盖板式预旋系统的压比和熵增特性

对预旋系统内的压力变化相关研究较少。基于理论分析、实验测量以及数值计算,对某盖板式预旋系统的压比及熵增特性进行研究。通过理论推导,对预旋系统内压比与无量纲温降的关系进行分析。在最高转速可达10000r/min的高转速实验台上,测量了转盘上的气流静压以及相对总温,进而获得压比及熵增特性。进行三维数值计算,将数值计算结果与实验结果进行了对比,并根据数值计算结果对预旋系统内的熵产分布以及各元件的熵增情况进行分析。结果表明:系统温降以及旋转马赫数大小决定了预旋系统的理想最大压比,而实际压比与理想压比的比值取决于系统内的熵增大小。采用数值计算以及实验测量所得结果对理论关系式进行了验证,最大偏差2.7%。旋转马赫数一定的条件下,随系统无量纲温降增大,系统压比逐渐减小。由于熵增影响,实测压比与理想压比最大相差约36%。预旋系统内的熵增主要发生在预旋腔静止壁面、接受孔前后、供给孔进口等气流旋转比发生剧烈变化的区域。预旋系统内主要元件的熵增随流量增大都呈逐渐增大的趋势,但接受孔处熵增最小值出现在喷嘴出口旋转比等于1左右时,流量过小或过大都会导致接受孔处熵增变大。

Pressure Ratio and Entropy Increment in a Cover-Plate Pre-Swirl System

There are few studies on the variation of pressure in pre-swirl system. This paper describes a combined theoretical, experimental, and computational study of the pressure ratio and entropy increment in a cover-plate pre-swirl system. The relation between the pressure ratio and non-dimensional temperature drop was deduced theoretically. In a test rig with rotational speed up to 10000r/min, the static pressure and relative total temperature were both measured on the rotor to get the pressure ratio and entropy increment of a pre-swirl system. 3D numerical simulations were conducted and the numerical results were compared with the experimental results. According to the numerical results, the entropy increment of each component and the distribution of entropy generation in a pre-swirl system were both studied. The results show that the ideal pressure ratio depends on non-dimensional temperature drop and rotating Mach number, and the ratio of the actual pressure ratio to the ideal pressure ratio depends on the entropy increment. The theoretical correlation was verified with numerical and experimental results. The difference is not greater than 2.7%. With a given rotating Mach number, the actual pressure ratio decreases with the increasing of non-dimensional temperature drop, and the maximum difference between the actual pressure ratio and the ideal pressure ratio is about 36%. Entropy generated mostly at this domain where the velocity changes acutely, including the downstream of pre-swirl nozzle, the receiver hole inlet, the downstream of receiver hole, and the inlet of feed hole. For most of the components in the pre-swirl system, entropy increment increases with the increasing of mass flow rate. However, for the receiver hole, entropy increment would be smaller when the nozzle outlet swirl ratio close to 1. Excesses or insufficient mass flow rate would make the entropy increment increase.