Numerically Derived Design Guidelines of Self Recirculation Casing Treatment for Industrial Centrifugal Compressors

2016 ◽  
Author(s):  
Sewoong Jung ◽  
Robert Pelton
Keyword(s):  
Fluid Dynamic ◽  
Cost Effective ◽  
High Volume ◽  
Design Guidelines ◽  
Slot Width ◽  
Optimized Design ◽  
Centrifugal Compressors ◽  
Casing Treatment ◽  
High Volume Production ◽  
Derived Design

Casing treatments are a well-known method to extend operating range of centrifugal compressors. A common casing treatment configuration consists of a passage that allows flow from the impeller shroud to be bleed back to the inlet of the stage. This type of casing treatment is used frequently in some applications, including automotive turbochargers, but is rarely used in industrial compressors. An effective casing treatment must be developed specifically to match a given stage. For high volume production products this is practical. For the wide variety of industrial compressor designs, which are produced in low volumes, it is not often cost effective to design a casing treatment to match each application. To help reduce the design effort associated with developing a new casing treatment design, a simple set of design guidelines were developed. These guidelines are based on the results of a computational fluid dynamic (CFD) study of several different class impellers. These guidelines can be used to correctly locate and size the key geometric features of a self-recirculating casing treatment, including slot width, position and cavity vane profile. The study found that the bleed slot position and width were the primary factors controlling performance of the casing treatment. In general, when the slot width is wider and the bleed position is moved further downstream, the range increases but the efficiency falls. The optimal slot width is found to be when the slot area is 23% of the area of inducer eye and positioning the slot near the impeller throat gives a good balance of increased range with minimal efficiency loss. A well designed casing treatment is expected to result in approximately a 25% increase in range while keeping the drop in efficiency less than 0.4 point for the cases considered in this study. In addition, the rise to surge increased more than 60% and turndown almost doubled value with the optimized design.

PROCESS INDEPENDENT MACHINING SIMULATION — A BAR TURNING APPROACH

2007 ◽  
Vol 06 (01) ◽  
pp. 5-19 ◽  
Author(s):  
EYSION A. LIU ◽  
YIQING YUAN ◽  
JAMES D. HILL ◽  
QIAN ZOU
Keyword(s):  
Manufacturing Industry ◽  
Metal Cutting ◽  
Cost Effective ◽  
High Volume ◽  
Machining Process ◽  
Machining Processes ◽  
High Volume Production ◽  
Manufacturing Productivity ◽  
Bar Turning ◽  
Force Calculation

Computer simulation of industrial processes is an important alternative that may be used either to complement or to replace expensive experimental procedures associated with developing new parts or modifying existing process. For a metal cutting process, numerical simulations provide vital information about cutting forces, cutting temperatures, tooling and part distortion, etc. Since the early 1970s, FEA has been applied to simulate machining process. The development of this approach, its assumptions and techniques has been widely accepted. Nowadays, the manufacturing productivity even drives the community to the next level innovation through computer utilizations. A kinematic simulation of machining processes is one of many innovative CAE applications, especially beneficial to high volume production of automotive powertrain parts. In this paper, a generic force calculation method is introduced with a modified horsepower correction factor. An example of sizing milling force, milling paths and proper milling parameters is provided by utilizing the methodology. This paper will also discuss and propose how the manufacturing industry uses this resourceful tool. Applications of the methodology would empower product and manufacturing engineers to make intelligent and cost effective decisions.

Cost-Effective Single Step Cofiring Process for Manufacturing Solid Oxide Fuel Cells Using HSC™ Anode

2010 ◽  
Vol 7 (2) ◽  
Author(s):  
Kyung Joong Yoon ◽  
Guosheng Ye ◽  
Srikanth Gopalan ◽  
Uday B. Pal
Keyword(s):  
Active Layer ◽  
Low Cost ◽  
Cost Effective ◽  
High Volume ◽  
Single Step ◽  
Solid Oxide ◽  
Fine Grained ◽  
High Volume Production ◽  
Volume Production ◽  
Anode Substrate

The anode-supported planar solid oxide fuel cell (SOFC) was fabricated by a cost-effective single step cofiring process using high shear compaction (HSC)™ anode substrate. The HSC™ process is a novel ceramic tape fabrication technique, which offers advantages in low-cost and high-volume production of the anode substrates over the conventional tape forming processes. The cell was comprised of a porous HSC™ Ni+8 mol % yttria-stabilized zirconia (YSZ) anode substrate, a porous Ni+YSZ anode barrier layer, a porous and fine-grained Ni+YSZ anode active layer, a dense YSZ electrolyte, a porous and fine-grained Ca-doped LaMnO3(LCM)+YSZ composite cathode active layer, and a porous LCM cathode current collector layer. The fabrication process involved wet powder spraying of the anode barrier layer over the HSC™ anode substrate followed by screen-printing of the remaining component layers. The cell was then cofired at 1340°C for 2 h. The microstructure and the open circuit voltage of the cell confirmed that the cell was crack-free and leak-tight. The cofired cell showed a stable and acceptable electrochemical performance at 800°C under humidified hydrogen (3–60% H2O) as fuel and air as oxidant. The anode active layer with finer and less porous microstructure increased the triple phase boundary length and improved cell performance under conditions that simulated higher fuel utilization. The material system and fabrication process presented in this work offers great advantage in low-cost and high-volume production of SOFCs, and it can be the basis for scale-up and successful commercialization of the SOFC technology.

scholarly journals Design and Implementation of 64-bit SRAM and CAM on Cadence and Open-source environment

2021 ◽  
Vol 15 ◽  
pp. 586-594
Author(s):  
N. Shylashree ◽  
Yatish D. Vahvale ◽  
N. Praveena ◽  
A. S. Mamatha
Keyword(s):  
Open Source ◽  
Random Access ◽  
Cost Effective ◽  
High Volume ◽  
Memory Devices ◽  
Content Addressable Memory ◽  
Sram Cell ◽  
Timing Data ◽  
Main Motive ◽  
High Volume Production

Low-power IC design has become a priority in recent years because of the growing proliferation of portable battery-operated devices, bringing Static Random-Access Memory (SRAM) and Content Addressable Memory (CAM) into play. In today's SoCs, embedded SRAM units have become a necessary component. There is a lack of chips in the current world and to manufacture chips there is the requirement of Electronic Design Automation(EDA) tools that can perform better. In this paper, the main motive is to showcase the performance of open-source tools available currently which can still generate the required output with no cost. In this new era of fast mobile computing, traditional SRAM cell designs are power-demanding and underperforming. Rather than lowering manufacturing costs through high-volume production, specialty memory give cost-effective alternatives through architecture. Specialty memory devices enable the designer to address issues like board area, important timing, data flow bottlenecks, and so on in ways that high-volume regular memory devices cannot. Implementation of memory devices on Cadence environment and open-source environment to check the compatibility and compare the power, area, and delay of both 64-bit SRAM and CAM also analysing and validating the results of both the memory devices in this paper. For SRAM in a cadence environment, the calculated power, area, and slack have improved values, namely 0.145mW, 1104.3um2, and positive slack of 6636. Furthermore, the power for 64-bit CAM in a cadence context is nearly identical to those for an open-source environment ~0.8mW. In an open-source environment, the calculated slack for CAM is 4.74.

Towards a Manufacturing Technology for High-Volume Production of Composite Components

1992 ◽  
Vol 206 (2) ◽  
pp. 77-91 ◽  
Author(s):  
C D Rudd ◽  
K N Kendall
Keyword(s):  
Cost Effective ◽  
High Volume ◽  
Process Technology ◽  
Reinforced Composite ◽  
High Volume Production ◽  
Volume Production ◽  
The University ◽  
Design And Manufacture ◽  
Transfer Moulding ◽  
The Relationship

The last decade has seen strong interest from high-volume manufacturers such as the automotive industry in the development of processes which provide cost effective routes to the manufacture of components in fibre-reinforced composite materials. This paper considers one family of processes that have been targeted as offering a solution—that of resin transfer moulding (RTM)—and reviews the findings of work based at the University of Nottingham. The mechanisms involved are examined together with the variants on the basic process and the implications for high-volume production. Consideration is given to process technology, materials and the relationship between design and manufacture. A route to high-volume manufacture based upon computer aided engineering is proposed.

Casing Treatment and Inlet Swirl of Centrifugal Compressors

2012 ◽  
Author(s):  
Hua Chen ◽  
Vai-Man Lei
Keyword(s):  
Cost Effective ◽  
Centrifugal Compressors ◽  
Suction Surface ◽  
Blade Loading ◽  
Casing Treatment ◽  
Wall Boundary Layer ◽  
Flow Swirl ◽  
Flow Loss ◽  
Layer Region ◽  
Ported Shroud

Ported shroud is a cost effective casing treatment that can greatly improve stability of centrifugal compressors. It is widely used in turbochargers and other applications where compressors with wide flow range are required. This paper reviews the development of the ported shroud concept from its first conception in the 1980s to its current various configurations, explores the underline mechanisms that deliver the performance improvement. It is explained that by removing stagnant fluid from impeller inducer shroud end wall boundary-layer region and recirculating it to the impeller inlet, blade loading near the inducer shroud is increased with improved inlet suction. For transonic flow, ported shroud weakens the shock wave and reduces flow separation on the inducer suction surface. It is argued that the effectiveness of the ported shroud is a balance of blade loading and the flow loss inside the ported shroud cavity. The loss needs to be minimised if ported shroud is to be more effective. Blade loading may be increased by various methods such as using high inducer blade turning and using full bladed impellers. The blade loading can also be improved by removing flow swirl in ported shroud flow by vanes, or imposing negative swirl by vanes in ported shroud. Circumferential flow variation caused by volute housing can be taken into account by variable pitch vanes or by variable port position.

Casing Treatment and Inlet Swirl of Centrifugal Compressors

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Hua Chen ◽  
Vai-Man Lei
Keyword(s):  
Cost Effective ◽  
Centrifugal Compressors ◽  
Suction Surface ◽  
Blade Loading ◽  
Casing Treatment ◽  
Wall Boundary Layer ◽  
Flow Swirl ◽  
Flow Loss ◽  
Layer Region ◽  
Ported Shroud

Ported shroud is a cost-effective casing treatment that can greatly improve stability of centrifugal compressors. It is widely used in turbochargers and other applications where compressors with a wide flow range are required. This paper reviews the development of the ported shroud concept from its first conception in the 1980 s to its current various configurations and explores the underline mechanisms that deliver the performance improvement. It is explained that, by removing stagnant fluid from impeller inducer shroud end wall boundary-layer region and recirculating it to the impeller inlet, blade loading near the inducer shroud is increased with improved inlet suction. For transonic flow, the ported shroud weakens the shock wave and reduces flow separation on the inducer suction surface. It is argued that the effectiveness of ported shroud is a balance of blade loading and the flow loss inside the ported shroud cavity. The loss needs to be minimized if ported shroud is to be more effective. Blade loading may be increased by various methods, such as using high inducer blade turning and using full-bladed impellers. The blade loading can also be improved by removing flow swirl in ported shroud flow by vanes or imposing negative swirl by vanes in ported shroud. Circumferential flow variation caused by volute housing can be taken into account by variable pitch vanes or by variable port position.

Fracture-Tolerant and Shear-Resistant Interlayers for Mitigation of Reflective Cracking

2019 ◽  
Vol 2673 (10) ◽  
pp. 35-46
Author(s):  
Cristian Cocconcelli ◽  
Bongsuk Park ◽  
Jian Zou ◽  
George Lopp ◽  
Reynaldo Roque
Keyword(s):  
Asphalt Pavement ◽  
Aggregate Size ◽  
Cost Effective ◽  
Design Guidelines ◽  
Reflective Cracking ◽  
Rubber Membrane ◽  
Near Surface ◽  
Field Evidence ◽  
Cracking Performance ◽  
Interface Cracking

Reflective cracking is frequently reported as the most common distress affecting resurfaced pavements. An asphalt rubber membrane interlayer (ARMI) approach has been traditionally used in Florida to mitigate reflective cracking. However, recent field evidence has raised doubts about the effectiveness of the ARMI when placed near the surface, indicating questionable benefits to reflective cracking and increased instability rutting potential. The main purpose of this research was to develop guidelines for an effective alternative to the ARMI for mitigation of near-surface reflective cracking in overlays on asphalt pavement. Fourteen interlayer mixtures, covering three aggregate types widely used in Florida, and two nominal maximum aggregate sizes (NMAS) were designed according to key characteristics identified for mitigation of reflective cracking, that is, sufficient gradation coarseness and high asphalt content. The dominant aggregate size range—interstitial component (DASR-IC) model was used for the design of all mixture gradations. A composite specimen interface cracking (CSIC) test was employed to evaluate reflective cracking performance of interlayer systems. In addition, asphalt pavement analyzer (APA) tests were performed to determine whether the interlayer mixtures had sufficient rutting resistance. The results indicated that interlayer mixtures designed with lower compaction effort, reduced design air voids, and coarser gradation led to more cost-effective fracture-tolerant and shear-resistant (FTSR) interlayers. Therefore, preliminary design guidelines including minimum effective film thickness and maximum DASR porosity requirements were proposed for 9.5-mm NMAS (35 µm and 50%) and 4.75-mm NMAS FTSR mixtures (20 µm and 60%) to mitigate near-surface reflective cracking.

scholarly journals Congener-specific partition properties of chlorinated paraffins evaluated with COSMOtherm and gas chromatographic retention indices

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jort Hammer ◽  
Hidenori Matsukami ◽  
Satoshi Endo
Keyword(s):  
Chemical Properties ◽  
High Volume ◽  
Retention Indices ◽  
Chromatographic Retention ◽  
Linear Free Energy Relationship ◽  
Linear Free Energy ◽  
Chlorinated Paraffins ◽  
Gas Chromatographic Retention Indices ◽  
High Volume Production ◽  
Volume Production

AbstractChlorinated Paraffins (CPs) are high volume production chemicals and have been found in various organisms including humans and in environmental samples from remote regions. It is thus of great importance to understand the physical–chemical properties of CPs. In this study, gas chromatographic (GC) retention indexes (RIs) of 25 CP congeners were measured on various polar and nonpolar columns to investigate the relationships between the molecular structure and the partition properties. Retention measurements show that analytical standards of individual CPs often contain several stereoisomers. RI values show that chlorination pattern have a large influence on the polarity of CPs. Single Cl substitutions (–CHCl–, –CH2Cl) generally increase polarity of CPs. However, many consecutive –CHCl– units (e.g., 1,2,3,4,5,6-C11Cl6) increase polarity less than expected from the total number of –CHCl– units. Polyparameter linear free energy relationship descriptors show that polarity difference between CP congeners can be explained by the H-bond donating properties of CPs. RI values of CP congeners were predicted using the quantum chemically based prediction tool COSMOthermX. Predicted RI values correlate well with the experimental data (R2, 0.975–0.995), indicating that COSMOthermX can be used to accurately predict the retention of CP congeners on GC columns.

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