Axial compressor

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

Rotating Stall Control in a High-Speed Stage With Inlet Distortion: Part II — Circumferential Distortion

Abstract: This paper presents the first attempt to stabilize rotating stall in a single-stage transonic axial flow compressor with inlet distortion using active feedback control. The experiments were conducted at the NASA Lewis Research Center on a single-stage transonic core compressor inlet stage. An array of 12 jet injectors located upstream of the compressor was used for forced response testing and feedback stabilization. Results for a circumferential total pressure distortion of about one dynamic head and a 120 deg extent (DC(60) = 0.61) are reported in this paper. Part I (Spakovszky et al., 1999) reports results for radial distortion. Control laws were designed using empirical transfer function estimates determined from forced response results. Distortion introduces coupling between the harmonics of circumferential pressure perturbations, requiring multivariable identification and control design techniques. The compressor response displayed a strong first spatial harmonic, dominated by the well-known incompressible Moore-Greitzer mode. Steady axisymmetric injection of 4 percent of the compressor mass flow resulted in a 6.2 percent reduction of stalling mass flow. Constant gain feedback, using unsteady asymmetric injection, yielded a further range extension of 9 percent. A more sophisticated robust H controller allowed a reduction in stalling mass flow of 10.2 percent relative to steady injection, yielding a total reduction in stalling mass flow of 16.4 percent.

Unsteady Flow in a Rigid 3-D Model of the Carotid Artery Bifurcation

Abstract: In the present study, finite element calculations are performed of blood flow in the carotid artery bifurcation under physiological flow conditions. The numerical results are compared in detail with laser-Doppler velocity measurements carried out in a perspex model. It may be concluded that the numerical model as presented here is well capable in predicting axial and secondary flow of incompressible Newtonian fluids in rigid-walled three-dimensional geometries. With regard to the flow phenomena occurring, a large region with reversed axial flow is found in the carotid sinus opposite to the flow divider. This region starts to grow at peak systole, has its maximal shape at minimal flow rate and totally disappears at the start of the acceleration phase. C-shaped axial velocity contours are formed in the deceleration phase, which are highly influenced by secondary flows. These latter flows are mainly induced by centrifugal forces, flow branching, and tapering of the carotid sinus. Lowering the sinus angle, the angle between the main branch and the carotid sinus, results in a smaller region with reversed axial flow.

Axial flow fan having counter-rotating dual impeller blade arrangement

Abstract: A counter-rotating axial flow fan for cooling electronic components comprising two or more impellers with narrow chord blades. At least one impeller rotates in a first direction and at least one impeller rotates in a second direction opposite to the first direction. The blades of the impellers are configured so as to cause air to flow in the same axial direction. The air flow generated by this counter-rotating fan is substantially greater than the air flow of an otherwise identical co-rotating fan.

Variable fan inlet guide vane assembly, turbine engine with such an assembly and corresponding controlling method

Abstract: A turbine engine includes a plurality of variable fan inlet guide vanes. Where the turbine engine is a tip turbine engine, the variable fan inlet guide vanes permit the ability to control engine stability even though the fan-turbine rotor assembly is directly coupled to the axial compressor at a fixed rate. The fan inlet guide vanes may be actuated from an inner diameter of the fan inlet guide vanes.