Investigation of variable geometry orifice design for improving centrifugal compressor low-end performance and stable operating range

2021 ◽  
pp. 095441002110476
Author(s):  
Ben Zhao ◽  
Qingjun Zhao ◽  
Xiaorong Xiang ◽  
Wei Zhao ◽  
Jianzhong Xu
Keyword(s):  
Numerical Simulations ◽  
Centrifugal Compressor ◽  
Control Device ◽  
Design Parameters ◽  
Variable Geometry ◽  
Flow Area ◽  
Stall Margin ◽  
Setting Angle ◽  
Compressor Inlet ◽  
Two Parameters

Active control of the inlet flow area in a centrifugal compressor is a method to improve compressor aerodynamic performance and stall margin. As a core part of the area control device, the variable geometry orifice is investigated and its two key design parameters are analyzed in detail, the setting angle of the orifice with respect to the shroud casing and the radial height of the orifice to the shroud casing from the orifice inner rim. This paper proposes a physics-based equation that describes the relationship of the two parameters with compressor mass flow rate and then validates the equation using numerical simulations. As far as the setting angle, the physics-based equation suggests not to be larger than 90°. The numerical results not only validate the physics-based equation but also show the most optimal angle of 78°. In terms of the orifice height, both the physics-based equation and the numerical simulations suggest an active height control of orifice in the compressor inlet duct.

Proposal and Experimental Verification of Design Guidelines for Centrifugal Compressor Impellers With Curvilinear Element Blades to Improve Compressor Performance

2014 ◽  
Author(s):  
Kiyotaka Hiradate ◽  
Kazuyuki Sugimura ◽  
Hiromi Kobayashi ◽  
Toshio Ito ◽  
Hideo Nishida
Keyword(s):  
Velocity Distribution ◽  
Coordinate System ◽  
Numerical Simulations ◽  
Centrifugal Compressor ◽  
Design Guidelines ◽  
Compressor Stage ◽  
Stall Margin ◽  
Cylindrical Coordinate ◽  
Forward Part ◽  
Stage Efficiency

This study numerically and experimentally examines the effects of applying curvilinear element blades to fully-shrouded centrifugal impellers on the performance of the centrifugal compressor stages. The design suction coefficient of the target impellers was 0.073. Our previous study confirmed that the application of curvilinear element blades could improve the stage efficiency of similar types of centrifugal compressors. However, a detailed explanation of the relation between the stall margin and the application of the curvilinear element blades remains to be given. The purpose of this study is to investigate the effects of using these blades on the impeller flow field and the stall margin in further detail. The curvilinear element blades we developed for centrifugal turbomachinery were defined by the coordinate transformations between a revolutionary flow-coordinate system and a cylindrical coordinate system. All the blade sections in the transferred cylindrical coordinate system were moved and stacked spanwise in accordance with the given “lean profile,” which meant the spanwise distribution profile of movement of the blade sections, to form a new leaned blade surface. The effects of the curvilinear element blades on the impeller flowfield were investigated by conducting numerical simulations using this method. We next considered the optimum design guidelines for impellers with curvilinear element blades. Then we designed a new impeller using these design guidelines and evaluated the performance improvement of a new compressor stage by conducting numerical simulations. As mentioned in several papers, we numerically confirmed that curvilinear element blades with a negative tangential lean profile improved the velocity distribution and stage efficiency because they help to suppress the secondary flows in the impeller. The negative tangential lean mentioned in this paper represents the lean profile in which the blade hub end leans forward in the direction of the impeller rotation compared to the blade shroud end. At the same time, we also found that the stall margin of these impellers deteriorated due to the increase in relative velocity deceleration near the suction surface of the shroud in the forward part of the impeller. Therefore, we propose new design guidelines for impellers with the curvilinear element blades by applying a negative tangential lean to line element blades in which the blade loading of the shroud side in the forward part of the impeller is reduced. We confirmed from the numerical simulation results that the performance of the new compressor stage improved compared to that in the corresponding conventional one. The new design guidelines for the curvilinear element blades were experimentally verified by comparing the performance of the new compressor stage with the corresponding conventional one. The measured efficiency of the new compressor stage was 2.4 % higher than that of the conventional stage with the stall margin kept comparable. A comparison of the measured velocity distributions at the impeller exit showed that the velocity distribution of the new impeller was much more uniform than that of the conventional one.

Power and efficiency optimization for combined Brayton and two parallel inverse Brayton cycles. Part 2: Performance optimization

2008 ◽  
Vol 222 (3) ◽  
pp. 405-413 ◽  
Author(s):  
W Zhang ◽  
L Chen ◽  
F Sun
Keyword(s):  
Conversion Efficiency ◽  
Power Output ◽  
Performance Optimization ◽  
Pressure Ratio ◽  
Thermal Conversion ◽  
Design Parameters ◽  
Flow Area ◽  
Compressor Inlet ◽  
Mass Flowrate ◽  
Top Cycle

The power and efficiency of the open combined Brayton and two parallel inverse Brayton cycles are analysed and optimized based on the model established using finite-time thermodynamics in Part 1 of the current paper by adjusting the compressor inlet pressure of the two parallel inverse Brayton cycles, the mass flowrate and the distribution of pressure losses along the flow path. It is shown that the power output has a maximum with respect to the compressor inlet pressures of the two parallel inverse Brayton cycles, the air mass flowrate or any of the overall pressure drops, and the maximized power output has an additional maximum with respect to the compressor pressure ratio of the top cycle. The power output and the thermal conversion efficiency have the maximum values when the mass flowrates of the first and the second inverse Brayton cycles are the same. When the optimization is performed with the constraints of a fixed fuel flowrate and the power plant size, the power output and thermal conversion efficiency can be maximized again by properly allocating the fixed overall flow area among the compressor inlet of the top cycle and the turbine outlets of the two parallel inverse Brayton cycles. The numerical examples show the effects of design parameters on the power output and heat conversion efficiency.

scholarly journals Research and development of the structure of a vortex heat generator by the method of mathematical modeling

2021 ◽  
Vol 1 (1(57)) ◽  
pp. 39-43
Author(s):  
Vadim Yaris ◽  
Ivan Kuzyayev ◽  
Valeriy Nikolsky ◽  
Viktor Ved ◽  
Chlens Peter ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Energy Efficiency ◽  
Rectangular Cross Section ◽  
Geometric Parameters ◽  
Design Parameters ◽  
Variable Geometry ◽  
Flow Area ◽  
Heat Generator ◽  
Vortex Zone ◽  
Working Space

The object of research is a mathematical model of a new design of a vortex heat generator with translational-rotational flow in a variable geometry working space. One of the most problematic areas in the development of new and promising designs of heat generators by the method of physical modeling is the search for its optimal operating-technological and instrumental-design parameters. The implementation of a preliminary analysis of such structures by the method of mathematical modeling will significantly reduce the time and material costs for the development of promising designs of heat generators. The studies of the design of the new vortex heat generator, carried out by the method of mathematical modeling, made it possible to determine the range of its operation, to evaluate the operating-technological and hardware-design parameters that affect the efficiency of work. Studies of the hydrodynamics of the translational-rotational motion of a viscous fluid flow in the working space of a new vortex heat generator with a variable geometry of the working space made it possible to determine the critical velocity and pressure, the influence of the geometric parameters of the device on the generation of vortices that promote cavitation. Model studies were carried out in the range of fluid load changes in the range from 0.001 m3/s to 0.01 m3/s. The study of changes in the velocity field in the channels was carried out for the geometry of the channel with a taper angle  from 0° to 25°. The width of the working channel of the space Wn varied in the range of 130, 70 and 40 mm. It has been established that a good axial symmetry and smoothness of the coolant flow in the vortex zone along the swirler screw provides the coolant inlet through a nozzle with a rectangular cross-section. The dependence of the influence of the flow area of the nozzle for introducing the coolant into the vortex zone on the energy efficiency of the vortex apparatus as a whole is found experimentally. The research carried out makes it possible to design vortex heat generators with geometric parameters that meet modern energy efficiency requirements. The geometry of the swirler screw is determined, which increases the efficiency of the heat generator by 35 % in comparison with similar designs of vortex heat generators given in the literature.

The Influence of Inlet Flow Distortion on the Performance of a Centrifugal Compressor and the Development of Improved Inlet Using Numerical Simulations—Part II: Development of Improved Inlet for a Centrifugal Compressor Using Numerical Simulations

2000 ◽  
Author(s):  
Yunbae Kim ◽  
Abraham Engeda ◽  
Ron Aungier ◽  
Greg Direnzi
Keyword(s):  
Numerical Simulations ◽  
Centrifugal Compressor ◽  
Curvature Radius ◽  
Flow Properties ◽  
Inlet Pipe ◽  
Flow Distortion ◽  
Cross Sectional ◽  
Inlet System ◽  
Compressor Inlet ◽  
Compressor Performance

Abstract Part I of this paper reported the experimental investigation on the effect of the curved inlet pipe flow distortion on a centrifugal compressor performance, which motivated the need of a new inlet design as well as a clear picture of the detailed flow field in the existing inlet design using numerical simulations. In Part II, new designs of different inlet systems as well as the design methods are discussed based on the comparison of flow properties at pipe exit of each design. The goal of the compressor inlet system design is to reduce the secondary flow and provide uniform flow for a compressor. Two design approaches are reported in this paper, one of which is the location of vanes and the other is the length of curvature radius, resulting in four new designs. The vanes are spaced in such a way that each passage shares the same pressure difference in radial direction. Numerical simulation results are presented in terms of mass averaged parameters and flow structures on the exit cross-sectional area. The design of original bend pipe with two vanes inside shows advantages over others.

Proposal and Experimental Verification of Design Guidelines for Centrifugal Compressor Impellers With Curvilinear Element Blades to Improve Compressor Performance

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Kiyotaka Hiradate ◽  
Hiromi Kobayashi ◽  
Kazuyuki Sugimura ◽  
Toshio Ito ◽  
Hideo Nishida
Keyword(s):  
Velocity Distribution ◽  
Coordinate System ◽  
Numerical Simulations ◽  
Centrifugal Compressor ◽  
Design Guidelines ◽  
Cylindrical Coordinate System ◽  
Compressor Stage ◽  
Stall Margin ◽  
Cylindrical Coordinate ◽  
Forward Part

This study numerically and experimentally examines the effects of applying curvilinear element blades to fully shrouded centrifugal impellers on the performance of the centrifugal compressor stages. The curvilinear element blades we developed for centrifugal turbomachinery were defined by the coordinate transformations between a revolutionary flow-coordinate system and a cylindrical coordinate system. All the blade sections in the transferred cylindrical coordinate system were moved and stacked spanwise in accordance with the given “lean profile,” which meant the spanwise distribution profile of movement of the blade sections, to form a new leaned blade surface. The effects of the curvilinear element blades on the impeller flowfield were investigated using numerical simulations, and the optimum design guidelines for impellers with curvilinear element blades were considered. Then, a new impeller using these design guidelines was designed and the performance improvement of a new compressor stage was evaluated by numerical simulations. As mentioned in several papers, we numerically confirmed that curvilinear element blades with a negative tangential lean (TGL) profile improved the velocity distribution and stage efficiency because they help to suppress the secondary flows in the impeller. The negative TGL mentioned in this paper represents the lean profile in which the blade hub end leans forward in the direction of the impeller rotation compared to the blade shroud end. At the same time, we also found that the stall margin of these impellers deteriorated due to the increase in relative velocity deceleration near the suction surface of the shroud in the forward part of the impeller. Therefore, we propose new design guidelines for impellers with the curvilinear element blades by applying a negative TGL to line element blades in which the blade loading of the shroud side in the forward part of the impeller is reduced. We confirmed from the numerical simulation results that the performance of the new compressor stage improved compared to that in the corresponding conventional one. The new design guidelines for the curvilinear element blades were experimentally verified by comparing the performance of the new compressor stage with the corresponding conventional one. The measured efficiency of the new compressor stage was 2.4% higher than that of the conventional stage with the stall margin kept comparable. A comparison of the measured velocity distributions at the impeller exit showed that the velocity distribution of the new impeller was much more uniform than that of the conventional one.

scholarly journals AC Current Ripple in Three-Phase Four-Leg PWM Converters with Neutral Line Inductor

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1430
Author(s):  
Aleksandr Viatkin ◽  
Riccardo Mandrioli ◽  
Manel Hammami ◽  
Mattia Ricco ◽  
Gabriele Grandi
Keyword(s):  
Numerical Simulations ◽  
Pulse Width Modulation ◽  
Neutral Line ◽  
Experimental Tests ◽  
Performance Comparison ◽  
Design Parameters ◽  
Switching Frequency ◽  
Three Phase ◽  
Ac Current ◽  
Current Ripple

This paper presents a comprehensive study of peak-to-peak and root-mean-square (RMS) values of AC current ripples with balanced and unbalanced fundamental currents in a generic case of three-phase four-leg converters with uncoupled AC interface inductors present in all three phases and in neutral. The AC current ripple characteristics were determined for both phase and neutral currents, considering the sinusoidal pulse-width modulation (SPWM) method. The derived expressions are simple, effective, and ready for accurate AC current ripple calculations in three- or four-leg converters. This is particularly handy in the converter design process, since there is no need for heavy numerical simulations to determine an optimal set of design parameters, such as switching frequency and line inductances, based on the grid code or load restrictions in terms of AC current ripple. Particular attention has been paid to the performance comparison between the conventional three-phase three-leg converter and its four-leg counterpart, with distinct line inductance values in the neutral wire. In addition to that, a design example was performed to demonstrate the power of the derived equations. Numerical simulations and extensive experimental tests were thoroughly verified the analytical developments.

Automatic Three-Dimensional Optimisation of a Modern Tandem Compressor Vane

2014 ◽  
Author(s):  
R. C. Schlaps ◽  
S. Shahpar ◽  
V. Gümmer
Keyword(s):  
Pressure Ratio ◽  
Three Dimensional ◽  
Trust Region ◽  
Automatic Generation ◽  
Navier Stokes ◽  
Design Parameters ◽  
High Fidelity ◽  
Stall Margin ◽  
Design Choice ◽  
Multipoint Approximation

In order to increase the performance of a modern gas turbine, compressors are required to provide higher pressure ratio and avoid incurring higher losses. The tandem aerofoil has the potential to achieve a higher blade loading in combination with lower losses compared to single vanes. The main reason for this is due to the fact that a new boundary layer is generated on the second blade surface and the turning can be achieved with smaller separation occurring. The lift split between the two vanes with respect to the overall turning is an important design choice. In this paper an automated three-dimensional optimisation of a highly loaded compressor stator is presented. For optimisation a novel methodology based on the Multipoint Approximation Method (MAM) is used. MAM makes use of an automatic design of experiments, response surface modelling and a trust region to represent the design space. The CFD solutions are obtained with the high-fidelity 3D Navier-Stokes solver HYDRA. In order to increase the stage performance the 3D shape of the tandem vane is modified changing both the front and rear aerofoils. Moreover the relative location of the two aerofoils is controlled modifying the axial and tangential relative positions. It is shown that the novel optimisation methodology is able to cope with a large number of design parameters and produce designs which performs better than its single vane counterpart in terms of efficiency and numerical stall margin. One of the key challenges in producing an automatic optimisation process has been the automatic generation of high-fidelity computational meshes. The multi block-structured, high-fidelity meshing tool PADRAM is enhanced to cope with the tandem blade topologies. The wakes of each aerofoil is properly resolved and the interaction and the mixing of the front aerofoil wake and the second tandem vane are adequately resolved.

Simultaneous Optimal Design of the Lyapunov-Based Semi-Active Control and the Semi-Active Vibration Control Device: Inverse Lyapunov Approach

2010 ◽  
Author(s):  
Kazuhiko Hiramoto ◽  
Taichi Matsuoka ◽  
Akira Fukukita ◽  
Katsuaki Sunakoda
Keyword(s):  
Optimal Design ◽  
Lyapunov Function ◽  
Vibration Control ◽  
Active Control ◽  
Control Device ◽  
Ball Screw ◽  
Design Parameters ◽  
Resistance Force ◽  
Control Law ◽  
Lyapunov Approach

We address a simultaneous optimal design problem of a semi-active control law and design parameters in a vibration control device for civil structures. The Vibration Control Device (VCD) that is being developed by authors is used as the semi-active control device in the present paper. The VCD is composed of a mechanism of a ball screw with a flywheel for the inertial resistance force and an electric motor with an electric circuit for the damping resistance force. A new bang-bang type semi-active control law referred to as Inverse Lyapunov Approach is proposed as the semi-active control law. In the Inverse Lyapunov Approach the Lyapunov function is searched so that performance measures in structural vibration control are optimized in the premise of the bang-bang type semi-active control based on the Lyapunov function. The design parameters to determine the Lyapunov function and the design parameters of the VCD are optimized for the good performance of the semi-active control system. The Genetic Algorithm is employed for the optimal design.

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