Numerical and Experimental Investigation of Inter-stage Bleed in Axial Compressors of Industrial Gas Turbine

To provide a theoretical basis for the compressor bleed system design, this paper uses numerical simulation and rig tests to evaluate the influence of bleed system design parameters on bleed performance. The research focuses on a multistage axial compressor of a real industrial gas turbine. Through numerical simulations, the complex three-dimensional flow in the bleed system is analyzed. It is found that at high bleed rates, the pressure loss is mainly in the bleed annular cavity and off-take duct, accounting for over 80% of the total loss. The bleed annular cavity design affects the jet in the cavity and flow loss in the off-take duct. There is an optimal axial position for the off-take duct inlet to minimize pressure loss. When the high-speed jet from the bleed slot outlet faces the off-take duct inlet center directly, the circumferential static pressure non-uniformity is the worst. Compared to the optimal axial position, the static pressure non-uniformity at the throat increases by nearly 40%, revealing the sensitivity of bleed systems parametric design to the flow field's circumferential non-uniformity. The bleed annular cavity impacts the mainstream flow field's circumferential uniformity differently under various bleed system designs. A well-designed bleed system can prevent non-uniform inter-stage bleed from causing significant unit performance degradation; however, it still affects the unit's stall or surge characteristics.