Session: 31-02 Compressor Design

Paper Number: 152143

Analytical Study on the Influence of Stage-Wise Distribution of Parameters on the Performance of a Multi-Stage Axial Compressor 

When designing axial compressors for various purposes, obtaining the required compressor performance plays a major role. The compressor performance is the dependence of various performance parameters of the axial compressor on the operating mode. Wide application of this type of compressors both in aviation and ground equipment, obtaining preliminary performance at the design stage is one of the most important factors. This makes it possible to reduce the cost of designing the compressor and, as a result, increase its reliability and predictability of the obtained performance during its operation. The necessary distribution of parameters at the initial design stage helps to create a compressor with specified parameters in off-design modes or find the most optimal design of a multi-stage axial compressor. This is often necessary when designing aircraft engines, since the engine has several operating modes that are most important for flight, and this indicates several critical operating modes of the axial multi-stage compressor during engine operation. The same requirements apply to multi-stage compressors of gas turbine engines, which are used as power plants in stationary applications and for marine power and propulsion systems. In the industry, this approach will reduce energy costs for gas combustion, which will have a positive effect on the environmental friendliness of their operation.

At the initial design point, a large number of solutions can be obtained for the design of a multi-stage axial compressor and the distribution of parameters among the compressor stages.Often, practitioners of compressor aerodynamic design use well-entrenched “rules of good practice” to specify the correct parameters or parameter distributions. Some compressor design computer codes and practices enable the designer to perform a design space exploration to elucidate availability of design choices for the parameters of interests. However, the central aspect of the effect of such choices on the design point and off-design operation of the compressor has not been heretofore described in the open literature. The maximum efficiency criterion can be decisive only if the compressor is single-mode and will always operate at the design point. But even a change in atmospheric conditions will change the compressor operating mode. This reduces the importance of maximum efficiency at the design point. The compressor can have high efficiency values ​​at the design point, but not operate due to surge or high-frequency oscillations at the required off-design condition. It may not produce the required parameters at this condition.

This paper considers is devoted to the study of the influence of compressor stage specific work of a multi-stage compressor, the kinematic degree of reactivity and the shape of the flow path of the compressor on its performance. An in-house developed streamline 2D simulation code is used to design and analyze a large sample size of viable compressors. An integrated workflow automation tool is also utilized to synthesize, analyze, and post-process the data.

The objects of the study were projects of 3 standard sizes of medium-load 8-stage axial compressors with constant tip, middle and hub diameters. They had the same total pressure at compressor inlet, total temperature at compressor inlet, pressure ratio, rotational speed, number of stages, mass flow rate. Work distribution is constant by stages. These 3 projects were taken as initial. At the next stage of the study, the diameter dimensions, the number of blades in the stages and the axial speeds of the compressors were additionally recorded. Then, changes were made in the design point of the distribution of the kinematic degree of reactivity and specific work by compressor stages. After obtaining a new design for each compressor, performance maps were calculated at several rotor speeds. The total number of designed compressors for the final analysis exceeded 300 thousand.

The influence of these parameters on the compressor performance at lower and higher rotation speeds different from the design point is shown. Recommendations are given for the primary distribution of these parameters to obtain the required compressor performance in off-design modes.

Presenting Author: Vlad Goldenberg SoftInWay, Inc.

Presenting Author Biography: Vlad Goldenberg is an engineering manager at SoftInWay. His responsibilities include oversight of internal product development and commercial and government R&D projects. His interests are in the thermodynamics and fluid dynamics of advanced practical systems.

Authors:

Oleh Dehtiarov SoftInWay Switzerland GmbH
Vlad Goldenberg SoftInWay, Inc.
Ievgen Rublevskyi SoftInWay UK Ltd.
Leonid Moroz SoftInWay, Inc