压力分布、湍流强度分布、壁面摩擦应力分布等基本特征;揭示出节流装置的流出系数特性是摩擦损失、漩涡耗散和实际喉道宽度变化共同作用的结果;根据数值模拟结果对比分析表明,槽道流量传感器在重复性、来流适应能力、永久性压力损失、长期可靠性等方面较孔板和V锥具有优势。三维数值模拟结果展示了弯头流场的速度、压力和壁面摩擦系数的不对称分布,以及安装在弯头下游的节流装置流场的速度和压力分布。分析了上游弯头对节流装置流场的影响,认为槽道流量传感器的来流适应能力最强,V锥次之,孔板最差。流出系数标定实验发现槽道流量传感器的流出系数在某一雷诺数之后迅速转变为常数;上游安装单弯头的标定实验表明,弯头将导致槽道流量传感器出现正的测量误差,该误差的大小与弯头的安装角度有关,在0.56%~1.73%之间,而相同条件下孔板的误差则高达17.4%;永久性压力损失实验表明,槽道流量传感器的相对压力损失随着雷诺数的增大迅速下降至0.3以下,而孔板则高达0.7。更多还原

【Abstract】 In the present research, numerical simulations and calibration experiments are done on throttle devices such as orifice-plate, v-cone, and spindle.In the result of two dimensional simulations, the distribution of velocity, pressure, turbulence, and surface friction in the flowfield of throttle devices is showed. It is discovered that the characteristic of the discharge coefficient is determined by the action of friction loss, vortex dissipation, and width changing of the actual throat. The spindle represents more advantages than orifice-plate and v-cone in repeatability, adapting to coming streams, non-recovered pressure loss, and long-term reliability.In the result of three dimensional simulations, the asymmetric distribution of velocity, pressure, and surface friction in the flowfield of an elbow and throttle devices downstream is showed. The measurement error in throttle devices caused by an upstream elbow is discussed.It is found in calibration experiments that the discharge coefficient of a spindle turns rapidly to a constant in a certain Reynolds Number. A plus error appears when an elbow installed upstream the spindle. The magnitude of the error is related to the installation angle of the elbow, which is between 0.56% and 1.73%. As a contrast, the error in orifice-plate in the same condition reaches as high as 17.4%. The result of experiments on non-recover pressure loss shows that the relative pressure loss of spindle drops rapidly to 0.3 and lower when Renolds Number increases, however it is as high as 0.7 for orifice-plate.更多还原