Axial compressor

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

Energy efficiency study on axial flow impellers

Abstract: Theoretical equations are developed to relate the flow velocities in a tank with impeller power consumption, flow circulation efficiency index N Q / P 0 1 / 3 and other parameters. A non-dimensional parameter η = V /(( P /( ρT 2 )) 1/3 ) has been used to characterise the velocity energy efficiency. Laser Doppler velocimetry measurement studies were carried out on the flow field produced by a few commercial axial flow hydrofoil impellers and pitch bladed turbines operating in water and in a non-Newtonian shear-thinning fluid. The data were used to characterise the velocity energy efficiency. The results suggest that hydrofoil impellers are all equally efficient when operating in water. Varying impeller geometrical parameters such as number of blades, pitch angle had marginal effects on the flow energy efficiency. It is suggested that this principle be utilised to achieve some desirable plant improvement results. When operating in viscous non-Newtonian fluids, increased velocities at a given power input can be achieved via optimising impeller geometrical parameters. This effect is more pronounced at smaller Reynolds numbers.

Numerical Simulation of Stall and Stall Control in Axial and Radial Compressors

Abstract: : The performance of gas turbine engines is limited by compressor stall, and further exacerbated by combat conditions. Stall control technologies developed at the Army Research Laboratory (ARL) Vehicle Technology Directorate (VTD) and NASA Glenn Research Center (GRC) have demonstrated the effectiveness of steady tip injection to increase the stable operating range of high-speed axial and centrifugal compressors. A major element lacking in the development of the stall control technology is a tundamental understanding of the fluid mechanic processes of stall inception, and how stall is mitigated by the stall control technology to achieve increased compressor stall range. Such understanding is essential for providing improved design guidance in implementing stall control technology in engines. As such, in parallel with the engine demonstrator tests we are generating time-accurate, full-annulus, three-dimensional Navier-Stokes code simulations of single-stage axial and centrifugal compressors for which detailed experimental data are available, both with and without stall control technology. This paper presents results of the TURBO simulations, which show predicted range extension with stall control technology compared to measurements, and characteristics of the compressor flow field with and without stall control technology.

Three-Dimensional Structure and Decay of Vortices Behind an Axial Flow Rotating Blade Row

Abstract: Detailed measurements were made of the three-dimensional turbulent flow field behind an axial-flow rotating blade row. The flow was surveyed at 15 radial locations and 70 circumferential sampling points in five measuring planes parallel to the trailing edge of the rotor. Statistically accurate mean velocities as well as turbulence stresses were obtained from numerous hot-wire signals, more than 12,000 for each sampling point. Vorticities were derived by the numerical differentiation of these data. The three-dimensional structure of various kinds of vortices generated through the rotor, such as a leakage vortex, trailing vortices, scraping vortices, a horseshoe vortex, etc. were elucidated quantitatively by use of the local streamwise, lateral and normal components of vorticity. The decay characteristics of these vortices were investigated in relation to the distribution of the turbulent stresses.

Active Control of an Axial Flow Compressor via Pulsed Air Injection

Abstract: This paper presents the use of pulsed air injection to control the onset of rotating stall in a low-speed, axial flow compressor. By measuring the unsteady pressures near the rotor face, a control algorithm determines the magnitude and phase of the first mode of rotating stall and controls the injection of air in the front of the rotor face. Experimental results show that this technique slightly extends the stall point of the compressor and eliminates the hysteresis loop normally associated with rotating stall. A parametric study is used to determine the optimal control parameters for suppression of stall. Analytic results---using a low-dimensional model developed by Moore and Greitzer combined with an unsteady shift in the compressor characteristic to model the injectors---give further insights into the operation of the controller. Based on this model, we show that the behavior of the experiment can be explained as a change in the bifurcation behavior of the system under nonlinear feedback. A higher fidelity simulation model is then used to further verify some of the specific performance characteristics that are observed in experiments.