Compressor Variable Geometry Schedule Optimisation Using Genetic Algorithms

2009 ◽  
Author(s):  
L. Gallar ◽  
M. Arias ◽  
V. Pachidis ◽  
P. Pilidis
Keyword(s):  
High Efficiency ◽  
Engine Performance ◽  
Variable Geometry ◽  
Electric Generator ◽  
Axial Compressors ◽  
Turbine Efficiency ◽  
Surge Margin ◽  
Compressor Performance ◽  
Compressor Map ◽  
Generator Frequency

Variable geometry blade rows in axial compressors are devised to fulfil different requirements. Main objectives include their role as a “part speed crutch” to push the front stages out of surge at low spool speeds, modulation of the power output in industrial machines — given the fact that the spool needs to run at synchronous speed with the electric generator frequency — and they can also be re-staggered to attain a modified capacity (usually upflowed) of the same baseline compressor. The operating schedule of the variable vanes is typically obtained from expensive and time consuming performance rig tests in which a large number of possible combinations are compared. In principle, the final choice is dictated by the pursuit of high efficiency at high rotational speeds and increased surge margin at low speeds where large excursions away from the design point are expected. The aim of this work is to integrate a validated genetic algorithm optimiser within an industry proprietary mean line compressor performance prediction code to maximise the machine efficiency while keeping an adequate user-defined value of the surge margin. In so doing, an optimised variable geometry schedule is derived, together with a modified range of rotational speeds for each given operating point. Nevertheless, aware of the detrimental consequences to the whole engine performance that the new arrangement can cause, the whole engine response for the new settings has been investigated. In this regard and to a first order, the working line on the compressor map is considered unaffected by the setting of the variable vanes and the effect of the spool speed variation on the turbine operation is accounted for by a reduction in turbine efficiency proportional to any fall in the shaft speed. Results for a state of the art eight stage compressor show a marked improvement for the coupled compressor-turbine efficiency particularly at low spool speeds for a sensible value of the surge margin. Free from the surge margin constraint the efficiency is further increased at the expense of a hindered compressor operational stability. The work is intended to continue with the incorporation of bleeds and power off take in the calculations for the sake of a greater applicability of the tool.

Health Monitoring of Variable Geometry Gas Turbines for the Canadian Navy

1989 ◽  
Vol 111 (2) ◽  
pp. 244-250 ◽  
Author(s):  
D. E. Muir ◽  
H. I. H. Saravanamuttoo ◽  
D. J. Marshall
Keyword(s):  
Health Monitoring ◽  
Gas Turbines ◽  
Pressure Ratio ◽  
Engine Performance ◽  
Variable Geometry ◽  
Axial Compressors ◽  
High Pressure Ratio ◽  
Department Of National Defence ◽  
Canadian Navy ◽  
General Method

The Canadian Department of National Defence has identified a need for improved Engine Health Monitoring procedures for the new Canadian Patrol Frigate (CPF). The CPF propulsion system includes two General Electric LM2500 gas turbines, a high-pressure-ratio engine with multiple stages of compressor variable geometry. A general method for predicting the thermodynamic performance of variable geometry axial compressors has been developed. The new modeling technique is based on a meanline stage-stacking analysis and relies only on the limited performance data typically made available by engine manufacturers. The method has been applied to the LM2500-30 marine gas turbine and the variations in engine performance that can result from a malfunction of the variable geometry system in service have been estimated.

Resonant Intake and Variable Geometry Turbocharging Systems for a V8 Diesel Engine

1983 ◽  
Vol 197 (1) ◽  
pp. 27-36 ◽  
Author(s):  
N Watson
Keyword(s):  
Engine Performance ◽  
Maximum Speed ◽  
Pressure Curve ◽  
Boost Pressure ◽  
Variable Geometry ◽  
Maximum Torque ◽  
Variable Geometry Turbocharger ◽  
Turbine Efficiency ◽  
Mass Flowrate ◽  
Inlet Manifold

A mathematical model is used to analyse the performance of conventional and resonant (Cser type) intake systems on turbocharged six-cylinder and V8 engines. For the V8 the system is slightly less effective than for the six, but is more compact and easily installed within the V of the engine. An optimum system was designed and tested on a V8 engine, with maximum torque b.m.e.p. increasing from 12.0 bar at 1850 rev/min to 12.7 bar at a reduced speed of 1600 rev/min. Engine performance with the resonant system is compared to that with a simple variable-geometry turbocharger turbine, having only one major moving part. A mass-flowrate turndown of 42 per cent was achieved, but with a loss of turbine efficiency largely due to the constraints of adapting an existing turbocharger design. However a flat boost pressure curve was achieved from 1800–2600 rev/min. Maximum torque b.m.e.p. (with conventional inlet manifold) increased to 14 bar at 1600 rev/min. Engine performance at maximum speed (2600 rev/min) was unaffected with either system.

scholarly journals Development of Centrifugal Compressor for 100 kW Automotive Ceramic Gas Turbine

1994 ◽  
Author(s):  
Hiroshi Uchida ◽  
Mutsuo Shiraki ◽  
Akinobu Bessho ◽  
Yoichi Yagi
Keyword(s):  
Research And Development ◽  
Gas Turbine ◽  
Centrifugal Compressor ◽  
High Efficiency ◽  
Operating Conditions ◽  
Guide Vanes ◽  
Inlet Guide Vanes ◽  
Surge Margin ◽  
Partial Load ◽  
Compressor Performance

In Japan, a program of research and development of a 100 kW automotive ceramic gas turbine (CGT) has been carried out in the Petroleum Energy Center with active cooperation of petroleum, automobile and ceramics industries as well as other related industries. As a part of this research and development program, we have studied and developed a centrifugal compressor with variable inlet guide vanes for CGT engines. There has been a strong demand for a compressor with a high efficiency and a wide flow range. The compressor performance goals are an adiabatic efficiency of 81% and a surge margin of 8% under maximum power operating conditions. This paper describes the methods for designing impellers, diffusers and variable inlet guide vanes, and presents the results of compressor performance tests. The test results reveal that the surge margin and compressor efficiency at partial load are improved by using inlet guide vanes.

Experimental Investigation of the Diffuser Vane Clearance Effect in a Centrifugal Compressor Stage With Adjustable Diffuser Geometry: Part I — Compressor Performance Analysis

2014 ◽  
Author(s):  
Stefan Ubben ◽  
Reinhard Niehuis
Keyword(s):  
Centrifugal Compressor ◽  
High Efficiency ◽  
Negative Impact ◽  
Pressure Ratio ◽  
Industrial Applications ◽  
Flow Measurements ◽  
Flow Phenomena ◽  
Compressor Performance ◽  
Compressor Map ◽  
The Impact

The combination of variable speed control and adjustable diffuser vanes offers an attractive design option for centrifugal compressors applied in industrial applications where a wide operating range at high efficiency level and a favorable surge line is required. However, the knowledge about the impact on compressor performance of a diffuser vane clearance between vane and diffuser wall which is mandatory since the diffuser geometry adjustment has to take place during operation, is still not satisfying. This two-part paper summarizes results of investigations performed at the Institute of Jet Propulsion and Turbomachinery at RWTH Aachen with an industrial-like centrifugal compressor, featuring a design pressure ratio of 4 and a design speed of 35200 rpm. Particular attention was directed to the influence of the diffuser clearance on the operating behavior of the entire stage, the pressure recovery in the diffuser and on the diffuser flow by a systematic variation of the parameters diffuser clearance height, diffuser vane angle, radial gap between impeller exit and diffuser inlet, and rotor speed. Compressor map measurements provide a summary of the operating behavior related to diffuser geometry and impeller speed, whereas detailed flow measurements with temperature and pressure probes allow a breakdown of the losses between impeller and diffuser and contribute to a better understanding of relevant flow phenomena. The results presented in Part I show that an one-sided diffuser clearance does not necessarily has a negative impact on the operation and loss behavior of the centrifugal compressor, but instead may contribute to an increased pressure ratio and improved efficiency. The flow phenomena responsible for this detected performance behavior are exposed in Part II [28], where the results of detailed measurements with pressure probes at diffuser exit and Particle Image Velocimetry (PIV) measurements conducted inside the diffuser channel, revealing the complex and unsteady flow leaving the impeller and passing the diffuser channel, are discussed. The experimental results are published as an open CFD testcase “Radiver 2” [26], extending the experimental data base of the testcase “Radiver” published in 2003 by Ziegler [31].

An investigation of a high-performance centrifugal compressor with a variable map width enhancement slot for proton exchange membrane fuel cell systems in commercial vehicle application

2020 ◽  
Vol 235 (1) ◽  
pp. 288-300
Author(s):  
Jianjiao Jin ◽  
Jianfeng Pan ◽  
Zhigang Lu ◽  
Qingrui Wu ◽  
Lizhong Xu
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Centrifugal Compressor ◽  
Proton Exchange Membrane ◽  
Performance Test ◽  
High Efficiency ◽  
Proton Exchange ◽  
Surge Margin ◽  
Compressor Performance ◽  
Exchange Membrane

Maintaining required performance and rated power output of proton exchange membrane fuel cells while reducing fuel consumption demands and improving efficiencies at the largest parasitic work loss contributor, namely the air compressor. In this paper, we built a high-efficiency one-dimensional match model of centrifugal compressor for proton exchange membrane fuel cells first, which was based on the fuel cell air supply system and the optimal trim factor. And then a variable map width enhancement slot design adjusted by a closed ring was first introduced to extend the surge margin and keep high efficiency. Finally, the compressor with a variable map width enhancement slot was validated at a compressor performance rig and a fuel cell simulation system. The results from compressor performance test rig indicate that the compressor peak efficiency is as high as 77% and the surge margin is enhanced by about 28.1∼ 42.7 %. The simulation results of the fuel cell system indicate the maximum power consumption of the compressor and the H2 consumption of comprehensive adapted world transient vehicle cycle are reduced by nearly 1.6 kW and 4.86%, respectively, in comparison with the baseline screw compressor.

An Investigation Into the Effect of Clearance Aspect Ratio on the Performance of a Variable Geometry Vaned Diffuser for Automotive Turbocharger Application

2020 ◽  
Author(s):  
Lee Gibson ◽  
Stephen Spence ◽  
Sung In Kim ◽  
Charles Stuart ◽  
Martin Schwitzke ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Width Ratio ◽  
Boost Pressure ◽  
Variable Geometry ◽  
Peak Efficiency ◽  
Vaned Diffuser ◽  
Vortical Structures ◽  
Compressor Performance ◽  
Compressor Map ◽  
Compressor Efficiency

Abstract The current state-of-the-art in radial compressor design for automotive turbocharger applications utilize impellers with a high trailing edge backsweep angle and a vaneless diffuser to provide a high boost pressure over a wide operating range. A unique feature of this type of design is that the peak efficiency island is typically located near the choke side of the compressor map. As such, the compressor efficiency is generally satisfactory when the engine is operating at high speed, such as the rated power condition. However, at low speeds the engine operating line is located close to the compressor surge line where the efficiency is generally modest. Thus, there is a need to improve the compressor efficiency at low engine speeds without compromising performance near the choke side of the map or the overall map width. Variable geometry devices have shown good potential to improve the compressor performance without a compromise in map width. In general, variability is achieved by moving walls or rotating vanes to best suit the flow conditions for a given mass flow rate. In order for this to be practically realised, a clearance or gap is required between the stationary and moving parts. This ultimately gives rise to leakage flows within the compressor stage and generally results in a lower achievable efficiency relative to the fixed geometry configuration. A study by the authors on an on/off type variable geometry vaned diffuser identified significant loss mechanisms due to the clearances required for the vanes to slide in to and out of the main flow path. Moreover, the endwall position of the clearance was found to have a marked impact on the compressor stability and peak efficiency. This paper assesses the effect of the clearance depth to width ratio (or aspect ratio) at different endwall positions with the aim of identifying an appropriate geometry and position to approach an optimised design. Steady-state Reynolds-Averaged Navier-Stokes (RANS) simulations were performed using ANSYS CFX at three operating speeds to obtain a broad sense of the effect of the clearance aspect ratio on the compressor performance. It was found that a high value of aspect ratio enabled the formation of large vortical structures in the vaned diffuser. The mixing between the core flow and the vortical structures resulted in significant losses in the vaned diffuser and affected the compressor map width differently depending on the endwall position.

Experimental Investigation of Inlet Distortion in a 4.5-Stage Axial Compressor

2020 ◽  
Author(s):  
Oliver Reutter ◽  
Gerd Enders ◽  
Theo Dabrock ◽  
Andreas Peters
Keyword(s):  
Experimental Investigation ◽  
Gas Turbines ◽  
Axial Compressor ◽  
Metal Plate ◽  
Axial Compressors ◽  
Transonic Compressor ◽  
Inlet Distortion ◽  
Surge Margin ◽  
Small Influence ◽  
Compressor Map

Abstract Inlet distortion is a subject of increasing interest in compressors over the last years. Circumferential inhomogeneities can significantly influence the behavior and the aeroelastic response of transonic compressors in gas turbines in the field of airplane propulsion as well as power generation. The circumferential inhomogeneities can result from boundary layer ingestion as planned in many future airplane concepts or from restrictions of the space available leading to short aerodynamically unfavorable intakes. As modern front rows of axial compressors react more and more sensitive to inhomogeneities because of the thinner profiles in the transonic flow regime, understanding the behavior is vital. Therefore, an experimental investigation of the inlet distortion effects on a 4.5 stage axial transonic compressor, Rig250, which is representative of the front stages of a modern high pressure compressor, has been investigated at DLR Cologne. The inhomogeneity is a total pressure distortion which is applied to the inflow upstream of the strut and the swan neck. The distortion is achieved by a perforated metal plate which can be rotated by 360° at its position. Thereby traverse measurements are possible, which allow a better understanding of the effects of the flow as the sensor positions on the casing and on the blades and vanes are fixed. As these traverses take longer time for measuring only some points are measured with traverses. The compressor has been tested with and without this inlet distortion to get a direct comparison. On the compressor map the 100 % speed line up to surge has been investigated. The inlet distortion shows only a small influence on the surge margin.

scholarly journals Axial Compressor Mean-Line Analysis: Choking Modelling and Fully-Coupled Integration in Engine Performance Simulations

2021 ◽  
Vol 6 (1) ◽  
pp. 4
Author(s):  
Ioannis Kolias ◽  
Alexios Alexiou ◽  
Nikolaos Aretakis ◽  
Konstantinos Mathioudakis
Keyword(s):  
Axial Compressor ◽  
Engine Performance ◽  
Engine Model ◽  
Multi Stage ◽  
Transient Simulations ◽  
Full Knowledge ◽  
Compressor Performance ◽  
First Time ◽  
Performance Calculation ◽  
Fully Coupled

A mean-line compressor performance calculation method is presented that covers the entire operating range, including the choked region of the map. It can be directly integrated into overall engine performance models, as it is developed in the same simulation environment. The code materializing the model can inherit the same interfaces, fluid models, and solvers, as the engine cycle model, allowing consistent, transparent, and robust simulations. In order to deal with convergence problems when the compressor operates close to or within the choked operation region, an approach to model choking conditions at blade row and overall compressor level is proposed. The choked portion of the compressor characteristics map is thus numerically established, allowing full knowledge and handling of inter-stage flow conditions. Such choking modelling capabilities are illustrated, for the first time in the open literature, for the case of multi-stage compressors. Integration capabilities of the 1D code within an overall engine model are demonstrated through steady state and transient simulations of a contemporary turbofan layout. Advantages offered by this approach are discussed, while comparison of using alternative approaches for representing compressor performance in overall engine models is discussed.

Compressor Maps and Coupling: Symmetry, Paradox, and Clarity

2021 ◽  
Author(s):  
Benjamin Iwrey
Keyword(s):  
Temperature Ratio ◽  
Independent Variables ◽  
Dependent Variables ◽  
In Series ◽  
Compressor Performance ◽  
Multistage Compressor ◽  
Compressor Map ◽  
Flow Flux ◽  
Operating Points ◽  
Corrected Flow

Abstract The most common compressor map framework, referred to here as the β-framework, will be shown to suffer from limitations that grow more troublesome in the multiple-map environment. When maps are coupled in series in the β-framework, it is very common to find operating points that are physically unrealizable, but these cannot generally be avoided without first generating them. A feasible situation is described in which the β-framework leads to an apparent physical paradox. In the proposed S-framework, the map itself is recast in terms of independent variables (corrected speed and exit corrected flow) and dependent variables (inlet corrected flow and temperature ratio). The propagation of information in map coupling is split into an upstream-marching corrected flow ‘flux’ and a downstream-marching temperature ‘flux’. Finding the equilibrium operating point requires only finding a simple intersection between curves. The S-framework is then developed further into a more compact S’-framework that exhibits a natural set of qualitative symmetries. The S- and S’-frameworks are shown to simplify compressor map expression, resolve the problems shown with the β-framework, and aid intuition with regard to off-design phenomena. The resolution of the paradox using the S’-framework is a new description of multistage compressor performance hysteresis.

Compressor Performance 2D Modelling at Reverse Flow Conditions

2010 ◽  
Author(s):  
L. Gallar ◽  
I. Tzagarakis ◽  
V. Pachidis ◽  
R. Singh
Keyword(s):  
Experimental Data ◽  
Reverse Flow ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Engine Performance ◽  
Two Dimensional ◽  
Flow Conditions ◽  
Compressor Surge ◽  
Compressor Performance ◽  
Shaft Failure

After a shaft failure the compression system of a gas turbine is likely to surge due to the heavy vibrations induced on the engine after the breakage. Unlike at any other conditions of operation, compressor surge during a shaft over-speed event is regarded as desirable as it limits the air flow across the engine and hence the power available to accelerate the free turbine. It is for this reason that the proper prediction of the engine performance during a shaft over-speed event claims for an accurate modelling of the compressor operation at reverse flow conditions. The present study investigates the ability of the existent two dimensional algorithms to simulate the compressor performance in backflow conditions. Results for a three stage axial compressor at reverse flow were produced and compared against stage by stage experimental data published by Gamache. The research shows that due to the strong radial fluxes present over the blades, two dimensional approaches are inadequate to provide satisfactory results. Three dimensional effects and inaccuracies are accounted for by the introduction of a correction parameter that is a measure of the pressure loss across the blades. Such parameter is tailored for rotors and stators and enables the satisfactory agreement between calculations and experiments in a stage by stage basis. The paper concludes with the comparison of the numerical results with the experimental data supplied by Day on a four stage axial compressor.

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