Dynamic Simulation Model of a Hydraulic Valve Utilizing the Ho¨rbiger Plate Principle and Piezoactuation to Achieve High Bandwidth and Flow Performance

2008 ◽  
Author(s):  
David T. Branson ◽  
Fengcai Wang ◽  
Chris R. Bowen ◽  
Patrick S. Keogh
Keyword(s):  
High Performance ◽  
Fluid Dynamic ◽  
Dynamic Simulations ◽  
Flow Rates ◽  
Pressure Drops ◽  
Dynamic Simulation Model ◽  
High Bandwidth ◽  
Performance Research ◽  
Large Flow ◽  
Hydraulic Valve

In order to increase hydraulically actuated machine system performance, valves with high performance bandwidths and large flow rates at low pressure drops are needed. While high flow rates were previously achieved using either very large spool strokes and/or diameters that would hinder valve performance, research is underway on a valve incorporating the Ho¨rbiger plate principle. This principle utilizes multiple metering edges to allow for increased flow at specified pressure drops and using small spool displacements. The valve configuration is then directly actuated using a piezoactuator to further increase valve dynamic response. This paper examines the development of a dynamic valve model using computational fluid dynamic simulations to predict fluid inertance parameters, and combines this with models for the piezoactuator, power amplifier, supply flow, fluid squeeze forces, end stop response, and valve mechanical components. Steady state and dynamic simulations of the valve are then evaluated.

A Computational Fluid Dynamic Study of a Momentum and Energy Method on Rough Surfaces

2020 ◽  
Author(s):  
Jose Urcia ◽  
Michael Kinzel
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamic ◽  
Roughness Element ◽  
Flow Rates ◽  
Pressure Drops ◽  
The Core ◽  
Roughness Elements ◽  
Momentum Correlation ◽  
The Matrix ◽  
Computational Fluid Dynamics Cfd

Abstract The Discrete Element Roughness Method (DERM) has been used to improve convective heat transfer predictions on surface roughness. This work aims to validate the core momentum-correlation of DERM through evaluating Computational fluid dynamics (CFD)-based solution of the flow around individual roughness elements with the goal of improving the correlations. More specifically, the matrix of scenarios evaluated using includes three different roughness elements at three different pressure drops (or flow rates). Results from these studies are to be used to validate and improve correlations used to approximate roughness in DERM. For further comparison, a fourth roughness element analyzed in previous work will also be compared. For each element, a steady and unsteady case are conducted and analyzed. The momentum loss results obtained from the CFD are then compared to the DERM-based predictions from the same roughness elements in search of any discrepancies. It is observed the momentum-correlation deviates from the CFD prediction with increasing element height.

scholarly journals Numerical Optimization of a Stall Margin Enhancing Recirculation Channel for an Axial Compressor

Fluids ◽  
2019 ◽  
Vol 4 (2) ◽  
pp. 88
Author(s):  
Motoyuki Kawase ◽  
Aldo Rona
Keyword(s):  
High Speed ◽  
High Performance ◽  
Fluid Dynamic ◽  
Axial Compressor ◽  
Leading Edge ◽  
Navier Stokes ◽  
Test Case ◽  
Dynamic Simulations ◽  
Stall Margin ◽  
Casing Treatment

A proof of concept is provided by computational fluid dynamic simulations of a new recirculating type casing treatment. This treatment aims at extending the stable operating range of highly loaded axial compressors, so to improve the safety of sorties of high-speed, high-performance aircraft powered by high specific thrust engines. This casing treatment, featuring an axisymmetric recirculation channel, is evaluated on the NASA rotor 37 test case by steady and unsteady Reynolds Averaged Navier Stokes (RANS) simulations, using the realizable k-ε model. Flow blockage at the recirculation channel outlet was mitigated by chamfering the exit of the recirculation channel inner wall. The channel axial location from the rotor blade tip leading edge was optimized parametrically over the range −4.6% to 47.6% of the rotor tip axial chord c z . Locating the channel at 18.2% c z provided the best stall margin gain of approximately 5.5% compared to the untreated rotor. No rotor adiabatic efficiency was lost by the application of this casing treatment. The investigation into the flow structure with the recirculating channel gave a good insight into how the new casing treatment generates this benefit. The combination of stall margin gain at no rotor adiabatic efficiency loss makes this design attractive for applications to high-speed gas turbine engines.

scholarly journals Micro-Scale Permeability Characterization of Carbon Fiber Composites Using Micrograph Volume Elements

2021 ◽  
Vol 8 ◽  
Author(s):  
Julian Seuffert ◽  
Lars Bittrich ◽  
Leonardo Cardoso de Oliveira ◽  
Axel Spickenheuer ◽  
Luise Kärger
Keyword(s):  
High Performance ◽  
Fluid Dynamic ◽  
Stochastic Approach ◽  
Carbon Fiber Composites ◽  
Liquid Composite Molding ◽  
Fiber Distribution ◽  
Dynamic Simulations ◽  
Micro Scale ◽  
Fiber Placement ◽  
Reinforced Plastics

To manufacture a high-performance structure made of continuous fiber reinforced plastics, Liquid Composite Molding processes are used, where a liquid resin infiltrates the dry fibers. For a good infiltration quality without dry spots, it is important to predict the resin flow correctly. Knowledge of the local permeability is an essential precondition for mold-filling simulations. In our approach, the intra-bundle permeability parallel and transverse to the fibers is characterized via periodic fluid dynamic simulations of micro-scale volume elements (VE). We evaluate and compare two approaches: First, an approach to generate VEs based on a statistical distribution of the fibers and fiber diameters. Second, an approach based on micrograph images of samples manufactured with Tailored Fiber Placement (TFP) using the measured fiber distribution. The micrograph images show a higher heterogeneity of the distribution than the statistically generated VEs, which is characterized by large resin areas. This heterogeneity leads to a significantly different permeability compared to the stochastic approach. In conclusion, a pure stochastic approach needs to contain the large heterogeneity of the fiber distribution to predict correct permeability values.

The Use of Hydrostatic Thrust Bearing in Flow and Temperature Measurements

1975 ◽  
Vol 97 (1) ◽  
pp. 116-120
Author(s):  
S. A. Morsi
Keyword(s):  
Temperature Sensor ◽  
Thrust Bearing ◽  
Temperature Measurements ◽  
Flow Rates ◽  
Pressure Drops ◽  
Small Pressure ◽  
Constant Resistance ◽  
And Performance ◽  
New Applications ◽  
Large Flow

This paper describes two new applications for the hydrostatic thrust bearing. The first application is the use of the bearing, when the gap is fixed, as a linear constant resistance. Several bearings have been connected together in parallel to obtain large flow rates at small pressure drops for use as a flowmeter. The second application is the use of a bearing, when modified, as a temperature sensor. Description and performance of this modified design when used as a temperature sensor are given.

scholarly journals Numerical Evaluation of a HVAC System Based on a High-Performance Heat Transfer Fluid

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3298
Author(s):  
Gianpiero Colangelo ◽  
Brenda Raho ◽  
Marco Milanese ◽  
Arturo de Risi
Keyword(s):  
Heat Transfer ◽  
High Performance ◽  
Cooling System ◽  
Electrical Energy ◽  
Simulation Software ◽  
Heat Transfer Fluid ◽  
Hvac System ◽  
Dynamic Simulations ◽  
Heating And Cooling ◽  
The University

Nanofluids have great potential to improve the heat transfer properties of liquids, as demonstrated by recent studies. This paper presents a novel idea of utilizing nanofluid. It analyzes the performance of a HVAC (Heating Ventilation Air Conditioning) system using a high-performance heat transfer fluid (water-glycol nanofluid with nanoparticles of Al2O3), in the university campus of Lecce, Italy. The work describes the dynamic model of the building and its heating and cooling system, realized through the simulation software TRNSYS 17. The use of heat transfer fluid inseminated by nanoparticles in a real HVAC system is an innovative application that is difficult to find in the scientific literature so far. This work focuses on comparing the efficiency of the system working with a traditional water-glycol mixture with the same system that uses Al2O3-nanofluid. The results obtained by means of the dynamic simulations have confirmed what theoretically assumed, indicating the working conditions of the HVAC system that lead to lower operating costs and higher COP and EER, guaranteeing the optimal conditions of thermo-hygrometric comfort inside the building. Finally, the results showed that the use of a nanofluid based on water-glycol mixture and alumina increases the efficiency about 10% and at the same time reduces the electrical energy consumption of the HVAC system.

Towards real-time fire data synthesis using numerical simulations

2021 ◽  
pp. 073490412199344
Author(s):  
Wolfram Jahn ◽  
Frane Sazunic ◽  
Carlos Sing-Long
Keyword(s):  
Real Time ◽  
Computational Fluid Dynamic ◽  
Dynamic Models ◽  
Fluid Dynamic ◽  
Near Field ◽  
Computing Time ◽  
Temperature Correction ◽  
Dynamic Simulations ◽  
Conservation Of Energy ◽  
Fire Scenarios

Synthesising data from fire scenarios using fire simulations requires iterative running of these simulations. For real-time synthesising, faster-than-real-time simulations are thus necessary. In this article, different model types are assessed according to their complexity to determine the trade-off between the accuracy of the output and the required computing time. A threshold grid size for real-time computational fluid dynamic simulations is identified, and the implications of simplifying existing field fire models by turning off sub-models are assessed. In addition, a temperature correction for two zone models based on the conservation of energy of the hot layer is introduced, to account for spatial variations of temperature in the near field of the fire. The main conclusions are that real-time fire simulations with spatial resolution are possible and that it is not necessary to solve all fine-scale physics to reproduce temperature measurements accurately. There remains, however, a gap in performance between computational fluid dynamic models and zone models that must be explored to achieve faster-than-real-time fire simulations.

scholarly journals Analysis of Radial Inflow Turbine Losses Operating with Supercritical Carbon Dioxide

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3561
Author(s):  
Antti Uusitalo ◽  
Aki Grönman
Keyword(s):  
Fluid Dynamic ◽  
Dynamic Simulations ◽  
Average Deviation ◽  
Loss Analysis ◽  
Specific Speed ◽  
Loss Models ◽  
Rotor Losses ◽  
Radial Turbines ◽  
Design Power ◽  
Good Agreement

The losses of supercritical CO2 radial turbines with design power scales of about 1 MW were investigated by using computational fluid dynamic simulations. The simulation results were compared with loss predictions from enthalpy loss correlations. The aim of the study was to investigate how the expansion losses are divided between the stator and rotor as well as to compare the loss predictions obtained with the different methods for turbine designs with varying specific speeds. It was observed that a reasonably good agreement between the 1D loss correlations and computational fluid dynamics results can be obtained by using a suitable set of loss correlations. The use of different passage loss models led to high deviations in the predicted rotor losses, especially with turbine designs having the highest or lowest specific speeds. The best agreement in respect to CFD results with the average deviation of less than 10% was found when using the CETI passage loss model. In addition, the other investigated passage loss models provided relatively good agreement for some of the analyzed turbine designs, but the deviations were higher when considering the full specific speed range that was investigated. The stator loss analysis revealed that despite some differences in the predicted losses between the methods, a similar trend in the development of the losses was observed as the turbine specific speed was changed.

Computational fluid dynamic simulations of coal-fired utility boilers: An engineering tool

Fuel ◽  
2009 ◽  
Vol 88 (1) ◽  
pp. 9-18 ◽  
Author(s):  
Efim Korytnyi ◽  
Roman Saveliev ◽  
Miron Perelman ◽  
Boris Chudnovsky ◽  
Ezra Bar-Ziv
Keyword(s):  
Computational Fluid Dynamic ◽  
Fluid Dynamic ◽  
Dynamic Simulations ◽  
Utility Boilers
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