Axial compressor

About: Axial compressor is a research topic. Over the lifetime, 12035 publications have been published within this topic receiving 127766 citations.

System for cooling a gas turbine by bleeding air from the compressor

Abstract: A system for cooling a gas turbine by bleeding air from the compressor and channeling the air at the center of the engine towards the turbine in order to cool it. The air is bled from the plane of the disc bearing the blades of the compressor, said disc having radial ducts for the flow of the air. The invention is utilized in gas turbine engines to cool the turbine.

The Periodical Interaction of the Tip Clearance Flow in the Blade Rows of Axial Compressors

Abstract: Current models on the tip clearance flow in turbomachines only describe the time-averaged behaviour of the flow structures. However, the real tip clearance flow is periodically fluctuating in time. This fact has to be considered for the design of turbomachine bladings especially with regard to blade vibrations and tip clearance noise.Detailed experimental investigations on the time-resolved behaviour of the flow in the rotor blade tip region were carried out in a four-stage low-speed research compressor. A strong time-periodic interaction of the blade tip vortices of adjacent blades can be shown for relatively large tip clearance of the rotor blades for operating points near the stability limit of the compressor. The resulting flow pattern, which frequency is not related to the rotor frequency, moves along the blade row. It can be described as a multicell configuration with strongly fluctuating cell number and size. The structure and propagation of the flow instability can be summarized in a model of the periodic fluctuating tip clearance flow (Mailach et al., 2000).Additional experiments were carried out in a straight cascade to improve the understanding of this flow phenomenon. It can be shown by means of time-resolved measurements that the same disturbance exists for comparable inlet flow conditions in the blade tip region of the cascade. Flow visualizations show that the blade tip vortex is strongly fluctuating and moves sometimes ahead of the leading edge of the adjacent blade. The result of this is a short-lengthscale flow pattern, which is propagating along the blade row. These experiments confirm the model of the time-periodic tip clearance flow proposed for compressors. A Strouhal-number for the estimation of the frequency of the flow fluctuation will be presented, which includes both design and aerodynamic parameters.Copyright © 2001 by ASME

Turbojet aero engines having means for engine component cooling and compressor control

Abstract: This invention relates to gas turbine engines, and, more particularly, to multishaft turbojet aero engines having a plurality of compressors and turbines, in which air is bled from one or several compressors in the engine for cooling engine components and for providing a seal between the rotary and stationary assemblies of the several rotor systems, and in which means are additionally provided for compressor control.

Control-Oriented High-Frequency Turbomachinery Modeling: Single-Stage Compression System One-Dimensional Model

Abstract: A one-dimensional unsteady compressible viscous flow model of a generic compression system previously developed by the authors is applied to a multistage axial compressor experimental rig configured for single-stage operation. The required model parameters and maps are identified from experimental data. The resulting model is an explicit system of nine first-order ODEs. The model inputs are compressor speed, nozzle area, compressor discharge bleed area, plenum bleed area, inlet total pressure and entropy, and nozzle and bleed exit static pressures. The model and experimental data are compared with respect to both open-loop uncontrolled and closed-loop controlled behaviors. These comparisons focus on (i) forced transients and (ii) global nonlinear dynamics and bifurcations. In all cases the agreement between the model and experimental data is excellent. Of particular interest is the ability of the model, which does not include any hysteretic maps, to predict experimentally observed hysteresis with respect to the onset and cessation of surge. This predictive capability of the model manifests itself as the coexistence of a stable equilibrium (rotating stall) and a stable periodic solution (surge) in the model at a single fixed set of system input values. Also of interest is the fact that the controllers used for closed-loop comparisons were designed directly from the model with no a posteriori tuning of controller parameters. Thus, the excellent closed-loop comparisons between the model and experimental data provide strong evidence in support of the validity of the model for use in direct model based controller design. The excellent agreement between the model and experimental data summarized above is attributed in large part to the use of effective lengths within the model, as functions of axial Mach number and nondimensional compressor rotational speed, as prescribed by the modeling technique. The use of these effective lengths proved to be far superior to the use of physical lengths. The use of these effective lengths also provided substantial improvement over the use of physical lengths coupled with fixed first-order empirical lags, as proposed by other authors for the modeling of observed compressor dynamic lag. The overall success of this model is believed to represent a positive first step toward a complete experimental validation of the approach to control-oriented high-frequency turbomachinery modeling being developed by the authors