Axial Cascade Technology and Application to Flow Path Designs. Part II—Application of Data to Flow Path Designs

1968 ◽  
Vol 90 (4) ◽  
pp. 329-340
Author(s):  
O. E. Balje´
Keyword(s):  
Calculated Data ◽  
Flow Path ◽  
Fair Agreement ◽  
Design Parameters ◽  
Performance Potential ◽  
Test Information ◽  
Speed Regime ◽  
Specific Speed

The cascade considerations presented in Part I are extended to obtain interrelations between cascade parameters and machine similarity parameters, and to assess the effect of compressibility on these interrelations. These data are used to compute the efficiency potential and cavitation sensitivity of single cascaded and multiple cascaded axial machines in the medium to high specific speed regime. The calculated data show fair agreement with the available test information. The effect of only a limited number of design parameters has been investigated. Further studies will be required to cover the performance potential adequately.

Loss and Flow Path Studies on Centrifugal Compressors—Part I

1970 ◽  
Vol 92 (3) ◽  
pp. 275-286 ◽  
Author(s):  
O. E. Balje´
Keyword(s):  
Boundary Layer ◽  
Flow Separation ◽  
Calculated Data ◽  
Flow Path ◽  
Fair Agreement ◽  
Pressure Gradients ◽  
Momentum Thickness ◽  
Centrifugal Compressors ◽  
Separation Criterion ◽  
Test Information

Relations are derived for the boundary layer momentum thickness growth in channels with adverse pressure gradients and for the maximum allowable momentum thickness to avoid flow separation. These data are obtained by integrating the Truckenbrodt equation stepwise and by extending the Gruschwitz-Schmidbauer separation criterion. Fair agreement between calculated data and test information is demonstrated.

Robust Design Techniques for Evaluating Fuel Cell Thermal Performance

2006 ◽  
Author(s):  
Kenneth J. Kelly ◽  
Gregory C. Pacifico ◽  
Michael Penev ◽  
Andreas Vlahinos
Keyword(s):  
Fuel Cell ◽  
Heat Generation ◽  
Thermal Performance ◽  
Gas Flow ◽  
Internal Heat ◽  
Flow Path ◽  
Coolant Flow ◽  
Design Parameters ◽  
Fuel Cell Stack ◽  
Path Design

The National Renewable Energy Laboratory (NREL) and Plug Power Inc. have been working together to develop fuel cell modeling processes to rapidly assess critical design parameters and evaluate the effects of variation on performance. This paper describes a methodology for investigating key design parameters affecting the thermal performance of a high temperature, polybenzimidazole (PBI)-based fuel cell stack. Nonuniform temperature distributions within the fuel cell stack may cause degraded performance, induce thermo-mechanical stresses, and be a source of reduced stack durability. The three-dimensional (3-D) model developed for this project includes coupled thermal/flow finite element analysis (FEA) of a multi-cell stack integrated with an electrochemical model to determine internal heat generation rates. Sensitivity and optimization algorithms were used to examine the design and derive the best choice of the design parameters. Initial results showed how classic design-of-experiment (DOE) techniques integrated with the model were used to define a response surface and perform sensitivity studies on heat generation rates, fluid flow, bipolar plate channel geometry, fluid properties, and plate thermal material properties. Probabilistic design methods were used to assess the robustness of the design in response to variations in load conditions. The thermal model was also used to develop an alternative coolant flow-path design that yields improved thermal performance. Results from this analysis were recently incorporated into the latest Plug Power coolant flow-path design. This paper presents an evaluation of the effect of variation on key design parameters such as coolant and gas flow rates and addresses uncertainty in material thermal properties.

Vibration-Based Early Crack Diagnosis With Machine Learning for Spur Gears

2020 ◽  
Author(s):  
Fatih Karpat ◽  
Ahmet Emir Dirik ◽  
Onur Can Kalay ◽  
Oğuz Doğan ◽  
Burak Korcuklu
Keyword(s):  
Machine Learning ◽  
Fault Diagnosis ◽  
High Speed ◽  
Crack Detection ◽  
Power Transmission ◽  
Calculated Data ◽  
Design Parameters ◽  
Tooth Stiffness ◽  
Vibration Responses ◽  
Root Crack

Abstract Gear mechanisms are one of the most significant components of the power transmission systems. Due to increasing emphasis on the high-speed, longer working life, high torques, etc. cracks may be observed on the gear surface. Recently, Machine Learning (ML) algorithms have started to be used frequently in fault diagnosis with developing technology. The aim of this study is to determine the gear root crack and its degree with vibration-based diagnostics approach using ML algorithms. To perform early crack detection, the single tooth stiffness and the mesh stiffness calculated via ANSYS for both healthy and faulty (25-50-75-100%) teeth. The calculated data transferred to the 6-DOF dynamic model of a one-stage gearbox, and vibration responses was collected. The data gathered for healthy and faulty cases were evaluated for the feature extraction with five statistical indicators. Besides, white Gaussian noise was added to the data obtained from the 6-DOF model, and it was aimed at early fault diagnosis and condition monitoring with ML algorithms. In this study, the gear root crack and its degree analyzed for both healthy and four different crack sizes (25%-50%-75%-100%) for the gear crack detection. Thereby, a method was presented for early fault diagnosis without the need for a big experimental dataset. The proposed vibration-based approach can eliminate the high test rig construction costs and can potentially be used for the evaluation of different working conditions and gear design parameters. Therefore, catastrophic failures can be prevented, and maintenance costs can be optimized by early crack detection.

scholarly journals CFD computation of flow in the flow path of a torque flow pump

2020 ◽  
Vol 207 ◽  
pp. 04005
Author(s):  
Dmitry Svoboda ◽  
Igor Borshchev ◽  
Aleksandr Zharkovskii ◽  
Evgeniy Tvanov ◽  
Arsentiy Klyuyev
Keyword(s):  
Fluid Flow ◽  
Flow Visualization ◽  
Experimental Research ◽  
Flow Path ◽  
Sufficient Accuracy ◽  
Work Process ◽  
Energy Characteristics ◽  
Specific Speed ◽  
3D Methods ◽  
Flow Pump

The results are presented of numerical and experimental research of fluid flow in the flow path of a torque flow pump with specific speed ns ;: 55. The 3D methods of CFD have been shown to allow for predicting energy characteristics of this type of pumps with a sufficient accuracy. According to the results of flow visualization the work process has been analysed and conclusions drawn to enhance TFP efficiency.

A Meridian Profile Obtained by No Restriction in Optimum Process

2015 ◽  
Author(s):  
Takuji Tsugawa
Keyword(s):  
Rotational Speed ◽  
Guide Vane ◽  
Friction Loss ◽  
Design Parameters ◽  
Optimum Process ◽  
Blade Number ◽  
Impeller Outlet ◽  
Normal Diameter ◽  
Specific Speed

In previous study of optimum meridian profile of impeller and guide-vane, almost all design parameters included in the specific speed and blade number are variable design parameters in optimum process. As the result, optimum specific speed and blade number were obtained. In the calculation, loss calculation consists of blade-to-blade diffusion loss and axial-symmetrical annular wall friction loss. The calculation result without annular friction loss head isn’t affected by normal diameter and rotational speed. In consideration of diffusion loss and annular friction loss, the result of calculation is affected by normal diameter and rotational speed. In this case study, normal diameter and rotational speed are also variable design parameters. The normal diameter is mid span impeller outlet diameter. So, normal velocity is peripheral velocity of mid span impeller outlet. The initial normal diameter is 100mm and the initial rotational speed is 1000min−1. And then, design parameters and all specification become variable. As there isn’t constant design parameter in this case study, there is no restriction in optimum process. As there is no restriction in optimum process, the best one optimum meridian profile can be obtained. In one case, the object function contains the efficiency and suction specific speed. In the other case, the object function contains the only efficiency. As the result, the optimum meridian profile of impeller and guide-vane can be obtained in each case.

Influence of the Different Design Parameters to the Centrifugal Compressor Tip Clearance Loss

2011 ◽  
Author(s):  
Teemu Turunen-Saaresti ◽  
Ahti Jaatinen
Keyword(s):  
Centrifugal Compressor ◽  
Tip Clearance ◽  
Design Parameters ◽  
Clear Correlation ◽  
Compressor Stage ◽  
Centrifugal Compressors ◽  
Blade Number ◽  
Overall Performance ◽  
Specific Speed

In this paper the effect of the tip clearance was studied with six different centrifugal compressors and data available in literature. The changes in the overall performance of the compressor stage were examined. The aim was to study the influence of the different design parameters to the tip clearance loss. It was evident by the previous studies that the sensitivity of the centrifugal compressor to the tip clearance loss varies with different designs. However, for the designer it is important to know the effect of the tip clearance loss in order to initially evaluate the quality of different designs. Analysis of the data demonstrated that no clear correlation between the sensitivity of the tip clearance loss and the specific speed, the diffusion ratio, the blade number and the ratio of blade heights exists.

Evaluation of Blade Passage Analysis Using Coarse Grids

2000 ◽  
Vol 122 (2) ◽  
pp. 345-348 ◽  
Author(s):  
Steven M. Miner
Keyword(s):  
Rotational Speed ◽  
Stokes Equations ◽  
Axial Flow ◽  
Measured Data ◽  
Flow Coefficient ◽  
Design Parameters ◽  
Mixed Flow ◽  
Specific Speed ◽  
Coarse Grids ◽  
Flow Pump

This paper presents the results of a study using coarse grids to analyze the flow in the impellers of an axial flow pump and a mixed flow pump. A commercial CFD code (FLOTRAN) is used to solve the 3-D Reynolds Averaged Navier Stokes equations in a rotating cylindrical coordinate system. The standard k−ε turbulence model is used. The meshes for this study use 22,000 nodes and 40,000 nodes for the axial flow impeller, and 26,000 nodes for the mixed flow impeller. Both models are run on a SPARCstation 20. This is in contrast to typical analyses using in excess of 100,000 nodes. The smaller mesh size has advantages in the design environment. Stage design parameters for the axial flow impeller are, rotational speed 870 rpm, flow coefficient ϕ=0.13, head coefficient ψ=0.06, and specific speed 2.97 (8101 US). For the mixed flow impeller the parameters are, rotational speed 890 rpm, flow coefficient ϕ=0.116, head coefficient ψ=0.094, and specific speed 2.01 (5475 US). Evaluation of the models is based on a comparison of circumferentially averaged results to measured data for the same impeller. Comparisons to measured data include axial and tangential velocities, static pressure, and total pressure. A comparison between the coarse and fine meshes for the axial flow impeller is included. Results of this study show that the computational results closely match the shapes and magnitudes of the measured profiles, indicating that coarse CFD models can be used to accurately predict performance. [S0098-2202(00)02202-1]

scholarly journals The Efficiencies of Single-Stage Centrifugal Compressors for Aircraft Applications

1991 ◽  
Author(s):  
C. Rodgers
Keyword(s):  
Mach Number ◽  
State Of The Art ◽  
Single Stage ◽  
Critical Parameters ◽  
Design Parameters ◽  
Centrifugal Compressors ◽  
Design Work ◽  
Engine Design ◽  
Specific Speed ◽  
System Power

The thrust of most recent advances in single– and two–stage centrifugal compressor technology by the aerospace community has been motivated by interest in increasing airbreathing propulsion system power density, and improving specific fuel consumption with higher stage pressure ratios. Advances in the last decade have made it appropriate to review the major design parameters influencing the efficiency levels of single–stage centrifugal compressors for aircraft applications. A simple efficiency correlation was derived for advanced single–stage centrifugal compressors. It was based upon four critical parameters: • Inlet Specific Speed • Impeller Tip Diameter • Inducer Tip Relative Mach Number • Exit Discharge Mach Number The correlation was shown to predict attainable state–of–the–art efficiencies within a band width of ± 2 % points. This was considered acceptable for preliminary compressor and engine design work.

Case Study of High Specific Speed Radial Impeller

2002 ◽  
Author(s):  
Takuji Tsugawa
Keyword(s):  
Radial Flow ◽  
Velocity Ratio ◽  
Axial Flow ◽  
Optimum Shape ◽  
Design Parameters ◽  
Shape Factors ◽  
Flow Angle ◽  
Diffusion Factor ◽  
Cavitation Performance ◽  
Specific Speed

The optimum shape of high specific speed impeller is usually axial flow impeller. The radial impeller is often used without axial flow guidevane. Usually, the radial impeller is the high pressure and low specific speed impeller. The design parameters of radial high specific speed impeller have not been obtained yet. In the previous papers, the optimum meridian shape of axial flow impeller with axial flow guidevane is obtained for various specific speed. The optimum meridian shapes calculated by diffusion factor agree with meridian shapes of conventional impellers. In this paper, the design parameters of radial high specific speed impellers without guidevane are calculated by diffusion factor. And the optimum meridian shapes of radial high specific speed impellers are proposed. In case of the radial impeller, the hub diameter is equal to the tip diameter in impeller outlet. So, in radial impellers, the outlet hub-tip ratio is 1.0. The optimum meridian shapes of radial impellers for various specific speed are also obtained in this paper. The relative efficiency and cavitation performance of impellers in various shape factors were calculated. The calculation of radial meridian shape needs four kinds of shape factors as the previous papers. The four shape factors are inlet relative flow angle β1, turning angle Δβ, axial velocity ratio (meridian velocity ratio) kc = Cm2/Cm1 and impeller diameter ratio kd = D1c/D2c inmid span streamsurface. In initial step of impeller design, the result of the efficiency and cavitation performance of impeller calculated in optimum principal design parameters is important. The principal design parameters are hub-tip ratio, inlet-outlet diameter ratio, axial velocity ratio, solidity, inlet flow angle, turning angle and blade number. The author proposed the optimum meridian profile design method by diffusion factor for various condition of design parameters. There is a good correlation between the optimum hub-tip ratio and the specific speed considering cavitation performance. The optimum solidity is obtained for the specific speed considering efficiency and cavitation performance. It was found that the optimum meridian profile of high specific speed impeller with appropriate efficiency and cavitation performance has large inclination on hub and tip stream lines. The calculated data base is four dimensional using four various shape parameter β1, Δβ, kc and kd. Using the four shape factor, the optimum meridian shape of radial flow impeller is able to be obtained. The best 1000 optimum design parameters are selected using four dimensional calculated data. The aspect of optimization is recognized with 1000 plotted data on 6 planes. The result of radial flow impeller optimization is different from that of axial flow impeller. In case of axial flow impellers, the shape factors are optimized for each specific speed. But, in radial flow impellers, if both the specific speed and the total head coefficient are given, the optimum shape factors are optimized. The calculation results between profiles and specifications were very useful for the development of new type high specific speed radial impellers.

scholarly journals A device for reducing the siltation of the front chamber of the pumping station in irrigation systems

2021 ◽  
Vol 274 ◽  
pp. 03001
Author(s):  
Boborakhim Urishev ◽  
Sobir Eshev ◽  
Fakhriddin Nosirov ◽  
Ulugbek Kuvatov
Keyword(s):  
Hydraulic Structure ◽  
Experimental Studies ◽  
Calculated Data ◽  
Bottom Layer ◽  
Design Parameters ◽  
Pipeline System ◽  
New Device ◽  
Water Jets ◽  
Pumping Stations ◽  
Calculation Methodology

It has been determined that the reduction of siltation of the front chamber is necessary because the deposited sediments seriously violate the planned hydraulic structure of the flow when water is sucked up by pumps, as a result of which their efficiency decreases. The method of calculating the pipeline system of a new device designed to significantly reduce the siltation of the front chamber of irrigation pumping stations by artificially creating turbulence in the water flow in the bottom layer of the structure is presented. This calculation methodology is based on the use of the theory of flooded water jets, which makes it possible to determine the main characteristics of the jet. The latter allows calculating the design parameters of the pipeline system. The results of experimental studies are presented to compare the calculated data with the results of experiments, as well as to determine the effectiveness of the proposed device for a significant reduction in siltation of the front chamber of irrigation pumping stations.

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