论文标题
压力损失及其在蒸汽驱动器中摄入过程中的效果的数值研究
Numerical Investigation of Pressure Losses and its Effect During Intake in a Steam Wankel Expander
论文作者
论文摘要
Wankel Steam扩展器比其他正排量机作为扩展设备具有许多优势。这是由于其高功率与重量比，紧凑，噪声较低，振动以及可能较低的特定成本，使其成为往复扩张器的优惠选择。在扩张室的入场室通过锅炉的蒸汽供应供电。本研究的目的是研究摄入过程中蒸汽压力损失的幅度及其对扩展器净功率输出的影响，范围从1200到3000 rpm不等。使用Python对扩展器的理论压力量循环进行热力学分析，然后在ANSYS Fluent 19.2中用于CFD分析。为从进气门端口的出口到转子外壳中的端口的流动域开发了三维模型，以不同的转子角度从入院到截止。进行计算以研究入院期间蒸汽的相关压降。不同转子角度的边界条件是从扩展器的理论压力量图的热力学模型中获得的，并从重建数据库获得了状态点值。通过使用文献中报道的相关性和表达式来比较通过分析方法获得的压降值来进行CFD模型的验证。对该扩展设备进行了彻底的性能分析，并计算了由于进气压损失而导致的功率输出损失。入院期间的这些损失改变了为给定压力比设计的实际扩展器的压力比，从而导致功率输出降低了20％至30％。据观察，功率输出损失的百分比随轴速度的增加而增加。
A Wankel steam expander has numerous advantages over other positive displacement machines as an expansion device. This is due to its high power to weight ratio, compactness, lower noise, vibration, and potentially lower specific cost making them a favourable choice over reciprocating expanders. Admission in the expander chamber occurs through rotary valves fed with steam supply from a boiler. The present study aims to investigate the magnitude of pressure losses of the steam during intake and its effect on the net power output of the expander over a range of rotational speed varying from 1200 to 3000 RPM. The thermodynamic analysis is carried out for the theoretical pressure-volume cycle of the expander using Python, which is then used for CFD analysis in Ansys Fluent 19.2. Three dimensional models are developed for the flow domain stretching from the exit of the intake valve port to the port in the rotor housing at different rotor angles ranging from admission to cutoff. Computations are performed to investigate the associated pressure drop of steam during admission. The boundary conditions at different rotor angles are obtained from the thermodynamic model of the expander's theoretical pressure-volume plot, and the state point values were obtained from the REFPROP database. Validation of the CFD models are carried out by comparing pressure drop values obtained through an analytical approach using correlations and expressions reported in literature. A thorough performance analysis of this expansion device is made and the loss in power output due to the intake pressure loss is calculated. These losses during admission change the pressure ratio across the actual expander designed for a given pressure ratio, leading to a reduced power output by a reasonable margin of 20 to 30%. It is observed that the percentage loss in power output increases with an increase in shaft speed.
