چكيده به لاتين
One of the main challenges in designing compressors, particularly aviation industry’s compressors, is the aerodynamic flow instability. Thus, one of the most crucial design considerations is to consider the sufficient stall safe margin in circumstances where unfavorable boundary conditions are exerted to the compressor. In this research, a method called precursor-suppressed stall using the casing treatment is employed. In such a method, the safe margin achieved with the casing treatment can be evaluated by creating a number of precursor-suppressed stalls. Firstly, an appropriate numerical method is presented in order to determine the stall inception. Then, effects of the casing treatment on the compressor performance are assessed. The performance of the casing treatment in different percentages of the exposure of the rotor’s axial chord (33.3, 43.4 and 53.5%) is investigated through experimental tests. Two types of casing treatment are evaluated for aforementioned three exposure percentages. The best results in terms of the compressor performance were achieved for the 53.5% exposure of rotor’s axial length. The recessed vane casing treatment leads to significant stall margin improvement, without sacrificing the efficiency. Stall formation and subsequently the compressor performance strongly depend on the type of casing and the exposure percentage of the axial chord of rotor’s blade.
Most flow instabilities in compressors occur as rotating stalls. In fact, a rotating stall is composed of one or more stall cells which are able to cause a rapid or slow compressor failure, depending on the rotational speed of blades. Thus, the stable region for the compressor performance is determined in order to evaluate the meshing quality of the computational domain. Then, the steady-state numerical simulation of flow is conducted for the first stage with inlet guide vanes. The comparison can reveal an acceptable agreement between experimental and simulation results.
