scholarly journals Measuring Pressure Drop Under Non Ideal Conditions

2006 ◽  
Vol 22 (1) ◽  
pp. 6-12
Author(s):  
M Austin
Keyword(s):  
Pressure Drop ◽  
Environmental Effects ◽  
Task Force ◽  
Measurement Procedure ◽  
Measuring Instrument ◽  
Atmospheric Conditions ◽  
Measurement Instruments ◽  
Cigarette Filter ◽  
Calibration Methods ◽  
Method Of Measurement

AbstractThe method of measurement of the pressure drop (PD) of cigarette filter rods and the draw resistance of cigarettes is defined in ISO 6565-2002 (1). This standard defines the calibration and use of a transfer standard to calibrate the measuring instrument and also defines the measurement procedure for cigarette and filter samples. The procedure described in the standard assumes that the measurement conditions are constant and that the sample is in equilibrium with the measurement environment.In 2001, the Cooperation Center for Scientific Research Relative to Tobacco (CORESTA) formed a Task Force to investigate the problems associated with the calibration of PD transfer standards that are caused, primarily, by environmental effects. The work of this task force has lead to the harmonisation of the calibration methods between supplier laboratories and to a method for compensation for the effects of atmospheric conditions. These together have considerably reduced the inter-laboratory differences and will eventually lead to a revision of the CORESTA Recommended Method and ISO 6565 Standard.During the work of this Task Force, it has become evident that further work will be necessary to deal with similar errors encountered during the calibration of PD measurement instruments and during the PD measurement of cigarette and filter rod samples. These errors occur in real measurement situations due to the problems in meeting the ISO 6565 conditions and other necessary requirements. This can give rise to errors in the indicated PD and can considerably degrade the confidence that can be placed in the results.This paper examines many of the practical problems in the measurement of PD and attempts to estimate the type and magnitude of the errors that might be experienced.

Stable Calibrations of Six-DOF Serial Robots by Using Identification Models with Equalized Singular Values

Robotica ◽  
2021 ◽  
pp. 1-22
Author(s):  
Zhouxiang Jiang ◽  
Min Huang
Keyword(s):  
Industrial Robot ◽  
Singular Values ◽  
Calibration Method ◽  
Identification Accuracy ◽  
Condition Numbers ◽  
Measurement Instruments ◽  
Unknown Parameters ◽  
Calibration Methods ◽  
Six Dof ◽  
The Stability

SUMMARY In typical calibration methods (kinematic or non-kinematic) for serial industrial robot, though measurement instruments with high resolutions are adopted, measurement configurations are optimized, and redundant parameters are eliminated from identification model, calibration accuracy is still limited under measurement noise. This might be because huge gaps still exist among the singular values of typical identification Jacobians, thereby causing the identification models ill conditioned. This paper addresses such problem by using new identification models established in two steps. First, the typical models are divided into the submodels with truncated singular values. In this way, the unknown parameters corresponding to the abnormal singular values are removed, thereby reducing the condition numbers of the new submodels. However, these models might still be ill conditioned. Therefore, the second step is to further centralize the singular values of each submodel by using a matrix balance method. Afterward, all submodels are well conditioned and obtain much higher observability indices compared with those of typical models. Simulation results indicate that significant improvements in the stability of identification results and the identifiability of unknown parameters are acquired by using the new identification submodels. Experimental results indicate that the proposed calibration method increases the identification accuracy without incurring additional hardware setup costs to the typical calibration method.

Modelling the Prototype Repository

2018 ◽  
Vol 482 (1) ◽  
pp. 241-260 ◽  
Author(s):  
V. Tsitsopoulos ◽  
S. Baxter ◽  
D. Holton ◽  
J. Dodd ◽  
S. Williams ◽  
...  
Keyword(s):  
Numerical Modelling ◽  
Host Rock ◽  
Hard Rock ◽  
Task Force ◽  
Fractured Rock ◽  
Fracture Network ◽  
Atmospheric Conditions ◽  
Predictive Capability ◽  
Rock Laboratory ◽  
Modelling Methodology

AbstractThe Prototype Repository (PR) tunnel is located at the Äspö Hard Rock Laboratory near Oskarshamn in the southeast of Sweden. In the PR tunnel, six full-sized deposition holes (8.37 m deep and 1.75 m in diameter) have been constructed. Each deposition hole is designed to mimic the Swedish reference system for the disposal of nuclear fuel, KBS-3V. The PR experiment is designed to provide a full-scale simulation of the emplacement of heat-generating waste. There are three phases to the experiment: (1) the open tunnel phase following construction, where both the tunnel and deposition holes are open to atmospheric conditions; (2) the emplacement of canisters (containing heaters), backfill and seal in the first section of the tunnel; and (3) the emplacement of canisters, backfill and seal in the second section of the tunnel. This work describes the numerical modelling, performed as part of the engineered barrier systems (EBS) Task Force, to understand the thermo-hydraulic (TH) evolution of the PR experiment and to provide a better understanding of the interaction between the fractured rock and bentonite surrounding the canister at the scale of a single deposition tunnel. A coupled integrated TH model for predicting the wetting and the temperature of bentonite emplaced in fractured rock was developed, accounting for the heterogeneity of the fractured rock. In this model, geometrical uncertainties of fracture locations are modelled by using several stochastic realizations of the fracture network. The modelling methodology utilized information available at early stages of site characterization and included site statistics for fracture occurrence and properties, as well as proposed installation properties of the bentonite. The adopted approach provides an evaluation of the predictive capability of models, it gives an insight of the uncertainties to data and demonstrates that a simplified equivalent homogeneous description of the fractured host rock is insufficient to represent the bentonite resaturation.

scholarly journals Predicting the Pressure Drops across Cellulose Acetate Filters

1986 ◽  
Vol 13 (4) ◽  
pp. 157-168
Author(s):  
RW Dwyer
Keyword(s):  
Fluid Flow ◽  
Theoretical Model ◽  
Pressure Drop ◽  
Cellulose Acetate ◽  
Flow Rate ◽  
Fluid Flow Rate ◽  
Cross Sectional ◽  
Cigarette Filter ◽  
Pressure Drops

AbstractA theoretical model of the pressure drop across a fibrous cigarette filter is derived. The pressure drop is expressed as a function of the filter dimensions, the fiber tow characteristics, the filter weight, the fluid flow rate, and a filter fiber factor. The fiber factor is affected by the distribution of the fibers within the filter, the relative orientations of the fibers, and their cross-sectional shapes. The model allows one to accurately calculate the influences of these variables on the filter pressure drop. Additionally, it can be used to predict capability curves and select an optimum cellulose acetate tow for a given filter pressure drop.

scholarly journals Time coordination of standalone measurement instruments by synchronized triggering

ACTA IMEKO ◽  
2015 ◽  
Vol 4 (3) ◽  
pp. 23 ◽  
Author(s):  
Francesco Lamonaca ◽  
Domenico Luca Carnì ◽  
Domenico Grimaldi
Keyword(s):  
Delay Line ◽  
Experimental Tests ◽  
Measurement Procedure ◽  
Phase Delay ◽  
Clock Frequency ◽  
Measurement Instruments ◽  
Delay Compensation ◽  
Clock Period ◽  
Correct Operation ◽  
Synchronization Accuracy

<p>A Hardware Interface (HI) to synchronize the operations of standalone Measurement Instruments (MIs) in the absence of networking has been proposed in the recent literature. The synchronization accuracy achieved is one period of the clock equipping the HI. To improve the synchronization accuracy two solutions can be argued on the basis of the mathematical model of the delay between HIs. The first involves increasing the clock frequency; the second concerns the compensation of the phase delay between HI clocks. In this paper the second solution is adopted in order to: (i) reduce the energy consumption, and (ii) not increase the complexity of the hardware architecture. The phase delay compensation is obtained by introducing a programmable delay line after the HI clocks. The phase delay evaluation and the successive tuning of the delay line are performed in the synchronization phase of the HIs. Once synchronized, each HI is moved to the standalone MI to trigger it according to the common sense of time. During the execution of the measurement procedure, networking is not necessary. Experimental tests validate the correct operation of the upgraded HI architecture and indicate that the achievable synchronization accuracy is a low percentage of the HI clock period.</p>

Experimental Study on Lean Blowout Limits of Turbulent Premixed Hydrogen/Ammonia/Air Mixtures

2021 ◽  
Author(s):  
Andreas Goldmann ◽  
Friedrich Dinkelacker
Keyword(s):  
Gas Turbines ◽  
Measurement Procedure ◽  
Liquid Fuels ◽  
Special Focus ◽  
Atmospheric Conditions ◽  
Ammonia Content ◽  
Lean Blowout ◽  
Combustion Properties ◽  
The Stability ◽  
Stability Limits

Abstract As the demand for greenhouse gas neutral transportation and power generation solutions is growing, alternative carbon-free fuel such as hydrogen (H2) and ammonia (NH3) are gaining more attention. Mixtures of both fuels allow the adjustment of combustion properties. With future fuels also the vision of very clean combustion can be taken into the focus, being for instance based on lean premixed and for liquid fuels prevaporized combustion for gas turbines. For the utilization of such concepts, however, flame stability is essential. In this study the upper stability limits, i.e. lean blowout of turbulent hydrogen/ammonia/air flames, is experimentally investigated in a generic non-swirl premixed burner at atmospheric conditions. Special focus is laid on a measurement setup with fully automatized measurement procedure, to reach the stability limits, as these limits tend to depend for instance on the approach speed towards the limit. The ammonia content was varied from 0 vol% to 50 vol% in 10 vol% steps with the rest being hydrogen, for a broad range of fuel-air-equivalence ratios. The lean blowout limit is increasing almost linearly with increasing fuel-air-equivalence ratios, whereas with increasing ammonia content the limit is decreasing. Furthermore, a model for the lean blowout limits were derived, which is able to predict the acquired experimental data with high accuracy.

Hydrogen Enriched Combustion Testing of SIEMENS Industrial SGT-400 at Atmospheric Conditions

2014 ◽  
Author(s):  
Kam-Kei Lam ◽  
Philipp Geipel ◽  
Jenny Larfeldt
Keyword(s):  
Pressure Drop ◽  
Natural Gas ◽  
High Speed ◽  
Flame Temperature ◽  
Stable Operation ◽  
Nox Emissions ◽  
Atmospheric Conditions ◽  
Reference Velocity ◽  
Operation Conditions ◽  
Combustion Behaviors

In order to further extend the turbine fuel flex capability, a test under atmospheric conditions of a full-scale SGT-400 burner was performed to study the combustion behavior when operating on hydrogen enriched natural gas. A high speed camera was installed in the rig to investigate the flame dynamics on different operation conditions. NOx emissions were measured for all presented conditions. The combustion system was instrumented with thermocouples on all the key locations to allow flame position monitoring and to avoid flame attachment on the hardware. Further measurements included static pressure probes to monitor combustor pressure drop. The test was conducted in a systematic matrix format to include the most important combustion parameters in order to identify their individual effects on the combustion behaviors. The quantity of hydrogen in natural gas, fuel split, air preheat temperature, air reference velocity and flame temperature were the combustion related variables studied in the presented test campaign. The volumetric hydrogen quantity could be increased to 30% maintaining stable operation for all measured conditions. Higher hydrogen contents up to 80 vol-% were reached without flash back tendency. A glowing spark igniter prevented testing at even higher hydrogen contents. Hydrogen enriched gas showed higher NOx emissions and improved blowout limit. Hydrogen blending in the fuel also reduced the combustor pressure drop, lowered the prechamber temperature and raised the pilot tip temperature.

A Experimental Study of Condensation Heat Transfer and Pressure Drop in a Single High Aspect Ratio Micro-Channel for Refrigerant R134a

2006 ◽  
Author(s):  
Sourav Chowdhury ◽  
Ebrahim Al-Hajri ◽  
Serguei Dessiatoun ◽  
Amir Shooshtari ◽  
Michael Ohadi
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Pressure Drop ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Small Diameter ◽  
Hydraulic Diameter ◽  
Condensation Heat Transfer ◽  
Small Scale ◽  
Measurement Instruments

Only recently, experimental data is available in open literature in condensation of various refrigerants in small hydraulic diameter microchannels. The phenomenon of two-phase flow and heat transfer mechanism in small diameter microchannels (< 1 mm) may be different than that in conventional tube sizes due to increasing dominance of several influencing parameters like surface tension, viscosity etc. This paper presents an on-going experimental study of condensation heat transfer and pressure drop of refrigerant R134a is a single high aspect ratio rectangular microchannel of hydraulic diameter 0.7 mm and aspect ratio 7:1. This data will help explore the condensation phenomenon in microchannels that is necessary in the design and development of small-scale heat exchangers and other compact cooling systems. The inlet vapor qualities between 20% and 80% and mass fluxes of 130 and 200 kg/m2s have been studied at present. The microchannel outlet conditions are maintained at close to thermodynamic saturated liquid state through a careful experimental procedure. A unique process for fabrication of the microchannel involving milling and electroplating steps has been adopted to maintain the channel geometry close to design values. Measurement instruments are well-calibrated to ensure low system energy balance error, uncertainty and good repeatability of test data. The trends of data recorded are comparable to that found in recent literature on similar dimension tubes.

scholarly journals Measuring Software Test Verification for Complex Workpieces based on Virtual Gear Measuring Instrument

2017 ◽  
Vol 17 (4) ◽  
pp. 197-207 ◽  
Author(s):  
Peili Yin ◽  
Jianhua Wang ◽  
Chunxia Lu
Keyword(s):  
Measurement Procedure ◽  
Measuring System ◽  
Software Test ◽  
Profile Measurement ◽  
Measuring Instrument ◽  
Detection Model ◽  
Whole Process ◽  
Triangular Patch ◽  
Virtual Workpiece ◽  
Test Verification

AbstractValidity and correctness test verification of the measuring software has been a thorny issue hindering the development of Gear Measuring Instrument (GMI). The main reason is that the software itself is difficult to separate from the rest of the measurement system for independent evaluation. This paper presents a Virtual Gear Measuring Instrument (VGMI) to independently validate the measuring software. The triangular patch model with accurately controlled precision was taken as the virtual workpiece and a universal collision detection model was established. The whole process simulation of workpiece measurement is implemented by VGMI replacing GMI and the measuring software is tested in the proposed virtual environment. Taking involute profile measurement procedure as an example, the validity of the software is evaluated based on the simulation results; meanwhile, experiments using the same measuring software are carried out on the involute master in a GMI. The experiment results indicate a consistency of tooth profile deviation and calibration results, thus verifying the accuracy of gear measuring system which includes the measurement procedures. It is shown that the VGMI presented can be applied in the validation of measuring software, providing a new ideal platform for testing of complex workpiece-measuring software without calibrated artifacts.

scholarly journals A fractal model for pressure drop through a cigarette filter

2020 ◽  
Vol 24 (4) ◽  
pp. 2653-2659 ◽  
Author(s):  
Zhanping Yang ◽  
Zhang Li ◽  
Dou Feng ◽  
Jie Li ◽  
Wenxuan Wan ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Cross Sections ◽  
Fractal Dimensions ◽  
Continuous Model ◽  
Fractal Model ◽  
Cigarette Filter ◽  
Factors Affecting ◽  
Filter Structure ◽  
Fractal Derivative ◽  
Main Factors

A fractal model for pressure drop through a cigarette filter is suggested, the fractal dimensions of both a single fiber and the filter?s cross-sections are calculated, which are two main factors affecting the pressure drop. The two-scale transform is made to convert the fractal derivative model on a smaller scale to an approximate continuous model on a larger scale, so that the model can be easily solved. An optimal filter structure is suggested for minimal pressure drop.

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