Axial compressor

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

Theoretical study of a novel refrigeration compressor – Part II: Performance of a rotating discharge valve in the revolving vane (RV) compressor

Abstract: A new refrigeration compressor, named ‘Revolving Vane (RV) compressor’, has been introduced in Part I of this paper series For a first time in refrigeration compressors, a rotating discharge valve is employed in the RV compressor mainly due to the rotation of the entire cylinder This paper presents a theoretical investigation on the dynamic behavior of a reed-type discharge valve undergoing rotatory motion, with the primary objective of elucidating the applicability of such valves in refrigeration compressors Under the application of the Euler–Bernoulli beam theory, a mathematical model of the rotating valve is formulated and the transient response of the valve under centrifugal loads in addition to pressure forces is analyzed Results have shown that under careful design considerations, the performance as well as the reliability of the rotating discharge valve can be enhanced as compared to a non-rotating valve that has been used in all refrigeration compressors currently

Unsteady Aerodynamics, Aeroacoustics and Aeroelasticity of Turbomachines

Abstract: Foreword. Preface. Part 1: Flutter-Flutter boundaries for pairs of low pressure turbine blades-Influence of a vibration amplitude-A method to assess flutter stability of complex modes-Flutter design of low pressure turbine blades with cyclic symmetric modes-Experimental and numerical investigation of 2D palisade flutter for the harmonic oscillations-Possibility of active cascade flutter control with smart structure in transonic flow condition-Experimental flutter investigations of an annular compressor cascade: influence of reduced frequency on stability.- Part 2: Forced responses-Unsteady gust response in the frequency domain-Axial turbine blade vibrations induced by the stator flow-Mistuning and coupling effects in turbomachinery bladings-Evalution of the principle of aerodynamic superposition in forced response calculations-Comparison of models to predict low engine order excitation in a high pressure turbine stage-Experimental reduction of transonic fan forced response by IGV flow control.- Part 3: Multistage effects-Unsteady aerodynamic work on oscillating annular cascades in counter rotation-Stucture of unsteady vortical wakes behind blades of mutual-moving rows of an axial turbomachine-The effect of mach number on LP turbine wake-blade interaction-Multistage coupling for unsteady flows in turbomachinery- Part 4: Aeroacoustics- Passive noise control by vane lean and sweep-Interaction of acoustic and vortical disturbances with an annular cascade in a swirling flow-Influence of mutual circumferential shift of stators on the noice generated by systems of rows stator-rotor-stator of the axial compressor-A frequency-domain solver for the non-linear propagation and radiation of fan noise- Part 5: Flow instabilities-Analysis of unsteady casing-Core compressor rotating stall simulation with a multi-bladerow model-Parametric study of surface roughness and wake unsteadiness on a flat plate with large pressure gradient-Bypass flow pattern changes at turbo-ram transient operation of combined cycle engine-Experimental investigation of wake-induced transition in a highly loaded linear compressor cascade-Experimental off-design investigation of unsteady secondary flow phenomena in a three-stage axial compressor at 100% nomial speed-Analyses of URANS and LES- Part 6: Computational techniques-Frequency and time domain-Study of shock movement and unsteady pressure on 2D generic model-Numerical unsteady aerodynamics for turbomachinery aeroelasticity-Development of an efficient and robust linearised navier-stokes flow solver-Optimized dual-time stepping technique for time-accurate navier-stokes calculations- Part 7: Experimental unsteady aerodynamics-Experimental and numerical study of nonlinear interactions in two-dimensional transonic nozzle flow-Interaction between shock waves and cascaded blades-Measured and calculated unsteady pressure field in a vaneless diffuser of a centrifugal compressor-DPIV measurements of the flow field between a transonic rotor and an upstream stator-Unsteady pressure management with correction on tubing distortion- Part 8: Aerothermodynamics-Unsteady 3D navier-stokes-Analysis of unsteady aerothermodynamic effects in a turbine-combustor- Part 9: Rotor stator interaction-Stator-rotor aeroelastic interaction for the turbine last stage in 3D transonic flow-Effects of stator clocking in systems of rows-Rotor-stator interaction in a highly loaded, single-stage, unsteady measurments in the rotor relative frame-Two-stage turbine experimental investigations of unsteady stator-to-stator interaction.

Stability Improvement of High-Pressure-Ratio Turbocharger Centrifugal Compressor by Asymmetric Flow Control-Part I: Non-Axisymmetrical Flow in Centrifugal Compressor.

Abstract: The history of turbocharging is almost as old as that of the internal combustion engine. A turbocharger consists of a compressor and a turbine. The compressor is driven by the turbine extracting energy from exhaust gases. Compared to a naturally aspirated engine, the benefits of a turbocharged engine are increased power, lower fuel consumption, and reduced emissions [1,2]. High-pressure-ratio turbocharging technology is the developing trend of turbocharged internal combustion engines due to the following reasons: 1) significant downsizing to mitigate CO2 emission and reduce fuel consumption [3], 2) satisfying rigid future emission regulations, i.e., NOx treatment by engine control means high rates of exhaust gas recirculation (EGR) [3,4], and 3) the facilitation of high altitude operation [5]. However, a high pressure ratio causes the flow in the compressor to be transonic. Hence, the stable flow range is narrowed, since the stall incidence decreases with an increased relative Mach number at the inlet of the impeller [6]. Therefore, map width enhancement is a major issue for state-of-the-art high-pressure-ratio compressor design and development. A turbocharger centrifugal compressor comprises an impeller, a diffuser, and a volute. While the former two are periodically symmetric in the circumferential direction, the volute is asymmetric due to its gas-collection function. It is usually designed as a spiral-collection overhung housing that collects the air from the diffuser and passes it to the pipe system. It has been recognized that the improvement of centrifugal compressor performance requires a good understanding of the flow mechanisms inside the volute [7–9]; especially the interaction among the volute-diffuser-impeller [10,11]. The volute is mostly designed in a way to shape a uniform circumferential static pressure distribution both in the volute and the diffuser. However, the volute acts as a diffuser at lower than the design flow rate and acts as a nozzle at higher than the design flow rate, respectively. A number of authors have researched this subject. It has already been confirmed that the asymmetrical configuration has a significant impact on the flow field in the diffuser and in the impeller [12,13]. This circumferential asymmetry has been recognized and intensive experimental investigations of the flow within the volute and the propagation of the distortion into upstream components were carried out for subsonic compressor units [14,15]. The work of Sorokes et al. confirmed that the pressure nonuniformity extended upstream of the impeller, implying that the impeller was subjected to varying inlet and exit conditions. The computational fluid dynamics (CFD) results further implied that the inlet flow distortion caused a large leading edge pressure differential along with a large negative incidence, which may induce a flow separation and thus a very disturbed flow field in the impeller [14]. A three-dimensional unsteady analysis of the flow in the impeller with circumferential distortion of the outlet static pressure was investigated using a numerical method by Fatsis et al. [16]. The perturbation was thus propagated upstream from the impeller outlet and influenced the incidence at the blade leading edges and other flow parameters. Gu et al. [10,11] found that the performance parameters of the single impeller passage differed because of the asymmetric flow at the outlet of the impeller. There was almost no phase shift between the distortion in the diffuser and impeller according to their results, and it was considered that the unsteady effects of the volute-impeller interaction can be neglected when the Strouhal number is small enough. Little detailed measurement was carried out in the impeller to investigate the asymmetric flow. Furthermore, to the authors’ knowledge, very little research work has been focused on the impact of the volute on the flow field in a high-pressure-ratio turbocharger centrifugal compressor. The purpose of this two-part paper is first to understand the asymmetry of flow field due to the asymmetric geometry of the volute and, subsequently, to develop a novel asymmetric flow control method to widen the stable flow range of a turbocharger centrifugal compressor with a high-pressure-ratio, the narrowing flow range of which is of utmost importance for its application. In Part I, the nonaxisymmetrical flow characteristics in the high-pressure-ratio turbocharger centrifugal compressor are investigated by using experimental and numerical means, the results of which are the basis for the work presented in Part II.

Numerical simulation of compressor endwall and casing treatment flow phenomena

Abstract: A numerical study is presented of the flow in the endwall region of a compressor blade row, in conditions of operation with both smooth and grooved endwalls. The computations are first compared to velocity field measurements in a cantilevered stator/rotating hub configuration to confirm that the salient features are captured. Computations are then interrogated to examine the tip leakage flow structure since this is a dominant feature of the endwall region. In particular, the high blockage that can exist near the endwalls at the rear of a compressor blade passage appears to be directly linked to low total pressure fluid associated with the leakage flow. The fluid dynamic action of the grooved endwall, representative of the casing treatments that have been most successful in suppressing stall, is then simulated computationally and two principal effects are identified. One is suction of the low total pressure, high blockage fluid at the rear of the passage. The second is energizing of the tip leakage flow, most notably in the core of the leakage vortex, thereby suppressing the blockage at its source.