The impact of an additional inlet point on the hot outlet side on the vortex tube productivity

2019 ◽  
Vol 14 (3) ◽  
pp. 176-183
Author(s):  
L.Yu. Privalov ◽  
C.I. Mikhaylenko
Keyword(s):  
Vortex Tube ◽  
Computation Time ◽  
Ideal Gas ◽  
Effective Length ◽  
Tube Length ◽  
Inlet Channel ◽  
Air Inlet ◽  
Hot Air ◽  
Speed Up ◽  
The Impact

Based on numerical simulation, the production of cold and hot air on a modified countercurrent vortex tube is studied. A feature of the modification under study is an additional air inlet area along the axis of the pipe from the hot outlet side. An additional point of blowing air is designed to redistribute the gas flows at the cold and hot outlets. Computational experiments were performed in the OpenFOAM software package using the sonicFoam solver based on the k−ε turbulence model under the assumption of an ideal gas. The dependence of the flow rate and temperature at the cold and hot outlets for different lengths of the main channel of the vortex tube was studied. For all considered pipe lengths, finite-volume grids were prepared in which the rectangular shape of the cells was preferably observed and their excessive stretching was avoided. To speed up the simulations, MPI technology was used; spatial decomposition of the original mesh was performed by decomposePar utility into equal parts along the pipe. This approach allowed us to reduce the computation time by approximately 3.5 times when running on six processes. The results of parallel modeling were combined with the reconstructPar utility and further processed by a Python program written using the vtk library. Thus, average values of the main physical characteristics by time and space at the cold and hot outlets were obtained. Results are discussed that demonstrate the effect of the vortex tube length on temperature and air flow at the respective outputs. The behavior of its main characteristics, non-standard for a vortex tube, is shown, an assumption is made about the reason for this behavior: the collision of very fast flows makes instability. Preliminary conclusions are made about choosing the effective length of the vortex tube with an additional air inlet channel at which the ratio of air temperature at the hot and cold outlets is the largest.

scholarly journals Effect of DEM Resolution on Runoff Yield, and Sensitivity of Parameters Contributing to Runoff in a Watershed

2019 ◽  
Author(s):  
Mohammad Nazari-Sharabian ◽  
Moses Karakouzian ◽  
Sajjad Ahmad
Keyword(s):  
Assessment Tool ◽  
Space Shuttle ◽  
Computation Time ◽  
Shuttle Radar Topography Mission ◽  
Alos Palsar ◽  
Dem Resolution ◽  
Digital Elevation ◽  
Speed Up ◽  
Sensitive Parameters ◽  
The Impact

Digital Elevation Models (DEMs) are essential in watershed delineation, but the sensitivity of simulated runoff to DEM resolution is poorly understood. This study investigates the impact of DEM resolution on topological attributes and simulated runoff in the Mahabad Dam watershed, Iran. To delineate the watershed, DEMs with 12.5 m, 30 m, and 90 m resolutions were acquired from the ALOS PALSAR, Space Shuttle Radar Topography Mission (SRTM), and ASTER global DEM data source, respectively. Watershed and streamlines were delineated in ArcGIS, with hydrologic analyses performed using the Soil and Water Assessment Tool (SWAT). Sensitivity analysis on parameters contributing to runoff was done using Sequential Uncertainties Fitting Ver-2 (SUFI-2) Algorithm, in SWAT Calibration and Uncertainty Procedures (SWAT-CUP) software. Results showed the watershed area, reach lengths, and elevations in the watershed varied due to DEM resolutions. Higher amounts of runoff were generated when DEMs with finer resolutions were implemented. The 12.5 m DEM generated 3.48% and 0.42% more runoff compared with 90 m and 30 m DEMs, respectively. SWAT-CUP results showed the sensitivity of parameters contributing to runoff changes under different DEM resolutions. Regardless of DEM resolution, surface properties, available water capacity, and moisture levels in the soil are the most sensitive parameters. As the distribution of slope changes in different DEM resolutions, surface parameters are most affected. The findings indicate to reduce computation time and speed up computation procedures, researchers may use DEMs with coarser resolutions at the expense of minor decreases in accuracy.

The influence of the vortex tube channel length on the separation of air by its temperature

2019 ◽  
Vol 14 (1) ◽  
pp. 36-43
Author(s):  
B.R. Adiullin ◽  
C.I. Mikhaylenko
Keyword(s):  
Atmospheric Pressure ◽  
Constant Pressure ◽  
Vortex Tube ◽  
Channel Length ◽  
Ideal Gas ◽  
Hot Air ◽  
Conservation Of Momentum ◽  
Mass Flow Rates ◽  
Vortex Tubes ◽  
Tube Channel

Based on the prepared counterflow vortex tube model with four inlets, the effect of the length of the vortex tube channel on the generation of cold and hot air is investigated. In the simulation were used standard equations of gas dynamics, which include the equations of continuity, conservation of momentum, total energy, and the state of an ideal gas. To consider turbulent effects was chosen a -\varepsilon$ turbulence model. Computational experiments were carried out in the OpenFOAM software using the sonicFoam solver. The prepared grid allowed modeling vortex tubes with the main channel length varying from 20 to 70 cm. All calculations were carried out under the same boundary conditions with constant pressure at the inlets and atmospheric pressure at the hot and cold outlets. The constructed model adequately reproduces the two-vortex structure of the air flow in the vortex tube. To obtain and process the results were used OpenFOAM utilities and a script implementing the algorithm for averaging the values at the tube outlets written in Python. The results were obtained on the temperatures and mass flow rates of air in cold and hot outlets of the vortex tube depending on the length of the device. According to the analysis of the obtained data, it was shown that increasing the length of the channel of the vortex tube significantly increases the production of cold air with a certain increase in its temperature. An increase in the temperature of the produced hot air with an increase in the length of the vortex tube was also noted.

Methods for Restricting Maximum Exposure Rate in Computerized Adaptative Testing

Methodology ◽  
2007 ◽  
Vol 3 (1) ◽  
pp. 14-23 ◽  
Author(s):  
Juan Ramon Barrada ◽  
Julio Olea ◽  
Vicente Ponsoda
Keyword(s):  
Measurement Accuracy ◽  
Computerized Adaptive Testing ◽  
Computation Time ◽  
Adaptive Testing ◽  
Exposure Rate ◽  
Control Parameters ◽  
The Impact ◽  
Two Alternatives ◽  
Selection Of ◽  
Maximum Exposure

Abstract. The Sympson-Hetter (1985) method provides a means of controlling maximum exposure rate of items in Computerized Adaptive Testing. Through a series of simulations, control parameters are set that mark the probability of administration of an item on being selected. This method presents two main problems: it requires a long computation time for calculating the parameters and the maximum exposure rate is slightly above the fixed limit. Van der Linden (2003) presented two alternatives which appear to solve both of the problems. The impact of these methods in the measurement accuracy has not been tested yet. We show how these methods over-restrict the exposure of some highly discriminating items and, thus, the accuracy is decreased. It also shown that, when the desired maximum exposure rate is near the minimum possible value, these methods offer an empirical maximum exposure rate clearly above the goal. A new method, based on the initial estimation of the probability of administration and the probability of selection of the items with the restricted method ( Revuelta & Ponsoda, 1998 ), is presented in this paper. It can be used with the Sympson-Hetter method and with the two van der Linden's methods. This option, when used with Sympson-Hetter, speeds the convergence of the control parameters without decreasing the accuracy.

Assessing the Impact of the Inlet Total Pressure Distortion on the Turbofan Thrust

2018 ◽  
pp. 19-30
Author(s):  
Yu. A. Ezrokhi ◽  
E. A. Khoreva
Keyword(s):  
Total Pressure ◽  
External Compression ◽  
Average Value ◽  
Inlet Distortion ◽  
Air Inlet ◽  
Engine Thrust ◽  
Relative Value ◽  
Main Effect ◽  
Pressure Recovery Factor ◽  
The Impact

The paper considers techniques to develop a mathematical model using a method of «parallel compressors». The model is intended to estimate the impact of the air inlet distortion on the primary parameters of the aero-engine.  The paper presents rated estimation results in the context of twin spool turbofan design for two typical cruiser modes of flight of the supersonic passenger jet. In estimation the base values σbase and the average values of the inlet ram recovery σave remained invariable. Thus, parametrical calculations were performed for each chosen relative value of the area of low-pressure region.The paper shows that an impact degree of the inlet distortion on the engine thrust for two modes under consideration is essentially different. In other words, if in the subsonic mode the impact assessment can be confined only to taking into account the influence of decreasing average values of the inlet total pressure, the use of such an assumption in the supersonic cruiser mode may result in considerable errors.With invariable values of the pressure recovery factor at the engine intake, which correspond to the speed of flight for a typical air inlet of external compression σbase, and average value σave, a parameter Δσuneven  has the main effect on the engine thrust, and degree of this effect essentially depends on a difference between σave and σbase values.

scholarly journals Shock interactions in inviscid air and $$\hbox {CO}_2$$–$$\hbox {N}_2$$ flows in thermochemical non-equilibrium

Shock Waves ◽  
2021 ◽  
Author(s):  
C. Garbacz ◽  
W. T. Maier ◽  
J. B. Scoggins ◽  
T. D. Economon ◽  
T. Magin ◽  
...  
Keyword(s):  
Chemical Species ◽  
High Energy ◽  
Ideal Gas ◽  
Shock Interaction ◽  
Interaction Patterns ◽  
Shock Interactions ◽  
Wave Interference ◽  
Type V ◽  
The Impact ◽  
Non Equilibrium

AbstractThe present study aims at providing insights into shock wave interference patterns in gas flows when a mixture different than air is considered. High-energy non-equilibrium flows of air and $$\hbox {CO}_2$$ CO 2 –$$\hbox {N}_2$$ N 2 over a double-wedge geometry are studied numerically. The impact of freestream temperature on the non-equilibrium shock interaction patterns is investigated by simulating two different sets of freestream conditions. To this purpose, the SU2 solver has been extended to account for the conservation of chemical species as well as multiple energies and coupled to the Mutation++ library (Multicomponent Thermodynamic And Transport properties for IONized gases in C++) that provides all the necessary thermochemical properties of the mixture and chemical species. An analysis of the shock interference patterns is presented with respect to the existing taxonomy of interactions. A comparison between calorically perfect ideal gas and non-equilibrium simulations confirms that non-equilibrium effects greatly influence the shock interaction patterns. When thermochemical relaxation is considered, a type VI interaction is obtained for the $$\hbox {CO}_2$$ CO 2 -dominated flow, for both freestream temperatures of 300 K and 1000 K; for air, a type V six-shock interaction and a type VI interaction are obtained, respectively. We conclude that the increase in freestream temperature has a large impact on the shock interaction pattern of the air flow, whereas for the $$\hbox {CO}_2$$ CO 2 –$$\hbox {N}_2$$ N 2 flow the pattern does not change.

scholarly journals Comprehensive Thermodynamic Analysis of the Humphrey Cycle for Gas Turbines with Pressure Gain Combustion

Energies ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 3521 ◽  
Author(s):  
Panagiotis Stathopoulos
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Combustion Process ◽  
Ideal Gas ◽  
Point Of View ◽  
Pressure Gain Combustion ◽  
Combustion Technology ◽  
Secondary Air ◽  
And Performance ◽  
The Impact

Conventional gas turbines are approaching their efficiency limits and performance gains are becoming increasingly difficult to achieve. Pressure Gain Combustion (PGC) has emerged as a very promising technology in this respect, due to the higher thermal efficiency of the respective ideal gas turbine thermodynamic cycles. Up to date, only very simplified models of open cycle gas turbines with pressure gain combustion have been considered. However, the integration of a fundamentally different combustion technology will be inherently connected with additional losses. Entropy generation in the combustion process, combustor inlet pressure loss (a central issue for pressure gain combustors), and the impact of PGC on the secondary air system (especially blade cooling) are all very important parameters that have been neglected. The current work uses the Humphrey cycle in an attempt to address all these issues in order to provide gas turbine component designers with benchmark efficiency values for individual components of gas turbines with PGC. The analysis concludes with some recommendations for the best strategy to integrate turbine expanders with PGC combustors. This is done from a purely thermodynamic point of view, again with the goal to deliver design benchmark values for a more realistic interpretation of the cycle.

Abstract 313: Nonionic Acid is a Target Metabolite of Diabetic Microvasculopathy

2016 ◽  
Vol 119 (suppl_1) ◽  
Author(s):  
Yasuko K Bando ◽  
Haruya Kawase ◽  
Kazuyuki Nishimura ◽  
Akio Monji ◽  
Toyoaki Murohara
Keyword(s):  
Diabetic Microangiopathy ◽  
Tube Length ◽  
Nonanoic Acid ◽  
Branch Points ◽  
Metabolome Analysis ◽  
Whole Heart ◽  
The Impact ◽  
Type 2 Diabetic

Aim: The purpose of this study is to screen the target metabolites of diabetic microangiopathy in heart by use of whole heart metabolome analysis. Methods: Diet-induced type 2 diabetic mouse were divided into two groups; control and those treated with diabetic remedy GLP-1 receptor agonist Ex-4 for 5 weeks. Mice were euthanized and analyzed at the age of 16 week-old. Results: The capillary density of the T2DM was reduced as compared to those non-diabetic counterparts, which was restored by Ex4 treatment. Changes in angiogenic signals detected by immunoblotting analysis revealed that the phosphorylation levels of eNOS and AMPK were elevated by Ex-4, but those Akt remained unchanged. Tube formation assay revealed that Ex-4 increased tube length and branch points in HUVECs. Consistently with the trend that was observed in vivo experiment, AMPK and eNOS phosphorylation levels were enhanced by Ex4 without affecting Akt phosphorylation. To screen the candidate metabolites that is responsible for the diabetic microvasculopathy in GLP-1-dependent fashion, we performed metabolome analysis by using the whole heart of each mouse. The hierarchical cluster analysis revealed that nonanoic acid (NNA) was the only metabolite that increased in type 2 diabetic mice with concomitant decline by Ex-4 treatment. We next examined the impact of nonanoic acid on in vitro angiogenesis and found that NNA suppressed tube length and branch points in HUVECs in a dose-dependent fashion. Interestingly, NNA canceled eNOS and AMPK phosphorylation that was enhanced by Ex4. Conclusion: GLP-1 ameliorated diabetic microvasculopathy via the AMPK and eNOS axis. NNA is presumably one of the novel anti-angiogenic metabolites that causes diabetic microangiopathy.

scholarly journals Parallel Algorithms for Spatial Rainfall Distribution

Jurnal INKOM ◽  
2014 ◽  
Vol 8 (1) ◽  
pp. 29 ◽  
Author(s):  
Arnida Lailatul Latifah ◽  
Adi Nurhadiyatna
Keyword(s):  
Parallel Algorithms ◽  
Computation Time ◽  
Computational Time ◽  
Rainfall Distribution ◽  
Flood Modelling ◽  
Computation Efficiency ◽  
Distance Weighting ◽  
Speed Up ◽  
Important Input ◽  
Serial Algorithms

This paper proposes parallel algorithms for precipitation of flood modelling, especially applied in spatial rainfall distribution. As an important input in flood modelling, spatial distribution of rainfall is always needed as a pre-conditioned model. In this paper two interpolation methods, Inverse distance weighting (IDW) and Ordinary kriging (OK) are discussed. Both are developed in parallel algorithms in order to reduce the computational time. To measure the computation efficiency, the performance of the parallel algorithms are compared to the serial algorithms for both methods. Findings indicate that: (1) the computation time of OK algorithm is up to 23% longer than IDW; (2) the computation time of OK and IDW algorithms is linearly increasing with the number of cells/ points; (3) the computation time of the parallel algorithms for both methods is exponentially decaying with the number of processors. The parallel algorithm of IDW gives a decay factor of 0.52, while OK gives 0.53; (4) The parallel algorithms perform near ideal speed-up.

scholarly journals Hyper-optimized tensor network contraction

Quantum ◽  
2021 ◽  
Vol 5 ◽  
pp. 410
Author(s):  
Johnnie Gray ◽  
Stefanos Kourtis
Keyword(s):  
Computation Time ◽  
Quantum Circuit ◽  
Optimization Approach ◽  
Many Body ◽  
Tensor Networks ◽  
Randomized Protocols ◽  
Classical Simulation ◽  
Tensor Network ◽  
Speed Up ◽  
Many Body Systems

Tensor networks represent the state-of-the-art in computational methods across many disciplines, including the classical simulation of quantum many-body systems and quantum circuits. Several applications of current interest give rise to tensor networks with irregular geometries. Finding the best possible contraction path for such networks is a central problem, with an exponential effect on computation time and memory footprint. In this work, we implement new randomized protocols that find very high quality contraction paths for arbitrary and large tensor networks. We test our methods on a variety of benchmarks, including the random quantum circuit instances recently implemented on Google quantum chips. We find that the paths obtained can be very close to optimal, and often many orders or magnitude better than the most established approaches. As different underlying geometries suit different methods, we also introduce a hyper-optimization approach, where both the method applied and its algorithmic parameters are tuned during the path finding. The increase in quality of contraction schemes found has significant practical implications for the simulation of quantum many-body systems and particularly for the benchmarking of new quantum chips. Concretely, we estimate a speed-up of over 10,000× compared to the original expectation for the classical simulation of the Sycamore `supremacy' circuits.

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