Labyrinth seal construction influence on effectiveness of axial compressor stage

This High efficiency of an aircraft engine is particularly important for ensuring competitiveness. Improving overall efficiency can be achieved by increasing the level of efficiency of individual engine components and individual elements. Flow path seals can be considered as such elements. In the article, the effect of tightness of the flow path seal in the stage on the efficiency is considered. Most publications on research devoted by the seals in aircraft engines study the seals as a separate object. Only physical parameters are specified as input data for the design process. However, the certain relationship exists between the seal design and the stage parameters. For a more detailed and precise design, the seal must be designed both as separately and as part of the blade machine. It is the first point of scientific novelty of this article. The second point is that sealing is not considered in the traditional way. Usually, only classical types of seals are investigated. These are labyrinth, brush, face contact seals and others. However, in aircraft engines, the examples of using only one singular seal are rare. In this article, the sealing system is investigated. This system consists of two rim seals, two inter-seal cavities, and a labyrinth seal. To solve this problem, a three-dimensional calculation model together with a three-dimensional stage model were created. The variants with one, two, and three stages that are working together were also investigated. This study is necessary to explain the impact of a single seal not only on one stage but also on the entire compressor. This study was based on the design of an axial compressor with relatively low parameters. In modern compressors with high values of the total compression ratio, this effect will be much higher. It means that the results of the investigation can be used in the overall range of modern gas turbine machines. As a result of the study, the influence of the leakage value through the seal on the level of efficiency of one stage and a group of stages was determined. Whereas the calculating of the losses due to the vortex formation and air heating from rotation were also taken into account. In addition, the influence of other design parameters of the seal has been investigated. These parameters are the size of the gap, the radius of the seal position, the manufacturing tolerances, the number of pins, and their shape, the flow modes, and the geometric parameters of the interstitial cavities. The correctness of the conclusions was confirmed by comparison with the experimental data. The actual profiles of the compressor blades were used for the creating of the calculation models. The comparison was performed with the actual outflow characteristics of the compressor, that was obtained during its official tests. As a result of the comparison, an acceptable difference was obtained between the calculated and experimental results.