A numerical study on the aerodynamic characteristics of a variable geometry throttle valve(VGTV) system controlling air-flow rate

2013 ◽  
Vol 37 (4) ◽  
pp. 378-383
Author(s):  
Hyun-Sung Cho ◽  
Chul-Ho Kim
Keyword(s):  
Flow Rate ◽  
Numerical Study ◽  
Air Flow ◽  
Aerodynamic Characteristics ◽  
Variable Geometry ◽  
Air Flow Rate ◽  
Throttle Valve

scholarly journals Model of thermal buoyancy in cavity-ventilated roof constructions

2021 ◽  
pp. 174425912098418
Author(s):  
Toivo Säwén ◽  
Martina Stockhaus ◽  
Carl-Eric Hagentoft ◽  
Nora Schjøth Bunkholt ◽  
Paula Wahlgren
Keyword(s):  
Analytical Model ◽  
Flow Rate ◽  
Numerical Study ◽  
Air Flow ◽  
Wind Pressure ◽  
Air Flow Rate ◽  
Test Set ◽  
Air Cavity ◽  
Thermal Buoyancy ◽  
The Impact

Timber roof constructions are commonly ventilated through an air cavity beneath the roof sheathing in order to remove heat and moisture from the construction. The driving forces for this ventilation are wind pressure and thermal buoyancy. The wind driven ventilation has been studied extensively, while models for predicting buoyant flow are less developed. In the present study, a novel analytical model is presented to predict the air flow caused by thermal buoyancy in a ventilated roof construction. The model provides means to calculate the cavity Rayleigh number for the roof construction, which is then correlated with the air flow rate. The model predictions are compared to the results of an experimental and a numerical study examining the effect of different cavity designs and inclinations on the air flow rate in a ventilated roof subjected to varying heat loads. Over 80 different test set-ups, the analytical model was found to replicate both experimental and numerical results within an acceptable margin. The effect of an increased total roof height, air cavity height and solar heat load for a given construction is an increased air flow rate through the air cavity. On average, the analytical model predicts a 3% higher air flow rate than found in the numerical study, and a 20% lower air flow rate than found in the experimental study, for comparable test set-ups. The model provided can be used to predict the air flow rate in cavities of varying design, and to quantify the impact of suggested roof design changes. The result can be used as a basis for estimating the moisture safety of a roof construction.

Modeling of Variable Inlet Guide Vanes Affects on a One Shaft Industrial Gas Turbine Used in a Combined Cycle Application

2008 ◽  
Author(s):  
Cesar Celis ◽  
Paula de M. Ribeiro Pinto ◽  
Rafael S. Barbosa ◽  
Sandro B. Ferreira
Keyword(s):  
Gas Turbine ◽  
Flow Rate ◽  
Air Flow ◽  
Combined Cycle ◽  
Variable Geometry ◽  
Correction Factors ◽  
Air Flow Rate ◽  
Design Point ◽  
Inlet Guide Vanes ◽  
Industrial Gas Turbine

It is well known that gas turbine simulation involves satisfying the conditions of compatibility between its components. At design point, the components are all well matched and working at high efficiency regions. However, at steady state off-design, due to the compatibility issues and changes in operating parameters, basically turbine entry temperature and pressure ratio to attain a certain load, it is possible that the components may be working within regions of low efficiency. A reason for this phenomenon is that the flow areas at the various sections of the engine correspond to that at design point, such that operation at off-design is restricted. One way to widen the operational envelope of an engine is varying these flow areas, providing a good match between the gas turbine components. A widely used type of variable geometry which has attracted a great amount of interest is the use of compressor variable geometry, the so called variable inlet guide vanes (VIGVs), as a power control strategy, which involves the control of the air flow rate entering the compressor and the power output modulation at constant rotational speed. The purpose of the air flow rate modulation is to enhance the heat recovery performance and thus increase the combined cycle efficiency by maintaining high turbine exhaust temperature. One methodology used to model a variable geometry compressor, in the absence of its geometric data involves the use of correction factors, as functions of the VIGV change. Fundamentally, this methodology assumes that each new position of the VIGVs represents a new machine, i.e., a new design point, such that its original map of characteristics is displaced in order to describe this “new” compressor. The purpose of this work is to analyze the influence of the use of different functions for these correction factors on a W501F (one shaft, industrial) gas turbine simulation. An in-house computer program developed for performance modeling of gas turbines was utilized to carry out the simulations. The results provided by this computer code show good agreement with operational data, indicating that, although more tests must be conducted, the methodology seems to be reliable enough for the aims of the project for which it has been developed.

A Numerical Study of the Effect of Bubble Layer on Propulsion Performance of Deep-Vee Hull Form Ship

2012 ◽  
Vol 479-481 ◽  
pp. 2551-2556
Author(s):  
Qi Yao Li ◽  
Ou Yongpeng
Keyword(s):  
Flow Rate ◽  
Liquid Mixture ◽  
Numerical Study ◽  
Air Flow ◽  
Open Water ◽  
Air Flow Rate ◽  
Hull Form ◽  
Propulsion Performance ◽  
Water Conditions ◽  
Bubble Layer

A numerical study of the effect of Bubble Layer on Propulsion performance is carried out by using the Air-Liquid Mixture Model. The effect of factors, such as air flow rate, air injected positions on propulsion performance are investigated. The following findings are obtained: (1) In the open water conditions, the air injected inlet is farther away from the propeller center, the little more effect on the propulsion performance; Along with the increase of air flow, the effect of bubbly layer on the propulsion performance increases slightly. (2)Because of the hull form and the clearance between the bottom and the blades tip, bubble layer has small effect on propulsion performance of deep-vee hull form ship propelled by propeller.

scholarly journals Modeling and optimization of radish root extract drying as peroxidase source using spouted bed dryer

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shahrbanoo Hamedi ◽  
M. Mehdi Afsahi ◽  
Ali Riahi-Madvar ◽  
Ali Mohebbi
Keyword(s):  
Kinetic Parameters ◽  
Flow Rate ◽  
Air Flow ◽  
Cost Effective ◽  
Industrial Applications ◽  
Interactive Effects ◽  
Root Extract ◽  
Air Flow Rate ◽  
Spouted Bed ◽  
Radish Root

AbstractThe main advantages of the dried enzymes are the lower cost of storage and longer time of preservation for industrial applications. In this study, the spouted bed dryer was utilized for drying the garden radish (Raphanus sativus L.) root extract as a cost-effective source of the peroxidase enzyme. The response surface methodology (RSM) was used to evaluate the individual and interactive effects of main parameters (the inlet air temperature (T) and the ratio of air flow rate to the minimum spouting air flow rate (Q)) on the residual enzyme activity (REA). The maximum REA of 38.7% was obtained at T = 50 °C and Q = 1.4. To investigate the drying effect on the catalytic activity, the optimum reaction conditions (pH and temperature), as well as kinetic parameters, were investigated for the fresh and dried enzyme extracts (FEE and DEE). The obtained results showed that the optimum pH of DEE was decreased by 12.3% compared to FEE, while the optimum temperature of DEE compared to FEE increased by a factor of 85.7%. Moreover, kinetic parameters, thermal-stability, and shelf life of the enzyme were considerably improved after drying by the spouted bed. Overall, the results confirmed that a spouted bed reactor can be used as a promising method for drying heat-sensitive materials such as peroxidase enzyme.

Method to Determine an Optimal Air-Flow Rate in Solar Collectors

1979 ◽  
Vol 3 (6) ◽  
pp. 357-362
Author(s):  
H. C. Hewitt ◽  
E. I. Griggs
Keyword(s):  
Flow Rate ◽  
Air Flow ◽  
Solar Collectors ◽  
Air Flow Rate

Model-Based Analysis of Transient Behavior of Large Scale CFB Boilers

2003 ◽  
Author(s):  
Ari Kettunen ◽  
Timo Hyppa¨nen ◽  
Ari-Pekka Kirkinen ◽  
Esa Maikkola
Keyword(s):  
Flow Rate ◽  
Large Scale ◽  
Air Flow ◽  
Model Parameters ◽  
Air Flow Rate ◽  
Process Data ◽  
Cfb Boiler ◽  
Flow Rates ◽  
Load Change ◽  
Secondary Air

The main objective of this study was to investigate the load change capability and effect of the individual control variables, such as fuel, primary air and secondary air flow rates, on the dynamics of large-scale CFB boilers. The dynamics of the CFB process were examined by dynamic process tests and by simulation studies. A multi-faceted set of transient process tests were performed at a commercial 235 MWe CFB unit. Fuel reactivity and interaction between gas flow rates, solid concentration profiles and heat transfer were studied by step changes of the following controllable variables: fuel feed rate, primary air flow rate, secondary air flow rate and primary to secondary air flow ratio. Load change performance was tested using two different types of tests: open and closed loop load changes. A tailored dynamic simulator for the CFB boiler was built and fine-tuned by determining the model parameters and by validating the models of each process component against measured process data of the transient test program. The know-how about the boiler dynamics obtained from the model analysis and the developed CFB simulator were utilized in designing the control systems of three new 262 MWe CFB units, which are now under construction. Further, the simulator was applied for the control system development and transient analysis of the supercritical OTU CFB boiler.

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