The effect of the tip gap size on the performance of a multistage axial compressor was studied by means of computational fluid dynamics (CFD). It was found that the performance of the compressor was very sensitive to the size of the tip gap. By increasing the gap size, the stall margin value, the total pressure ratio and the compressor efficiency reduced considerably. The flow field at the tip ...

A combination of theoretical and computational nonlinear analysis techniques are used to study the scenario of bifurcations responsible for the initiation of rotating stall in an axial ow compressor model. It is found that viscosity tends to damp higher-frequency modes and so results in a sequence of bifurcations along the uniform-ow solution branch to stall cells of diierent mode number. Lower...

T he increase of the thrust-to-weight ratio of modern gas-turbine engines results in higher loads and a reduced number of blades and stages for the compressor. The designer must ensure the acceptable performance of each compressor stage (efficiency and stable operating range) and control the rising risk of blade boundary layer separation. This can be obtained using passive or active control dev...

Axial flow compressors are subjected to demands for ever-increasing levels of pressure ratio at a compression efficiency that augments the overall cycle efficiency. However, unstable flow may develop in the compressor, which can lead to a stall or surge and subsequently to gas turbine failure resulting in significant downtime and cost to repair. To protect against these potential aerodynamic in...

Stall warning of axial compressor is very challenging and the existing margin not enough. A algorithm based on BP neural network fusion fuzzy logic proposed. Firstly, used for training recognition, next identification results are fused with reasoning to form result judgment time sequence, finally stall early realized. The simulation experimental data show that at all speeds least 0.1s in advanc...

Numerous experiments have been conducted on plunging Eppler 361 airfoil in a subsonic wind tunnel. The experimental tests involved measuring the surface pressure distribution over the airfoil at Re=1.5×105. The airfoil was equipped with Gurney flap(heights of 2.6, 3.3 and 5% chord) and plunged at 6cm amplitude. The unsteady aerodynamic loads were calculated from the surface pressure measurement...

An unsteady nonlinear and extended version of the Moore-Greitzer model is developed to facilitate the synthesis of a quasilinear stall vibration controller. The controller is synthesised in two steps. The first step defines the equilibrium point and ensures that the desired equilibrium point is stable. In the second step, the margin of stability at the equilibrium point is tuned or increased by...

Stall and surge are strong limitations in the operating range of compressors thus one major limits jet engine performance. A promising way to push stability limit compression machines is inject a small amount flow at blade tip alter physical mechanism responsible for stall onset. This study focuses on experimental performance such system. To do so, an axial compressor test bench was equipped wi...