Session: 31-05 Compressor Design

Paper Number: 127447

127447 - Study on Integrated Through-Flow Method for Variable Cycle Compression System 

Variable cycle engine (VCE) is one of the ideal power units for advanced multipurpose aircraft. The addition of bypasses and adjustable mechanisms in the compression system enables the VCE to adjust the mass flow distribution according to the flight mission, expanding the flight envelope. However, this also leads to strong aerodynamic coupling and complex matching relations between components.

Through-flow design and analysis are important steps in engine development to provide the proper meridional shape and blade section parameters for compression system. An integrated through-flow design and analysis method for the compression system of double bypass variable cycle engine was proposed. In this method, pairs of split streamlines and overlapping calculation planes were set up to ensure the continuity of flow parameters, realizing integrated coupling calculation of the front fan, the rear fan or core driven fan stage, and the compressor. It could take into account the aerodynamic coupling between components in iterations and solve the matching problem of the variable cycle compression system in preliminary design. It was also proven to have great practical value that the errors of flow rate, pressure ratio and efficiency calculated by the through-flow program were between 0.5% to 2.0%, as shown in verification results of several highly loaded compressors and variable cycle compression systems.

Then, through-flow design of a variable cycle compression system with front-and-rear-fan configuration was carried out by using the above method, with two different layout forms of adjustable guide vane compared. It was found that both of the layout forms, one with a front fan with an adjustable stator and the other with a rear fan with an adjustable inlet guide vane, could satisfy the design specifications. However, the former reduced the weight of the compression system, but the operation point of the front fan would change with the camber angle of the stator blade, while the latter could adjust the bypass ratio without affecting the operating condition of the front fan, but brought disadvantages in weight and rotor dynamics.

Finally, the influence of the bypass ratio of the second bypass on the performance of the variable fan system was studied based on the layout of front fan with an adjustable stator. By comparing the influence weights of the swirl term, the streamline slope term, the streamline  curvature term, the blockage term, and the axial and radial component terms of circulation increment on the total derivative of static pressure with respect to the radial coordinate in the radial equilibrium equation under different bypass ratios, and combining this with the three-dimensional CFD results, the mechanism of how mass flow distribution and guide vane control affect the performance of the variable fan system was analyzed, to provide references for matching design of the compression system of VCE.

Presenting Author: Shuying Zhang Institute for Aero Engine, Tsinghua University

Presenting Author Biography: The presenting author is pursuing a Ph.D in Institute of Aero Engine, Tsinghua University, and is engaged in general design of aero engine, aerodynamic design and flow mechanism analysis of fan and compressor.

Authors:

Shuying Zhang Institute for Aero Engine, Tsinghua University
Teng Fei Institute for Aero Engine, Tsinghua University
Jiabin Li Institute for Aero Engine, Tsinghua University
Lucheng Ji Institute for Aero Engine, Tsinghua University