This paper investigates hub and shroud endwall boundary layers, and the corresponding blockages of a fivestage axial compressor under different conditions. Table 1 input parameters for detailed specifications detailed specifications rotor stator aspect ratio ar 2. Numerical studies on the effect of slotted casing treatment. Numerical simulations of unsteady flow instabilities rotating stall in pumps by. Effect of blade sweep on inlet flow in axial compressor. Finally, the implications and conclusions of the research are summarized. In axial flow compressors, the gap between the casinghub and rotorstator blade tip results in leakage flow, which is well known to have a strong impact on its overall performance and stability, as measured in terms of efficiency, pressure rise capability, and stall margin.
The performance is characterized by the pressure ratio across the compressor cpr, the rotational speed of the shaft necessary to produce the pressure increase, and an efficiency factor that indicates. Stage pressure ratios can be increased for the same loading limit, that is p tpji or dfactor, by increasing the design. A casing treatment with axial grooves for centrifugal. Table 1 design parameters of the test compressor parameter value. Method of calculation of slip factor in centrifugal. The rotating blades impart kinetic energy to the air while increasing. Stage pressure ratios can be increased for the same loading limit, that is p tpji or d factor, by increasing the design. The purpose of this work is to provide a method for the design of an axial flow compressor stage. A multistage axial compressor as its name indicates, it consists of several stages. Aerodynamic investigation and optimization of a 5stage. Detailed laser anemometer measurements were acquired upstream, within, and downstream of a transonic, axial compressor rotor operating at 100, 85, 80, and 60 percent of design speed, which provided inlet relative mach numbers at the blade tip of 1.
Parametric study on axial compressor performance in design condition sarallah abbasi a, ali joodaki b a. The term blockage is used with reference to the entire structure. Parametric study on axial compressor performance in design. Many factors were considered in choosing the compressor. Axial compressor design parameters turbine materials. Recent advances in transonic axial compressor aerodynamics. The instability is characterized by large limit cycle oscillations in compressor. The estimate of cumpsty 1989 of the boundary layer growth is used in the local codes. The math model empirical coefficient xi takes into account a boundary layer blockage factor. Pdf the effect of upstream duct boundary layer growth. Axial compressor design parameters free download as powerpoint presentation.
In these studies, the effects of aspect ratio, mu sion factor, and solidity on rotor and stage performance are being determined. Design and optimization of a multistage axialflow compressor. The compressor stage provided a strongly increased stall margin 56. It is of engineering interest to have means of predicting axial compressor instability and to have design methodologies that can delay the onset of axial. A computer program for the coupled implementation of. End wall flow characteristics and overall performance of. A modified stagestacking method for multistage axial flow compressor calculations tonye k. Two dimensional design of axial compressor lund university. A tandem stator design is employed in this compressor because of the high diffusion factor in the rotor hub region. Two dimensional design of axial compressor main characteristics page 6 axial compressor can elaborate a higher flow than the radial, which has a higher pressure ratio per stage, this means that for the same flow rate the firsts will have a smaller diameter, but it will need more stages to reaches the same pressure ratio. The ct design is an adaptation from an axial highpressure compressor, which was successfully. Compressor design velocitydiagram calculations in the design of this transonic axial flow compressor rotor, no attempt was made to maximize the values of totalpressure ratio or corrected specific weight flow, since this test program was initiated to determine the bladeelement performance for a compressor operating in a range currently of. Results are reported from a linear compressor cascade.
Impact of channel blockage on the performance of axial and. Effects of air injection on aerodynamic performance of a. The performance of axial flow compressors is known to be adversely affected by increasing the aspect ratio the ratio of blade height to chord length. Effect of blade sweep on inlet flow in axial compressor cascades. The tip leakage flow over the blades of an axial compressor rotor adversely affects the axial rotor efficiency and can determine the onset of tip leakage stall. The design of an axial compressor stage for a total. Numerical simulations, measurements in a lowspeed compressor, and measurements in a wind tunnel designed to simulate a compressor clearance flow are used to assess the approach. Figure3 illustrates the two stage axial compressor in isometric view. Applications of numerical simulation method to multistage. The blockage factor is applied to the undisturbed current i. The results show that the hub displacement thickness increases from the front to rear stage, whereas the shroud.
Two different axial positions of the slots were studied. Design and analysis of stator, rotor and blades of axial flow compressor issn. The results showed that the total pressure ratio, stall margin and stability increased when the circumferential coverage percentage. This latter represents the front stage of a multistage compressor of industrial gas turbine. Likewise, this paper presents a comparative numerical study of cascades to investigate the effect of blade sweep on inlet.
In the prior research, experimental and numerical methods. This paper provides an investigation of a casing treatment ct approach for pressure ratio improvements of centrifugal compressors between peak efficiency and surge. Compressor and turbine stages university of cambridge. Elder abstract in this paper an attempt was made at studying multisage axial flow compressor offdesign performance based on two existing. Buckling of axially loaded compression members the critical buckling load pcr for columns is theoretically given by equation 3. An axial compressor is a gas compressor that can continuously pressurize gases. The new performance calculation method of fouled axial flow. Stagestacking is used to analyse a multistage compressor. The calculating method of flow field diagnosis in multistage axial compressors is presented in this paper. Jul 26, 2017 design of axial flow compressors proper integration of mild compression stages p m v subbarao professor mechanical engineering department design specifications a the different input parameters, used in design process are. A result of this is that the blockage factor should be the same for the rotorinlet and the statoroutlet at the previous stage. Influence of rotor tip blockage on near stall blade. Effect of casing aspiration on the tip leakage flow in the.
It is found that by application of a recirculating tip injection ti casing treatment, the aeroelastic stability increases as a result of reduced blockage in the rotor tip region. Manual for axial flow compressor conceptual design code cspan arthur j. Axial compressor design parameters turbine materials science. The analysis thus developed allows predictions of endwall blockage associated with variations in tip clearance, blade stagger angle, inlet boundary layer thickness. Endwall boundary layers and induced blockages are important factors for multistage axial compressors performance. Fouling is the most important performance degradation factor, so it is necessary to accurately predict the effect of fouling on engine performance. A simple method of flow field diagnosis in multistage axial. The geometry is the same for the rotor inlet as for the statoroutlet in the previous stage. Conclusion this study demonstrated the design of a two firststage.
Pdf core compressor aerodynamic design david rowlands. Main specification detailed specification inlet specification specifications of axial flow compressor a main specification a type of compressor a mass. This vortex creates a blockage, thereby decreasing the effective flow area of the throughflow a primary factor in determining the pressure rise capability of the machine. The test compressor is a transonic compressor stage which is actually used in an aeroengine, and the design parameters are shown in table 1. The current blockage factor introduced to account for the presence of the structure in the current flow field enables one to compute the true global load on the structure. This work deals with the numerical simulation of axial flow compressors, from design to performance prediction. May 05, 2015 compressor designers must rely on wind tunnel testing and sophisticated computational models to determine the performance of an axial compressor. This paper develops a new performance calculation method of fouled multistage axial flow compressor based on experiment result and operating data.
Experimental investigation of the flow mechanisms and the. Axial compressor instabilities can occur as stall and surge hill and peterson, 1. A detailed experimental investigation to understand and quantify. Pressure ratio at a certain mass flow setting, is eventually reduced due to the high er axial velocities caused by the reduced.
A modified stagestacking method for multistage axial. So, the whole compressor is divided into two parts in this model. Axial compressor instability is a major limiting factor in the design and use of gas turbine engines. Coordinate system for axialflow compressor figure 5 shows the pressure, velocity, and total temperature variation for. Numerical simulations of unsteady flow instabilities. A simple method of flow field diagnosis in multistage. The naca 5stage transonic compressor overall performance shows good agreement at all speeds, except for 90% of design speed. The design of two singlestage axialflow compressors for a stage. Experimental investigations have been carried out on a singlestage, low speed axial flow compressor with a parallel annulus and a hubtip ratio of 0. The stage performance prediction uses the meanline flow properties. The flow instability rotating stall is simulated for a onestage water model of an axial compressor with 30 runner and 30 stator blades. Recently, the influence of circumferential grooves on the tip flow field of an axial singlestage transonic compressor has been examined both experimentally and numerically.
Compressor design velocitydiagram calculations in the design of this transonic axialflowcompressor rotor, no attempt was made to maximize the values of totalpressure ratio or corrected specific weight flow, since this test program was initiated to determine the bladeelement performance for a compressor operating in a range currently of. Licensed under creative commons attribution cc by applications of numerical simulation method to multistage axial flow compressor threedimensional flow field xuezeng zhao1, xigui wang 2, yongmei wang3 1mechatronics school, harbin institute of technology, harbin 150001, china. As the mass flow is decreased the pressure rise coefficient increases to a peak and then. The new performance calculation method of fouled axial. This differs from other rotating compressors such as centrifugal compressor, axicentrifugal compressors and mixedflow compressors where the fluid flow will include a radial. Summary the effects of diffusion factor, aspect ratio, and solidity on rotor and stage per formance have been evaluated for 14 subsonic compressor middle stages with a hubtip ratio of 0. Design and analysis of stator, rotor and blades of the. Axial compressors are characterised by lower pressure ratio per stage at. Work done factor is the ratio of the actual work absorbing. Enhanced capabilities and modified users manual for axial.
As the incidence angles increase in the compressor a point is reached when the flow begins to separate from the blades, with serious consequences. It is a rotating, airfoilbased compressor in which the gas or working fluid principally flows parallel to the axis of rotation, or axially. The proposed 2d design approach is based on the mean line concept which assumes that mean radius flow conditions prevailing at all other radial stations. In the previous research, it is very difficult to accurately model the fouled axial flow compressor. The distributions of loss and deviation angle of every blade row, and blockage factors are evaluated using tested total temperature and total pressure at inlet and outlet of compressor, as well as the endwall static pressures.
The blockage factor for steady current past a dense structure consisting of many circular members e. Passive flow control of the corner separation in an. In the jet engine application, the compressor faces a wide variety of operating conditions. Axial compressor centrifugal compressor t a k k u c 2 2 2 v 1 2 g tan e 0. In multiple stage axial flow compressor, fouling is more serious in the first 50% stages than rear stages where particles deposited are less.
Effect of a recirculating type casing treatment on a. Gode institute of fluid mechanics and hydraulic machinery, university of stuttgart abstract. The naca 10stage subsonic compressor shows good agreement for low and medium speeds, but needs improvement at 90% and 100% of design speeds. Blockage development in a transonic, axial compressor rotor. A computer program, written in fortran, was developed and is able to design an axial. Nasa technical memorandum 1115 blockage development in a transonic, axial compressor rotor kenneth l. Lowpressure axial compressor scheme of the olympus bol. On the ground at takeoff the inlet pressure is high, inlet speed zero, and the compressor spun at a variety of speeds as the power is applied.
Large incidence angles occur when the ratio axial velocityblade speed is low, i. The offdesign analysis of flow m axxl compressors 9. An overview of the literature reveals that few studies are carried out on the effect of the input parameters on the overall axial compressor performance in design condition. Nasa stage 37 and the threestage nasa 74a axial compressors were analyzed and. Instead, they propose to use correlations between the blockage ratio, power coefficient and the axial induction factor flow through the turbine from cfd simulations or measured piv data. The boundary layer may be simulated as a blockage factor in through.
Chen and liou 15 performed experimental measurements on a horizontalaxis wind turbine in a wind tunnel. Aerodynamically, only the blockage allowance attributed to annulus wall. This paper developed and validated a model which is able to evaluate the performance of fouled axial flow compressor. Results were experimentally verified for a variety of automotive turbocharger compressors and analyzed with 3d cfd. Suppose that there is a nonuniformity in the inlet flow such that a. A combination of kb blockage factor r radius m the all the pressure rise in each stage across the axial m mach number compressor eventually result in a. Flow blockage in a transonic axial flow compressor. A modified stagestacking method for multistage axial flow. Osman khan, phd, pe, consultant mechanical engineering dept. Consider a row of axial compressor blades operating at a high angle of attack, as shown in figure 1.
Dec 06, 2017 the investigations show that the blockage at the rotor tip is an important factor for the aeroelastic stability of the compressor in the ns region. Axial and centrifugal compressor mean line flow analysis method joseph p. Where a is the obstruction of the blade in the flow direction. A detailed experimental investigation to understand and quantify the development of blockage in the flow field of a transonic, axial flow compressor rotor nasa rotor 37 has been undertaken. For compressors there is no equivalent to the smith chart. Blade row and blockage modelling in an axial compressor. Aerodynamic investigation and optimization of a 5stage axial flow compressor yin song1, chunwei gu1, xiaotang li2. It was concluded that instead of a massive destruction of the tip leakage vortex tlv, it was more advantageous to manipulate the tip leakage flow in the. The design of a heavilyloaded, supersonic axial compressor stage is. Nasa technical memorandum 1115 blockage development in. Centrifugal compressor surge, modeling and identification. Veres national aeronautics and space administration glenn research center cleveland, ohio 445 abstract this paper describes a method to estimate key aerodynamic parameters of single and multistage axial and centrifugal compressors. The offdesign analysis of flow in axial compressors. Jan 25, 2014 this video show that how axial compressor working.
Endwall boundary layers and blockages of multistage axial. Three dimensional model of a two stage axial compressor has been generated based on the calculated data. A 2d aerodynamic design of subsonic axial compressor stage. Axial and centrifugal compressor mean line flow analysis method.
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