Axial compressor

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

Thermal effects in compressible viscous flow in a capillary

Abstract: The thermal effects for a compressible viscous flow in a capillary have been calculated by solving the equation of energy, where a parabolic profile is assumed for the axial flow velocity. It is shown that, in general, the temperature changes are small (a few millikelvins), consistent with the current assumption of an isothermal flow, except in the case of a critical, i.e., very compressible, fluid where the cooling can be substantial. This effect is demonstrated numerically on the basis of a flow of ethylene in nearly critical circumstances.

The Tip Clearance Flow Resonance Behind Axial Compressor Nonsynchronous Vibration

Abstract: Nonsynchronous vibration (NSV) is a particular type of aero-elastic phenomenon, where the rotor blades vibrate at nonintegral multiples of the shaft rotational frequencies. NSV behavior appears similar to off-design stall flutter but with a particular blade tip flow evolution. This paper demonstrates the link between NSV and the resonance induced by the tip clearance flow based on a proposed hypothesis and experimental confirmation. At off-design operating conditions, the rotor blade tip clearance shear layer flow can evolve tangentially. It is proposed that this tangential flow becomes a support for an acoustic feedback wave that settles between rotor blades. The feedback wave is driven by the blade vibratory motion and synchronizes the shear layer vortical structures with the blade vibration frequency. Depending on the blade tip local temperature, and when the feedback wavelength matches within one or two blade pitches, the system becomes resonant and very high vibrations can occur on the blade. An axial stage compressor test rig is set-up to look into the underlying mechanism behind NSV through targeted measurements using both static and rotating instrumentation. The experimental apparatus consists of the first stage of a high pressure compressor driven by an electric motor. The test-section is built to minimize the effects of the adjacent stator blade rows in order to isolate the role of rotor blade tip clearance flow on NSV. Sensitivity studies are carried out to assess and demonstrate the effects of the rotor blade tip clearance and inlet temperature on NSV and validate the predicted resonance for NSV occurrence under various conditions. Vibrations and surface pressure data from adjacent blades are collected to demonstrate the predicted interactions between neighboring rotor blades. Finally, evidence of the staging phenomenon, inherent to the proposed NSV mechanism, is experimentally obtained. All the data obtained are consistent with and thus in support of the proposed mechanism for NSV.

Three-Dimensional-Flow Theories for Axial Compressors and Turbines

Abstract: It has long been known that the energy losses occurring in an axial compressor or turbine cannot be fully accounted for by the skin-friction losses on the blades and annulus walls. The difference, usually termed secondary loss, is attributed to miscellaneous secondary flows which take place in the blade row. These flows both cause losses in themselves and modify the operating conditions of the individual blade sections, to the detriment of the overall performance. This lecture analyses the three-dimensional flow in axial compressors and turbines, so that, by appreciation of the factors involved, possible methods of improving the performance can readily be investigated.The origin of secondary flow is first examined for the simple case of a straight cascade. The physical nature of the flow, and theories which enable quantitative estimates to be made, are discussed at some length. Following this, the three-dimensional flow in an annulus with a stationary blade row is examined, and, among other things, the in...

Modeling of Turbine Engine Axial-Flow Compressor and Turbine Characteristics

Abstract: This paper describes the concept of modeling the turbine engine axial-e ow compressor and turbine characteristics. The conception is based on the use of two variables to the approximation of these characteristics’ curves. It gives the possibility of modeling the whole area of their action and provides the utmost accuracy of their representation. The conception is original because it presents changes of a compressor and turbine’ s parameters of work in the unconventional coordinate system, as suggested by the authors. The accuracy of the conception of modeling has been tested on the exemplary characteristics of a compressor and turbine in a turbine engine. Research is carried out in the following spheres: 1 ) evaluation of the degradation of engine components’ ine uence on the turbomachinery working line, and 2 ) evaluation of the inefe ciency of the fuel supply system’ s ine uence on the change of the thermodynamic cycle’ s parameters in the stationary and transient states. This research will also include a nonlinear digital model of a turbine engine, and the conception of modeling characteristics of rotating components, and the mass accumulation in the subassemblies of the engine.

Axial laminar flow of viscoplastic fluids in a concentric annulus subject to wall slip

Abstract: The flow of non-Newtonian fluids in annular geometries is an important problem, especially for the extrusion of polymeric melts and suspensions and for oil and gas exploration. Here, an analytical solution of the equation of motion for the axial flow of an incompressible viscoplastic fluid (represented by the Hershel–Bulkley equation) in a long concentric annulus under isothermal, fully developed, and creeping conditions and subject to true or apparent wall slip is provided. The simplifications of the analytical model for Hershel–Bulkley fluid subject to wall slip also provide the analytical solutions for the axial annular flows of Bingham plastic, power-law, and Newtonian fluids with and without wall slip at one or both surfaces of the annulus.