A Novel One-Dimensional–Three-Dimensional Coupled Method to Predict Surge Boundary of Centrifugal Compressors

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Meijie Zhang ◽  
Xinqian Zheng ◽  
Qiangqiang Huang ◽  
Zhenzhong Sun
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Tangential Velocity ◽  
Engine Performance ◽  
Simulation Method ◽  
Dynamic Force ◽  
Centrifugal Compressors ◽  
Compression System ◽  
One Dimensional ◽  
Coupled Method

Compression systems are widely employed in gas turbine engines, turbocharged engines, and industry compression plants. The stable work of compression systems is an essential precondition for engine performance and safety. A compression system in practice usually consists of upstream and downstream pipes, compressors, plenums and throttles. When a compression system encounters the surge, the flows in the compressor present complex three-dimensional patterns but the flows of other components might present relatively simple one-dimensional patterns. Based on these flow characteristics, this paper proposes a novel simulation method, where one-dimensional and three-dimensional (1D–3D) calculations are coupled, to predict the surge boundary of centrifugal compressors. To validate this method, a high-speed centrifugal compressor is studied both by the proposed 1D–3D coupled method and experimentally. The results show that the differences between the predicted and experimentally determined stable flow range are lower than 5% until the Mach number of blade outlet tip tangential velocity reaches around 1.3. Besides, this method can correctly predict the instantaneous compressor performance during the surge cycle, so it can also be used to explore the surge mechanism and evaluate the blade dynamic force response in the future.

scholarly journals Quasi-two-dimensional approximation for numerical simulation of flows in engine ducts

2019 ◽  
Author(s):  
V. Vlasenko ◽  
A. Shiryaeva
Keyword(s):  
High Speed ◽  
Fuel Injection ◽  
Three Dimensional ◽  
Preliminary Design ◽  
Two Dimensional ◽  
Combustion Chambers ◽  
New Approach ◽  
One Dimensional ◽  
Dimensional Approximation ◽  
3D Flows

New quasi-two-dimensional (2.5D) approach to description of three-dimensional (3D) flows in ducts is proposed. It generalizes quasi-one-dimensional (quasi-1D, 1.5D) theories. Calculations are performed in the (x; y) plane, but variable width of duct in the z direction is taken into account. Derivation of 2.5D approximation equations is given. Tests for verification of 2.5D calculations are proposed. Parametrical 2.5D calculations of flow with hydrogen combustion in an elliptical combustor of a high-speed aircraft, investigated within HEXAFLY-INT international project, are described. Optimal scheme of fuel injection is found and explained. For one regime, 2.5D and 3D calculations are compared. The new approach is recommended for use during preliminary design of combustion chambers.

Experiment and Numerical Simulation of Extrudate Swell in the Polymer Extrusion Process

2011 ◽  
Vol 314-316 ◽  
pp. 401-404 ◽  
Author(s):  
Min Zhang ◽  
Chuan Zhen Huang ◽  
Guo Wen Chen ◽  
Yu Xi Jia
Keyword(s):  
Numerical Simulation ◽  
High Speed ◽  
Three Dimensional ◽  
Simulation Method ◽  
Extrusion Process ◽  
High Speed Photography ◽  
The Finite Element Method ◽  
Polymer Extrusion ◽  
Extrudate Swell ◽  
Rate Profile

The extrudate swell of the polymer extrusion process was studied with the experiment and simulation method. The extrudate swell process was recorded by the high-speed photography apparatus. The swell rate at the different time was calculated. It is found that the extrudate swell rate increase at the first five seconds. The maximum swell rate is about 4.37%. The three-dimensional numerical simulation model of the experiment die path was founded. The extrusion process including the extrudate swell was simulated used the Finite Element Method. Such simulated results as the velocity vector, the shear rate profile and the end of the swell zone were analyzed. The extrudate swell end got by the simulation is similar with the experiment result.

MotoGP 2007: Criteria for Engine Optimization

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
Enrico Mattarelli
Keyword(s):  
High Speed ◽  
Fluid Dynamic ◽  
Weight Ratio ◽  
Engine Performance ◽  
Real Data ◽  
Mechanical Efficiency ◽  
Point Of View ◽  
One Dimensional ◽  
Four Cylinders ◽  
Technical Regulations

The paper proposes some design criteria for the MotoGP engines, complying with the FIM 2007 Technical Regulations. Five configurations have been considered: engines with three cylinders in line and four cylinders in line, and three V engines with four, five, and six cylinders. All the analyzed solutions have been optimized from a fluid-dynamic point of view by means of one dimensional engine cycle simulations. Then, the engines are compared in terms of full load performance at steady conditions. Finally, the influence of engine performance, along with operation regularity and motorbike weight, is assessed by means of a lap time simulator, developed by the author on the base of real data. The best configurations turned out to be the four-cylinder engines, while three-cylinder and five-cylinder engines are quite penalizing. The key of the four-cylinder engines success is their good breathing capability and mechanical efficiency at high speed, yielding an optimum power-to-weight ratio, associated with a good engine regularity, i.e., a smooth response to throttle angle variations.

The Performance Simulation and Optimization Research on Intake Port of Locomotive Diesel Engine

2012 ◽  
Vol 443-444 ◽  
pp. 1007-1013
Author(s):  
Hong Jiang Cui ◽  
Ming Hai Li ◽  
Ying Guan
Keyword(s):  
Diesel Engine ◽  
Flow Condition ◽  
Discharge Coefficient ◽  
Cfd Simulation ◽  
Air Flow ◽  
Three Dimensional ◽  
Engine Performance ◽  
Simulation Method ◽  
Intake Port ◽  
Simulation And Optimization

.In order to manufacture high quality intake port with bigger discharge coefficient and appropriate swirl ratio for diesel engine performance improvement, intake port tests and CFD simulation method were combined together to optimize its structure. The three-dimensional CAD model of intake port was built and was putted into AVL–FIRE platform to do CFD simulation with appropriate turbulence model and calculation method. The detailed air flow information was obtained by CFD simulation. After analyzing, two optimization programs were discussed. This research shows that CFD simulation is a powerful method to design diesel engine intake port; air flow condition is complex in the intake port; intake port structure optimization can increase the discharge coefficient and improve the air flow condition.

A Fast Gas Turbine Engine Performance Analysis Tool Able to Capture Three Dimensional Effects

2007 ◽  
Author(s):  
Ioannis Templalexis ◽  
Pericles Pilidis ◽  
Vassilios Pachidis ◽  
Petros Kotsiopoulos
Keyword(s):  
Three Dimensional ◽  
Axial Flow ◽  
Engine Performance ◽  
Flow Simulation ◽  
Simulation Method ◽  
Flow Profile ◽  
Flow Distortion ◽  
Performance Simulation ◽  
Turbine Engine ◽  
The Impact

Given the current level of computational resources that are readily available, three dimensional (3-D) gas turbine engine performance simulation remains extremely time consuming. The current paper presents a synthesis of existing flow simulation methods coupled together in the form of a new software package. The software is able to assess the impact of a 3-D flow profile at the intake inlet on engine performance, demanding relatively low computational resources. More precisely four flow simulation techniques are employed, represented respectively by four individual stand alone software sub-modules. 3-D Vortex Lattice Method (VLM) is used to simulate the intake flow. Subsequently the intake outlet 3-D flow profile is decomposed into a radial and a circumferential component. For the compressor performance simulation, that receives those components as inlet boundary conditions, a two dimensional (2-D) Streamline Curvature (SLC) simulation method coupled with an extended parallel compressor model is used. SLC addresses the impact of the radial flow distortion, whereas the extended parallel compressor model examines the impact of circumferential flow distortion on engine performance. The results of the above analysis are stored into an intake-compressor performance characteristic map, which is then fed into a zero dimensional (0-D) performance simulation tool in order to evaluate the overall impact of the intake inlet distorted flow on engine performance. The paper is divided into two major sections. The first one presents the individual flow simulation techniques, together with the corresponding software modules. A short summary of each method is given first and then the software module is described, followed by brief comments on the validation results that have been already published. The section in concluded by the description of the synthesized software. The second major section deals with the application of the synthesized simulation method on a turbojet engine. A generic turbojet engine has been chosen mounted behind a generic intake, given the lack of relevant experimental results. The engine has a four stage axial flow compressor driven by a single stage axial flow turbine, followed by a converging nozzle. 3-D total pressure profiles were imposed at the intake inlet and several comparative graphs of engine’s performance parameters between “clean” and distorted inlet flow conditions are given. The paper is concluded with a discussion on software’s abilities and weaknesses as well as on its potential future expansion.

Rationalization of Empirical Loss Coefficients and Their Application in One Dimensional Performance Prediction Procedures for Centrifugal Compressors

1978 ◽  
Author(s):  
A. Whitfield
Keyword(s):  
Performance Prediction ◽  
Essential Feature ◽  
Three Dimensional ◽  
Separated Flow ◽  
General Assumption ◽  
Centrifugal Compressors ◽  
Loss Mechanism ◽  
One Dimensional ◽  
Adiabatic Flow ◽  
Dimensional Flow

The flow through centrifugal compressors is often highly separated and fully three-dimensional. Modern computing techniques have not yet provided the ability to predict this three-dimensional separated flow. The design engineer has the need of a relatively simple performance prediction procedure in order to assess the potential of any proposed design. Consequently, a number of performance prediction procedures, with the general assumption of one-dimensional adiabatic flow, have been published. A common and essential feature of all these procedures is the use of empirical parameters in order to expand the one-dimensional flow into a description of the fully three-dimensional flow. These empirical parameters usually describe the loss mechanism and the flow deviation in any duct. Presented in footnote is a one-dimensional procedure which separated the fundamental gas dynamics from the empiricism used. Consequently, it is a relatively simple matter to apply alternative empirical parameters, and, more importantly, it is also possible for the design engineer to readily apply empirical relationships built up from his own experience. Unfortunately, numerous techniques are used to define the losses, and it may be necessary for the design engineer to redefine his own data in terms compatible with the computer program available to him.

Jet motion and fiber properties arising from a parallel electric field in melt-electrospinning

2020 ◽  
pp. 004051752096419
Author(s):  
Xueqin Li ◽  
Yuansheng Zheng ◽  
Xiaoqi Mu ◽  
Binjie Xin ◽  
Lantian Lin
Keyword(s):  
Electric Field ◽  
High Speed ◽  
Three Dimensional ◽  
Great Influence ◽  
Simulation Method ◽  
High Speed Photography ◽  
Outer Diameter ◽  
Electrospinning Technique ◽  
Fiber Properties ◽  
Melt Electrospinning

It is well known that the electric field has a great influence on the diameter and properties of fiber prepared via the melt-electrospinning technique. In this paper, two parallel metal discs were introduced to create a controllable electric field in the experiments. In addition, a three-dimensional electric field was calculated by the numerical simulation method and the jet motion was captured by taking advantage of high-speed photography technology. The influences of electric field distribution on the fiber jet, fiber diameter, fiber mat area and fiber crystallinity were studied in an in-depth and systematical manner. Both whipping amplitude and whipping frequency were also used to describe the characteristics of the jet. The above-mentioned results have proven that increasing the distance between the two parallel metal discs leads to the decrease of electric field intensity and the increase of electric field action time on the fiber, which together determine the diameter and crystallinity of the fiber. With the increase of the outer diameter of the upper disc, the distribution of the electric field becomes more uniform, making it capable of steadily controlling the behavior of the jet, and thus effectively reducing the diameter of the fiber and improving the crystallinity of the fiber.

Oil-Free Automotive Turbochargers: Drag Friction and On-Engine Performance Comparisons to Oil-Lubricated Commercial Turbochargers

2016 ◽  
Author(s):  
Keun Ryu ◽  
Zachary Ashton
Keyword(s):  
High Speed ◽  
Engine Performance ◽  
Large Mass ◽  
Viscous Drag ◽  
Dynamic Force ◽  
Rotor Speed ◽  
Dimensional Changes ◽  
Foil Bearings ◽  
Speed Test ◽  
Lower Viscosity

Oil-free bearings for automotive turbochargers (TCs) offer unique advantages eliminating oil-related catastrophic TC failures (oil coking, severe bearing wear/seizure, and significant oil leakage, for example) while increasing overall system reliability and reducing maintenance costs. The main objective of the current investigation is to advance the technology of the gas foil bearings (GFBs) for automotive TCs by demonstrating their reliability, durability, and static/dynamic force characteristics desirable in extreme speed and temperature conditions. The paper compares drag friction and on-engine performances of an oil-free TC supported on GFBs against an oil-lubricated commercial production TC with identical compressor and turbine wheels. Extensive coast-down and fast acceleration TC rotor speed tests are conducted in a cold-air driven high-speed test cell. Rotor speed coast-down tests demonstrate that the differences in the identified rotational viscous drag coefficients and drag torques between the oil-free and production TCs are quite similar. In addition, rotor acceleration tests show that the acceleration torque of the oil-free TC rotor, when airborne, is larger than the production TC rotor due to the large mass and moment of inertia of the oil-free TC rotor even though air has lower viscosity than the TC lubricant oil. Separate experiments of the oil-free TC installed on a diesel engine demonstrate the reliable dynamic forced performance and superior rotor dynamic stability of the oil-free TC over the oil-lubricated TC. The post on-engine test inspection of the oil-free TC test hardware reveals no evidence of significant surface wear between the rotor and bearings, as well as no dimensional changes in the rotor outer surfaces and bearing top foil inner surfaces. The present experimental characterization and verified robustness of the oil-free TC system continue to extend the GFB knowledge database.

scholarly journals Design and Performance Evaluation of a Very Low Flow Coefficient Centrifugal Compressor

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Yongsheng Wang ◽  
Feng Lin ◽  
Chaoqun Nie ◽  
Abraham Engeda
Keyword(s):  
Centrifugal Compressor ◽  
Cfd Simulation ◽  
Volume Flow Rate ◽  
Three Dimensional ◽  
Flow Coefficient ◽  
Low Flow ◽  
Centrifugal Compressors ◽  
Lower Efficiency ◽  
One Dimensional ◽  
Low Flow Coefficient

Very low flow coefficient centrifugal compressors are often applied as the last stages of multistage compressors. Due to the lower volume flow rate, the flow channels in the impeller and diffuser are so narrow that friction loss becomes the main factor, which leads to lower efficiency than that of other stages in the same compressors. In addition, most of design methods are generally based on medium flow coefficient centrifugal compressors. Taking on researches on the low flow coefficient centrifugal compressors is significant and necessary. One-dimensional (1D) code, consisting of design and analysis parts, is developed in this study to provide basic geometric data and predict the entire performance of centrifugal compressor. Three-dimensional geometry of the impeller is built. CFD simulation is carried out as well to be compared with 1D prediction. With the continuous geometry adjustment, the final performance of the centrifugal compressor will be fixed once the performance discrepancy between CFD and one-dimensional code is acceptable. The details on the flow field within impeller will be presented through CFD.

Performance of Inward Radial Flow Turbines under Steady Flow Conditions with Special Reference to High Pressure Ratios and Partial Admission

1969 ◽  
Vol 184 (1) ◽  
pp. 1027-1042 ◽  
Author(s):  
F. J. Wallace ◽  
P. R. Cave ◽  
J. Miles
Keyword(s):  
High Speed ◽  
Radial Flow ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Design Tool ◽  
Experimental Results ◽  
Performance Measurements ◽  
One Dimensional ◽  
Partial Admission ◽  
The One

The paper describes an extension of an earlier and very successful one-dimensional analysis by one of the authors (reference (1)) for design and off-design performance evaluation of inward radial flow turbines to include four cases not covered by the earlier analysis: high overall pressure ratios leading to either nozzle or rotor choking; partial admission; variable nozzle angle; allowance for nozzle and rotor loss coefficients (references (2) and (3)). Each of these extensions of the original theory has been programmed in FORTRAN. The full admission results are compared with performance measurements obtained on a C.A.V. type 01 turbine in conjunction with a specially designed high-speed dynamometer for pressure ratios up to 1.6, the analysis being extended to a maximum value of 4.0. The partial admission results are compared with experimental results reported in reference (4). The variable nozzle angle results are given as an example of the flexibility of the method. Finally, the loss coefficient treatment of Benson (reference (2)) which was based on reference (1) in conjunction with experimental results reported in reference (5), is applied to the full admission tests of the present paper. The object of the paper is to give a comprehensive account of the power of the one-dimensional treatment as a design tool, with the inference that two-and three-dimensional treatments (references (6)-(9)) are basically more suitable for detailed flow analysis rather than basic design.

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