An Improved Axial Flow Compressor Design

In using the method of stage stacking to compute the off-design performance of multi-stage axial compressors, it has been observed that the limitation on performance at speeds above the design speed has been set by the stall and the choke points of the rear stages(1). Thus if the rear stages can absorb a wide range of mass flows between stalled conditions and choked conditions, a better performance could be obtained.Compressor stages using low stagger blades will absorb a large range of mass flow between stalled and choked condition; but because of the high axial velocity involved in their use, they tend to be unsuitable for low pressure stages because of the high Mach number obtained. In the higher pressure stages the increased gas temperature will lower the Mach number for the same velocity and give more efficient operation.

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The Measurement and Interpretation of Flow within Rotating Stall Cells in Axial Compressors

Journal of Mechanical Engineering Science ◽

10.1243/jmes_jour_1978_020_017_02 ◽

1978 ◽

Vol 20 (2) ◽

pp. 101-114 ◽

Cited By ~ 58

Author(s):

I. J. Day ◽

N.A. Cumpsty

Keyword(s):

Flow Direction ◽

Axial Flow ◽

Tangential Direction ◽

Rotating Stall ◽

Design Flow ◽

Flow Measurements ◽

Axial Compressors ◽

Multi Stage ◽

Wide Range ◽

Flow Compressor

Detailed flow measurements obtained by a new measuring technique are presented for the flow in a stalled axial-flow compressor. Results were obtained from a wide range of compressor builds, including multi-stage and single-stage configurations of various design flow rates and degrees of reaction. Instantaneous recordings of absolute velocity, flow direction and total and static pressures have been included for both full-span and part-span stall. With the aid of these results, it has been shown that the conventional model of the flow in a stall cell is erroneous. An alternative model is proposed, based on the observation that the fluid must cross from one side of the cell to the other in order to preserve continuity in the tangential direction. An investigation of the experimental results also reveals the finer details of the flow in the cell and shows how these details are related to the design flow rate of the compressor. The influence of these cell details on the power absorbed by a stalled compressor are investigated, and consideration is given to the complex pressure patterns encountered in the compressor.

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Stability of Multi-Stage Axial Flow Compressors

Aeronautical Quarterly ◽

10.1017/s0001925900003164 ◽

1964 ◽

Vol 15 (4) ◽

pp. 328-356 ◽

Cited By ~ 2

Author(s):

W. T. Howell

Keyword(s):

Axial Flow ◽

Rotational Frequency ◽

Oscillatory Instability ◽

Operating Point ◽

Axial Flow Compressor ◽

Multi Stage ◽

Wide Range ◽

Surge Line ◽

Flow Compressor ◽

The Stability

SummaryThe following theoretical investigation is concerned with the stability of the flow through a system composed of a multi-stage axial flow compressor followed by a throttle.Such an investigation was carried out by Pearson and Bowmer in 1949. In 1962 Pearson’s work on the analysis of axial flow compressor characteristics, and the accumulation of empirical data regarding factors affecting the surge line, re-awakened interest in the possibility of predicting the surge line of a multi-stage axial flow compressor-throttle system.In this paper the equations governing the stability of flow at any operating point in such a system are obtained by applying Kirchhoff’s laws to the associated electric circuit at that operating point, and the analysis is applied to a wide range of flows of the calculated characteristics of a seven-stage axial flow compressor.A study of the simplest compressor-throttle system is given, in which the equations of motion of the system are derived mechanically and electrically, and the range of validity of the equations and their stability are discussed in order to bring out the relation between the mathematics and physics of the simple system before applying these methods to multi-stage axial flow compressors.For the relatively simple electrical representation used in this paper for an axial compressor of n stages, there are shown to be 2n possible values of p, the transient rotational frequency, and these are determined over a sufficiently wide range of flows on the seven-stage compressor studied.As a result, a region of the compressor characteristic map can be marked out in which all the values of the transient rotational frequency have their real parts less than zero, corresponding to stability of operation, a region where at least one of the values of p is real and positive corresponding to non-oscillatory instability of operation, and an intermediate region where some of the values of the rotational frequency p are complex with positive real part, corresponding to oscillatory instability of operation.It is suggested that the non-oscillatory instability found here is associated with the surge and the line of inception of non-oscillatory instability with the surge line.

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A Wide-Range Axial-Flow Compressor Stage Performance Model

Volume 1: Turbomachinery ◽

10.1115/92-gt-058 ◽

1992 ◽

Cited By ~ 2

Author(s):

Gregory S. Bloch ◽

Walter F. O’Brien

Keyword(s):

Axial Flow ◽

Operating Conditions ◽

System Response ◽

Compressor Stage ◽

Operating Characteristics ◽

Compression System ◽

Axial Flow Compressor ◽

Multi Stage ◽

Wide Range ◽

Flow Compressor

Dynamic compression system response is a major concern in the operability of aircraft gas turbine engines. Multi-stage compression system computer models have been developed to predict compressor response to changing operating conditions. These models require a knowledge of the wide-range, steady-state operating characteristics as inputs, which has limited their use as predicting tools. The full range of dynamic axial-flow compressor operation spans forward and reversed flow conditions. A model for predicting the wide flow range characteristics of axial-flow compressor stages was developed and applied to a 3-stage, low-speed compressor with very favorable results and to a 10-stage, high-speed compressor with mixed results. Conclusions were made regarding the inception of stall and the effects associated with operating a stage in a multistage environment. It was also concluded that there are operating points of an isolated compressor stage that are not attainable when that stage is operated in a multi-stage environment.

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A Numerical Investigation of Loss Coefficient Variation in Various Incidence Angles in Tandem Blades Cascade

Volume 1: Advances in Aerospace Technology ◽

10.1115/imece2014-39881 ◽

2014 ◽

Author(s):

Arash Soltani Dehkharqani ◽

Masoud Boroomand ◽

Hamzeh Eshraghi

Keyword(s):

Pressure Ratio ◽

Axial Flow ◽

Suction Side ◽

Loss Coefficient ◽

Flow Coefficient ◽

Flow Angle ◽

Multi Stage ◽

Wide Range ◽

And Performance ◽

Flow Compressor

There is a severe tendency to reduce weight and increase power of gas turbine. Such a requirement is fulfilled by higher pressure ratio of compressor stages. Employing tandem blades in multi-stage axial flow compressors is a promising methodology to control separation on suction sides of blades and simultaneously implement higher turning angle to achieve higher pressure ratio. The present study takes into account the high flow deflection capabilities of the tandem blades consisting of NACA-65 airfoil with fixed percent pitch and axial overlap at various flow incidence angles. In this regard, a two-dimensional cascade model of tandem blades is constructed in a numerical environment. The inlet flow angle is varied in a wide range and overall loss coefficient and deviation angles are computed. Moreover, the flow phenomena between the blades and performance of both forward and afterward blades are investigated. At the end, the aerodynamic flow coefficient of tandem blades are also computed with equivalent single blades to evaluate the performance of such blades in both design and off-design domain of operations. The results show that tandem blades are quite capable of providing higher deflection with lower loss in a wide range of operation and the base profile can be successfully used in design of axial flow compressor. In comparison to equivalent single blades, tandem blades have less dissipation because the momentum exerted on suction side of tandem blades confines the size of separation zone near trailing edges of blades.

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Monitoring of Aerodynamic Load and Detection of Stall in Multi Stage Axial Compressors

Volume 1: Aircraft Engine; Marine; Turbomachinery; Microturbines and Small Turbomachinery ◽

10.1115/93-gt-020 ◽

1993 ◽

Cited By ~ 1

Author(s):

H. Hönen ◽

H. E. Gallus

Keyword(s):

Axial Flow ◽

Operating Conditions ◽

Normal Operation ◽

Aerodynamic Load ◽

Frequency Spectra ◽

Axial Compressors ◽

Multi Stage ◽

Flow Compressor ◽

The Stability ◽

Hot Film

The unsteady flow in a single stage axial flow compressor at different operating conditions has been investigated with hot wire and hot film probes to find out the influence of the aerodynamic compressor load onto the periodic fluctuations. These results are compared with measurements in the last stages of a multi stage high pressure compressor of a gas turbine for normal operation and under stall conditions. From the patterns of the frequency spectra of the measuring signals a parameter for the detection of the approach to the stability line of a compressor is derived. A method for the on line monitoring of the aerodynamic load is presented. Based on these results a monitoring system has been developed. First experiences with this system, applied to two multi stage compressors are reported.

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Predictions of the Flow in Repeating Stages of Axial Compressors Using Navier-Stokes Solvers

Volume 1: Turbomachinery ◽

10.1115/95-gt-199 ◽

1995 ◽

Cited By ~ 2

Author(s):

John J. Bolger ◽

John H. Horlock

Keyword(s):

Flow Analysis ◽

Axial Flow ◽

Navier Stokes ◽

Good Prediction ◽

Viscous Effects ◽

Flow Angle ◽

Axial Compressors ◽

Multi Stage ◽

Flow Compressor ◽

Comparison With Experimental Data

In a well designed multi-stage axial flow compressor the flow quickly settles down to a repeating condition in which the flow angle and axial velocity profiles do not deteriorate further; they are more or less unchanged between entry to and exit from a deeply embedded stage. In early work, the flow in such repeating stages was studied using inviscid secondary flow analysis, coupled with empirical data on clearance flows, and also by inviscid numerical calculation. Underturning near the annulus walls was generally predicted but this was not convincingly confirmed by comparison with experimental data for repeating stage flows; it was apparent that viscous effects were important and should be taken into account. Further investigation of the flow in repeating stages has therefore been undertaken using Navier-Stokes solvers for comparison with early experimental results and improved test data more recently available. It is established that, with care, quite a good prediction of repeating stage flows can be made using steady-flow 3D viscous methods, and more general conclusions of greater validity can be drawn about over- or underturning at the annulus walls than the universal underturning predicted in the earlier inviscid approaches for moderately loaded stages.

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Three-Dimensional Flows and Loss Reduction in Axial Compressors

Journal of Turbomachinery ◽

10.1115/1.3262113 ◽

1987 ◽

Vol 109 (3) ◽

pp. 354-361 ◽

Cited By ~ 41

Author(s):

Y. Dong ◽

S. J. Gallimore ◽

H. P. Hodson

Keyword(s):

Three Dimensional ◽

Axial Compressor ◽

Axial Flow ◽

Tracer Gas ◽

Suction Surface ◽

Axial Compressors ◽

Small Clearance ◽

Oil Flow ◽

Stator Blade ◽

Flow Compressor

Measurements have been performed in a low-speed high-reaction single-stage axial compressor. Data obtained within and downstream of the rotor, when correlated with the results of other investigations, provide a link between the existence of suction surface–hub corner separations, their associated loss mechanisms, and blade loading. Within the stator, it has been shown that introducing a small clearance between the stator blade and the stationary hub increases the efficiency of the stator compared to the case with no clearance. Oil flow visualizaton indicated that the leakage reduced the extensive suction surface–hub corner separation that would otherwise exist. A tracer gas experiment showed that the large radial shifts of the surface streamlines indicated by the oil flow technique were only present close to the blade. The investigation demonstrates the possible advantages of including hub clearance in axial flow compressor stator blade rows.

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Some Blade Designs for an Axial Flow Compressor Stage

Journal of the Royal Aeronautical Society ◽

10.1017/s0368393100098138 ◽

1954 ◽

Vol 58 (517) ◽

pp. 61-64

Author(s):

R. G. Taylor

Keyword(s):

Mach Number ◽

Axial Flow ◽

Compressor Stage ◽

Axial Flow Compressor ◽

Design Specifications ◽

Reaction Condition ◽

Forced Vortex ◽

Vortex Solutions ◽

Flow Compressor ◽

Constant Mach Number

Two design conditions for an axial flow compressor stage are proposed and examined. These are, the constant reaction condition (incorporating I “ radial equilibrium ”), and the condition that the Mach number at inlet to the rotor shall be invariant with radius. In addition, the combination of these two properties in one stage is considered. It is found, with further assumptions regarding the nature of the flow, that a forced vortex type of flow will satisfy both design specifications. The forced vortex solutions for the various cases are presented, and for constant Mach number at inlet to the rotor, more general solutions are given.

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Development of a 6 MW-Class High-Efficiency Gas Turbine M7A-01

Volume 4: Heat Transfer; Electric Power; Industrial and Cogeneration ◽

10.1115/94-gt-066 ◽

1994 ◽

Author(s):

T. Sugimoto ◽

K. Ikesawa ◽

S. Kajita ◽

W. Karasawa ◽

T. Kojima ◽

...

Keyword(s):

Gas Turbine ◽

Thermal Efficiency ◽

High Efficiency ◽

Axial Flow ◽

Inlet Temperature ◽

Gas Temperature ◽

Flow Compressor ◽

Exhaust Gas Temperature ◽

Cycle Efficiency

The M7A-01 gas turbine is a newly developed 6 MW class single-shaft machine. With its high simple-cycle efficiency and high exhaust gas temperature. it is particularly suited for use in electric power generation and co-generation applications. An advanced high efficiency axial-flow compressor, six can-type combustors, and a high inlet temperature turbine has been adopted. This results in a high thermal efficiency of 31.5% at the gas turbine output shaft and a high overall thermal efficiency of co-generation system. In addition, low NOx emissions from the combustors and a long service life permit long-term continuous operation under various environmental limitations. The results of the full load shop test, accelerated cyclic endurance test and extra severity tests verified that the performance, the mechanical characteristics and the emission have satisfied the initial design goals.

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