scholarly journals Bayesian Mass Averaging in Rigs and Engines

2022 ◽  
pp. 1-15
Author(s):  
Pranay Seshadri ◽  
Andrew Duncan ◽  
George Thorne
Keyword(s):  
Random Field ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Gaussian Random Field ◽  
Analytical Calculation ◽  
Sampling Procedure ◽  
Stagnation Pressure ◽  
Pressure Measurements

Abstract This paper introduces the Bayesian mass average and details its computation. Owing to the complexity of flow in an engine and the limited instrumentation and the precision of the sensor apparatus used, it is difficult to rigorously calculate mass averages. Building upon related work, this paper views any thermodynamic quantity's spatial variation at an axial plane in an engine (or a rig) as a Gaussian random field. In cases where the mass flow rate is constant in the circumferential direction but can be expressed via a polynomial or spline radially, this paper presents an analytical calculation of the Bayesian mass average. In cases where the mass flow rate itself can be expressed as a Gaussian random field, a sampling procedure is presented to calculate the Bayesian mass average. Examples of the calculation of the Bayesian mass average for temperature are presented, including with a real engine case study where velocity profiles are inferred from stagnation pressure measurements.

scholarly journals ANALYSIS OF EVAPORATOR EFFECTIVENESS ON 1/2 CYCLE REFRIGERATION SYSTEMS: A CASE STUDY ON LPG FUELED VEHICLES

2020 ◽  
Vol 82 (3) ◽  
Author(s):  
Muji Setiyo ◽  
Budi Waluyo ◽  
Nurkholis Hamidi
Keyword(s):  
Heat Transfer ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Exchange Process ◽  
Cooling Curve ◽  
Heat Exchange Process ◽  
Heat Transfer Capacity ◽  
The Ideal

The ½ cycle refrigeration system on LPG fueled vehicles has a significant cooling effect. However, the cooling is very dependent on the heat exchange process in the evaporator. Therefore, this paper analyses the deviation of the actual cooling curve from the ideal scenario carried out on a laboratory scale. The analytical method used is the calculation of the effectiveness of the evaporator, which compares the actual to the potential heat transfer capacity. The LPG flow rate was varied from 1-6 g/s, while the evaporation pressure ranged between 0.05, 0.10, and 0.15 MPa, which applied to compact type evaporators with dimensions of 262 ´ 200 mm, with a thickness of 65 mm. The research results confirm that the higher the LPG mass flow rate, the lower the heat transfer effectiveness. At the higher LPG mass flow rate, heat transfer occurs less optimally,  due to incomplete evaporation of LPG in the evaporator.

scholarly journals Simulation and Optimization of Municipal Solid Waste Combustion: A Case Study of a Fixed Bed Incinerator

2020 ◽  
pp. 5-19
Author(s):  
Arthur M. Omari ◽  
John P. John ◽  
Baraka Kichonge
Keyword(s):  
Municipal Solid Waste ◽  
Solid Waste ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Fixed Bed ◽  
Small Scale ◽  
Waste Incinerator ◽  
Simulation And Optimization

In this study, a Computational Fluid Dynamics (CFD) technique was used to develop a model for the simulation and flow conditions of the incinerator. The CFD technique are based on subdividing the volume of interest, i.e., the combustion chamber (or other parts of the plant) into a grid of elementary volumes. The relevant equations of conservation (mass, momentum, energy) are then applied to each of those elements, after defining all inputs, outputs and boundary conditions. The resulting system is then integrated from start to finish, after introducing momentum, mass and heat transfer. The objective of the study was to evaluate and optimize the performance of locally available incinerators in Tanzania. The small scale municipal solid waste incinerator modelling was done by using a fluent solver. The case study of the existing incinerator at a Bagamoyo hospital in Tanzania was used as a model and the obtained values were compared with simulated results and other publications for validation. The design optimization using CFD techniques to predict the performance of incinerator showed the deviation of input air by 14%, the mass flow rate by 26.5%, the mass fraction of carbon dioxide by 10.4% and slight deviation of nitrogen dioxide and carbon monoxide. The study suggested removing the ash during the incineration process by using a moving grate mechanism to minimize the possibility of formation of NOX. The study found the maximum mass flow rate capacity of incinerator to be 68kg/h with input air A1 as 0.03639 kg/s, input air A2 as 0.03046 kg/s and input air A3 as 0.03409 kg/s. The findings indicated that as capacity is scaled up, the available momentum declines relative to the dimensions of the furnace.

scholarly journals Numerical Simulation of Nozzle Flow Field with Secondary Injection Thrust Vector Control

2018 ◽  
Vol 179 ◽  
pp. 01003
Author(s):  
H.R. Noaman ◽  
Tang Hai Bin ◽  
Elsayed Khalil
Keyword(s):  
Vector Control ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Stagnation Pressure ◽  
Injection Angle ◽  
Thrust Vector Control ◽  
Thrust Vector ◽  
Shock Impingement ◽  
Secondary Injection

Numerical simulations are performed to characterize the secondary injection thrust vector control. For this objective the following measurements were taken: considering the flow to be compressible and turbulent using Realizable k-ε turbulence model accompanied by enhanced wall treatment, the comparison between the CFD results and the experimental results shows a very good agreement. Then a parametric study on injection mass flow rate (changing secondary stagnation pressure) with the same injection location and injection angle is done. The results stated that increasing the injectant mass flow rate lead to shock impingement from opposite wall at secondary stagnation pressure 1.4 of the primary stagnation pressure.

A Novel Technique for Measuring Stagnation Quantities and Gas Composition in High Temperature Flows

2010 ◽  
Author(s):  
Michela Massini ◽  
Robert J. Miller ◽  
Howard P. Hodson ◽  
Nick Collings
Keyword(s):  
High Temperature ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Gas Turbines ◽  
Stagnation Pressure ◽  
Temperature Measurements ◽  
Stagnation Temperature ◽  
Gas Composition ◽  
Reference Measurements

A new probe has been developed to measure the time averaged stagnation temperature, stagnation pressure and gas composition. This probe can be used in the high temperature regions of gas turbines, including downstream of the combustor and in the first stages of the high pressure turbines, as well as in other environments. The principal benefits of the new probe are that it overcomes the limitations of the standard methods that are used to measure temperature in high temperature environments and that it replaces three separate probes, for the three quantities mentioned above, with one single probe. A novel method of measuring temperature is used, which improves upon the accuracy of thermocouples and increases the temperature operating range. The probe consists of a choked nozzle placed in the hot flow at the point of interest. The working principle is based on the theory that for a choked nozzle, there is a fixed relationship between the stagnation quantities, the gas characteristics and the mass flow rate through the nozzle. The probe has an aspirated phase, where the gas composition and the mass flow rate are measured and a stagnated phase, where the stagnation pressure is measured. The stagnation temperature is determined from the above quantities. The operating principle has been proven valid through laboratory and rig tests. The probe has been successfully tested in a Rolls-Royce Viper engine up to 1000K and 2 bar and in a combustor rig up to 1800K and 4 bars. Measurements of stagnation temperature, stagnation pressure and gas compositions for these tests are presented in the paper and are compared with reference measurements. The accuracy of stagnation pressure and gas composition measurements is equal to the accuracy achievable with techniques that are commonly used in gas turbines. The estimated achievable accuracy of the aspirated probe in terms of temperature measurements is ±0.6%, i.e. ±10K at 1800K, which improves upon the accuracy of temperature measurements performed with standard thermocouples at the same temperatures, the uncertainty of which could be as high as ±2%.

Internal Losses and Flow Behavior of a Turbofan Stage at Windmill

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
Dilip Prasad ◽  
Wesley K. Lord
Keyword(s):  
Mass Flow Rate ◽  
Test Data ◽  
Mass Flow ◽  
Flow Rate ◽  
Rotational Speed ◽  
Pressure Loss ◽  
Flow Behavior ◽  
Stagnation Pressure ◽  
Simple Physical Model ◽  
Mach Numbers

The flow through a high-bypass ratio fan stage during engine-out conditions is investigated, with the objective of quantifying the internal losses when the rotor is at “windmill.” An analysis of altitude test data at various simulated flight Mach numbers shows that the fan rotational speed scales with the engine mass flow rate. Making use of the known values of the nozzle coefficients, we deduce the stagnation pressure loss of the fan stage, which rises significantly as the mass flow rate increases. In order to better understand this behavior, numerical simulations of the fan stage were carried out. The calculated losses agree well with the test data, and it is found that the bulk of the stagnation pressure loss occurs in the stator. A detailed examination of the flow field reveals that the relative flow leaves the rotor at very nearly the metal angle. Moreover, the rotational speed of the fan is such that the inboard sections of the fan blade add work to the flow, while the outboard sections extract work from it. The overall work is essentially zero so that the absolute swirl angle at the rotor exit is small, causing the stator to operate at a severely negative incidence. A gross separation ensues, and the resulting blockage of the stator passage accelerates the flow to high Mach numbers. The highly separated flow in the vane, together with the mixing of the large wakes behind it are responsible for the high losses in the vane. Based on the simulation results for the flow behavior, a simple physical model to estimate the windmill speed of the rotor is developed and is found to be in good agreement with the test data. The utility of this model is that it enables the development of a procedure to predict the internal drag at engine-out conditions, which is discussed.

scholarly journals A Methodology for Characterizing Representativeness Uncertainty in Performance Indicator Measurements of Power Generating Systems

2018 ◽  
Vol 3 (2) ◽  
Author(s):  
U. Otgonbaatar ◽  
E. Baglietto ◽  
Y. Caffari ◽  
N. E. Todreas ◽  
G. Lenci
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Cfd Simulation ◽  
Performance Indicator ◽  
Statistical Significance ◽  
Rate Measurement ◽  
Flow Rate Measurement ◽  
True Value

In this work, a general methodology and innovative framework to characterize and quantify representativeness uncertainty of performance indicator measurements of power generation systems is proposed. The representativeness uncertainty refers to the difference between a measurement value of a performance indicator quantity and its reference true value. It arises from the inherent variability of the quantity being measured. The main objectives of the methodology are to characterize and reduce the representativeness uncertainty by adopting numerical simulation in combination with experimental data and to improve the physical description of the measurement. The methodology is applied to an industrial case study for demonstration. The case study involves a computational fluid dynamics (CFD) simulation of an orifice plate-based mass flow rate measurement, using a commercially available package. Using the insight obtained from the CFD simulation, the representativeness uncertainty in mass flow rate measurement is quantified and the associated random uncertainties are comprehensively accounted for. Both parametric and nonparametric implementations of the methodology are illustrated. The case study also illustrates how the methodology is used to quantitatively test the level of statistical significance of the CFD simulation result after accounting for the relevant uncertainties.

scholarly journals Air Bag Momentum Force Including Aspiration

1995 ◽  
Vol 2 (2) ◽  
pp. 99-109
Author(s):  
Guy Nusholtz ◽  
Deguan Wang ◽  
E. Benjamin Wylie
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Sampling Procedure ◽  
Gas Jet ◽  
Cfd Model ◽  
System A ◽  
Jet Behavior ◽  
Series Of Experiments ◽  
Air Bag

A gas-jet momentum force drives the air bag into position during a crash. The magnitude of this force can change as a result of aspiration. To determine the potential magnitude of the effect on the momentum force and mass flow rate in an aspirated system, a series of experiments and simulations of those experiments was conducted. The simulation consists of a two-dimensional unsteady isentropic CFD model with special “infinite boundaries”. One of the difficulties in simulating the gas-jet behavior is determining the mass flow rate. To improve the reliability of the mass flow rate input to the simulation, a sampling procedure involving multiple tests was used, and an average of the tests was adopted.

scholarly journals The measuring system for air mass flow rate determination - difficult measuring conditions - case study

2021 ◽  
Vol 1741 ◽  
pp. 012028
Author(s):  
A Tomaszewski ◽  
T Przybyliński ◽  
M Lackowski ◽  
E Krzemiński ◽  
J Rogula ◽  
...  
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Measuring System ◽  
Air Mass
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