Influence of pressure distribution in the gap of piston-cylinder unit and properties of working fluid PES-3 on characteristics of high pressure piston-cylinder unit

2020 ◽  
pp. 38-42
Author(s):  
A. E. Aslanyan
Keyword(s):  
Mathematical Model ◽  
High Pressure ◽  
Pressure Distribution ◽  
Pressure Range ◽  
Pressure Change ◽  
Working Fluid ◽  
Research Results ◽  
Piston Cylinder ◽  
Pressure Distributions ◽  
The Mathematical Model

A simulation of the use of PES-3 liquid in a high-pressure piston-cylinder units was performed, and the parameters of the piston-cylinder units were determined in the article. The equations of the mathematical model describing the pressure change in the gap between the piston and the cylinder are given. As a result of the calculations, the pressure distributions in the gap between the piston and the cylinder are determined at under piston pressures less than 1.6 GPa. The profiles of the gaps between the deformed piston and cylinder at different under piston pressures are calculated. The dependences of the speed of lowering the piston and the effective gap on the under piston pressure at different gaps of the undeformed piston-cylinder unit are obtained. The research results can be used in the design of piston cylinder units operating on PES-3 liquid in the pressure range of 0.01–1.6 GPa.

Multi-Object Multi-Discipline Probabilistic Design of High-Pressure Turbine Blade-Tip Radial Running Clearance

2013 ◽  
Vol 572 ◽  
pp. 551-554
Author(s):  
Wen Zhong Tang ◽  
Cheng Wei Fei ◽  
Guang Chen Bai
Keyword(s):  
Mathematical Model ◽  
High Pressure ◽  
Optimal Design ◽  
Mechanical System ◽  
High Accuracy ◽  
Probabilistic Design ◽  
High Pressure Turbine ◽  
Surface Method ◽  
Blade Tip ◽  
The Mathematical Model

For the probabilistic design of high-pressure turbine (HPT) blade-tip radial running clearance (BTRRC), a distributed collaborative response surface method (DCRSM) was proposed, and the mathematical model of DCRSM was established. From the BTRRC probabilistic design based on DCRSM, the static clearance δ=1.865 mm is demonstrated to be optimal for the BTRRC design considering aeroengine reliability and efficiency. Meanwhile, DCRSM is proved to be of high accuracy and efficiency in the BTRRC probabilistic design. The present study offers an effective way for HPT BTRRC dynamic probabilistic design and provides also a promising method for the further probabilistic optimal design of complex mechanical system.

Research on Sealing Performance in High Pressure Oil-Free Miniature Air Compressor

2017 ◽  
Author(s):  
Yipan Deng ◽  
Yinshui Liu ◽  
Fan Li ◽  
Pengyun Tian ◽  
Na Miao
Keyword(s):  
Mathematical Model ◽  
High Pressure ◽  
Pressure Distribution ◽  
Research Work ◽  
Piston Rings ◽  
Premature Failure ◽  
Air Compressor ◽  
Sealing Performance ◽  
Rotary Speed ◽  
Discharge Pressure

High pressure oil-free miniature air compressor has an irreplaceable role in some high demand areas such as cooling, scuba diving and pneumatic catapult due to its remarkable advantages such as compacted size, lightened weight and clean output gas. As the important sealing component in the high pressure oil-free miniature air compressor, piston rings hold the properties such as tiny diameter (less than 10mm), high sealing pressure (up to 410 bar) and high surrounding temperature (up to 500K), which make them distinctive from conventional piston rings. A mathematical model was established to simulate the pressure distribution of the compressor chamber, as well as the gap between the sealing rings. Sensitive parameters were considered to investigate their effects on the sealing performance such as the number and the cut size of the piston rings, the suction and discharge pressure and the rotary speed. The mathematical model was verified by comparing to published experimental research work. These work help to reveal the severe non-uniformity of the pressure distribution of different chambers, which were suggested be the primary cause of the premature failure of the sealing rings, thus improving the sealing performance and the service life of the air compressor.

Performance Analysis of a Solar-Assisted Organic Rankine Cycle

2020 ◽  
Author(s):  
M. T. Nitsas ◽  
I. P. Koronaki
Keyword(s):  
Mathematical Model ◽  
Performance Analysis ◽  
Temporal Variation ◽  
Storage Tank ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Evaporation Temperature ◽  
Solar Powered ◽  
The Mathematical Model

Abstract The objective of this paper is the thermodynamic analysis of a solar powered Organic Rankine Cycle (O.R.C.) and the investigation of potential working fluids in order to select the optimum one. A dynamic model for a solar O.R.C. with a storage tank, which produces electricity is developed. The mathematical model includes all the equations that describe the operation of the solar collectors, the storage tank, the Rankine Cycle and the feedback between them. The model runs for representative days throughout the year, calculating the net produced energy as a function of the selected evaporation temperature for every suitable working fluid. Above that, the temporal variation of the systems’ temperatures, collectors’ efficiency and net produced power, for the optimum organic fluid and evaporation temperature are presented.

A Mathematical Calculation Method for Hysteresis Characteristics Analysis of Arc-Shaped Finger Seal

2020 ◽  
Author(s):  
Chun-Hua Du ◽  
Yan-Chao Zhang ◽  
Ya-Hui Cui ◽  
Shu-Na Dong ◽  
Hong-Hu Ji ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Structural Parameters ◽  
Maximum Error ◽  
Calculation Model ◽  
Correction Coefficient ◽  
Research Results ◽  
Characteristics Analysis ◽  
Leakage Characteristics ◽  
The Mathematical Model ◽  
Hysteresis Characteristics

Abstract In order to accurately predict the hysteresis characteristics of finger seal, the minimum hysteresis which can directly reflect the hysteresis of finger seal is proposed to characterize the hysteresis of finger seal. The mathematical model for calculating the minimum hysteresis of finger seal is established, the correction coefficient in the mathematical model is determined, and the mathematical model is verified by experiments. The influence of the structure and working condition parameters of finger laminates on the hysteresis characteristics is studied based on the modified calculation model, and the rule of influence is obtained in the end. Research results show that the maximum error between the leakage characteristics numerical calculation of finger seal base on modified calculation model and the experiment results is 7.64%, and the mathematical model of the minimum hysteresis is reasonable and reliable. The descending order of influence degree of structural parameters on the hysteresis characteristics of finger seal is: thickness of each finger laminate, finger repeat angle, arc radius of the finger beam arcs‘ centers, diameter of the finger base circle, width of the interstice between fingers, arc radius of finger beam. The research results provide a theoretical basis for further research on the influence of hysteresis on the finger seal leakage characteristics and the optimal design of finger seal structure.

scholarly journals Review of existing and development of a novel mathematical model for supercritical CO2 cycles working fluid

2018 ◽  
Vol 240 ◽  
pp. 01036
Author(s):  
Marcin Wołowicz ◽  
Jarosław Milewski ◽  
Piotr Lis
Keyword(s):  
Experimental Data ◽  
Carbon Dioxide ◽  
Mathematical Model ◽  
Heat Capacity ◽  
Supercritical Co2 ◽  
Pressure Range ◽  
Critical Conditions ◽  
Working Fluid ◽  
Critical Properties ◽  
Area Of Interest

The paper aims to compare the models of working fluids against experimental data for carbon dioxide close to its critical conditions. Fortunately, most of the work is already done and published where the authors compared the models based on the equation of the state (EoS). There are a few other models which were not investigated, thus we would like to add a few new results here and focus only on near-critical properties where the biggest deviation between experimental and calculated properties can be observed. The area of interest was pressure range of 7.39 – 20 MPa and temperature range of 304-340 K just above fluid critical point (7.39 MPa, 304.25 K). Model validation was performed for density and heat capacity as one of the most important parameters in preliminary cycle analysis.

Micro Surface Shaping for the High-Pressure Operation of Piston Machines With Water as a Working Fluid

2015 ◽  
Author(s):  
Meike H. Ernst ◽  
Monika Ivantysynova
Keyword(s):  
High Pressure ◽  
High Pressures ◽  
Working Fluid ◽  
Hydraulic Systems ◽  
Machinery Construction ◽  
Pressure Buildup ◽  
Piston Cylinder ◽  
Low Viscosity ◽  
Load Carrying ◽  
Surface Shaping

Oil is the main working fluid used in the hydraulics industry today — but water is nonflammable, environmentally friendly and cheap: it is the better choice of working fluid for hydraulic systems. However, there is one caveat. Water’s extremely low viscosity undermines its ability to carry load. In forest machinery, construction machinery, and aircraft systems, today’s hydraulic circuits have high operating pressures, with typical values between 300 and 420 bar. These high pressures create the need for high load-carrying abilities in the fluid films of the tribological interfaces of pumps and motors. The most challenging of these interfaces is the piston-cylinder interface of swashplate type piston machines, because the fluid must balance the entire piston side load created in this design. The low viscosity of the water turns preventing metal-to-metal contact into quite a challenge. Fortunately, an understanding of how pressure builds and shifts about in these piston-cylinder lubrication interfaces, coupled with some clever micro surface shaping, can allow engineers to drastically increase the load-carrying ability of water. As part of this research, numerous different micro surface shaping design ideas have been simulated using a highly advanced non-isothermal multi-physics model developed at the Maha Fluid Power Research Center. The model calculates leakage, power losses, film thickness and pressure buildup in the piston-cylinder interface over the course of one shaft revolution. The results allow for the comparison of different surface shapes, such as axial sine waves along the piston, or a barrel-shaped piston profile. This paper elucidates the effect of those surface profiles on pressure buildup, leakage, and torque loss in the piston-cylinder interface of an axial piston pump running at high pressure with water as the lubricant.

Analysis of High Pressure Transients in Water Hydraulic Pipeline Using Matlab/Simulink

2014 ◽  
Vol 621 ◽  
pp. 311-316
Author(s):  
Tian Yang Zhao ◽  
Dan Jiang ◽  
Song Yu ◽  
Jie Wang ◽  
Ping Yang
Keyword(s):  
Mathematical Model ◽  
High Pressure ◽  
Turbulent Flow ◽  
Weighting Function ◽  
Viscous Friction ◽  
Dynamic Friction ◽  
Matlab Simulink ◽  
Pressure Transients ◽  
Water Hydraulic ◽  
The Mathematical Model

Based on the continuity equation and the motion equation of fluid dynamics, a mathematical model of high pressure transients in water hydraulic pipeline is presented. In the model, the friction item is consist of steady friction item and dynamic friction item, using the Darcy-Weisbach equation to solve steady viscous friction item and using four exponential terms instead of weighting function to solve dynamic friction item. By finite difference method accompanied with Matlab/Simulink, an example of high pressure turbulent flow in water hydraulic pipeline is configured so as to simulate the dynamic characteristics of pressure transients. The comparison between the observed result and the simulation result shows the mathematical model of high pressure transients in water hydraulic pipeline with turbulent flow is reasonable.

scholarly journals EVALUATION ON THE CONSISTENCY OF CALIBRATION RESULTS BETWEEN REFERENCE STANDARDS OF PNEUMATIC PRESSURE BALANCE BASED ON NON-FULL RANGE CALIBRATION

2019 ◽  
Vol 21 (3) ◽  
pp. 203
Author(s):  
Adindra Vickar Ega ◽  
R.Rudi Anggoro Samodro
Keyword(s):  
High Pressure ◽  
Pressure Range ◽  
Full Range ◽  
Effective Area ◽  
National Metrology Institute ◽  
Pressure Balance ◽  
Pneumatic Pressure ◽  
Piston Cylinder ◽  
Normalized Error ◽  
High Pressure Range

<p>To provide calibration services for pressure measuring devices, SNSU-BSN has several piston-cylinder standard that may traceable to different National Metrology Institute (NMIs). Non-full range calibration of pressure balance has been performed to evaluate the consistency of calibration results between those standard, especially for establishing self-traceability in the future. In this research, a piston-cylinder unit S/N 1926 with medium pressure range of 1750 kPa, was calibrated with low pressure range S/N 978 of 350 kPa and high pressure range S/N 1054 of 7000 kPa. The calibration was performed with cross-float method to evaluate the effective area of piston-cylinder at null pressure and reference temperature of 20⁰C (<em>A<sub>0,20</sub></em>) and distortion coefficient (λ) as the 1926 main parameters. The obtained value, respectively are (1.961 166 × 10<sup>-4</sup> ± 4.4 × 10<sup>-9</sup>) m<sup>2 </sup>and (-1.67 × 10<sup>-12</sup> ± 9.4 × 10<sup>-13</sup>) Pa<sup>-1 </sup>from 978 and (1.961166 × 10<sup>-4</sup> ± 5.1 × 10<sup>-9</sup>) m<sup>2</sup> and (-1.58 × 10<sup>-12</sup> ± 8.4 × 10<sup>-13</sup>) Pa<sup>-1 </sup>from 1054. The result of 1926 from both methods shows good conformity with Normalized Error (En) of 0.0007 and 0.069, respectively. Linearity of effective area changes to the pressure is very consistent in both low and high pressure range. Validation results by using PTB-Germany results, shows the relative different for <em>A<sub>0</sub></em> and <em>λ</em> obtained are less than 0,1 × 10<sup>-6</sup> and 6%,respectively. Therefore, the pneumatic pressure balance of SNSU-BSN is traceable, consistent with each other and capable for disseminating the pressure unit along all primary pressure standard owned with high agreement compared to those of other advance NMIs.</p>

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