scholarly journals EXPERIMENTAL STUDY OF THE INLET FLOW IN A NON-PREMIXED COMBUSTION CHAMBER

2020 ◽  
Vol 19 (1) ◽  
pp. 72
Author(s):  
B. P. Trevisan ◽  
W. M. C. Dourado
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Experimental Study ◽  
Combustion Chamber ◽  
Equivalence Ratio ◽  
Premixed Combustion ◽  
Laser Doppler Velocimeter ◽  
Mean Flow ◽  
Inlet Flow ◽  
The Mean

The evaluation, validation and development of the models used in computation fluid dynamics requires the availability of experimental data for which the boundary conditions, especially the conditions of the inlet flow, are well defined. Laser diagnostics techniques provide experimental data used in computational fluid dynamics and are a powerful tool for measurements of the mean properties and fluctuations of the turbulent flow because they are non-intrusive methods, with high repetition rate and high spatial and temporal resolution. Therefore, in the present work an experimental study of the inlet flow (inert and combusting flows) in a non-premixed combustion chamber is presented. The velocity measurements were carried out using a laser Doppler velocimeter at the entrance region of the combustion chamber. An asymmetry on the mean flow and an increase on the total velocity fluctuations with the increase of the equivalence ratio was observed. The major effect on the increase of the equivalence ratio was a presence of a coherent movement on large scales associated to the flame brush dynamics.

CFD Investigation of the Effects of Different Diluents on the Emissions in a Swirl Stabilized Premixed Combustion System

2005 ◽  
Author(s):  
Ulf Engdar ◽  
Fredrik Hermann ◽  
Rolf Gabrielsson ◽  
Jens Klingmann
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Flow Field ◽  
Gas Turbines ◽  
Equivalence Ratio ◽  
Premixed Combustion ◽  
Inlet Temperature ◽  
Nox Emissions ◽  
Combustion System ◽  
Laminar Flamelet

Recently, new cycles for power generation, such as wet cycles and cycles for CO2 capture, have gained increasing interest. These new cycles use some sort of dilution in the air/fuel mixture, e.g. steam or CO2. Gas turbine cycles using LCV gases can also be said to fit this description. Almost all modern gas turbines use a lean premixed combustion system, since it combines low NOx emissions with high combustion efficiency. The main objective of this paper is to study the influence of different diluents on the NOx and CO emissions at different inlet temperature, equivalence ratio, pressure and mass flow. The studied combustor was a premixed swirl stabilized combustor with optical access and emission sampling equipment. The combustor uses Danish natural gas as its main fuel. Computational fluid dynamics (CFD) has been employed to perform the investigations. It is common knowledge that turbulence models based on the Buissinesq assumption are not generally capable of handling a highly swirling flow in a correct way. Therefore, a differential Reynolds stress model (DRSM) has been employed for modeling of the turbulence. The turbulent combustion has been modeled with the level-set flamelet library approach (FLA). In this approach a laminar flamelet is linked to turbulent flow field via a non-reacting scalar G and its variance. The laminar flamelet is modeled with separate code. This code solves the combustion development with a detailed reaction mechanism for a laminar, non-stretched and premixed one-dimensional flame. This is of great importance when emissions are to be predicted. All fluid dynamics computations were performed with the commercial CFD code Star-CD, version 3.20, where the FLA combustion model was implemented through Fortran based user subroutines. The computed flow field was validated against experimental data during non-reaction flow conditions. The computations showed good agreement with the experimental data. The computed CO and NOx emissions showed the same trends as the experimental data for the reacting case with an undiluted flame, when the equivalence ratio was altered. The computed emissions were used to build up an emission map for different dilutions during different operation conditions.

scholarly journals Experimental study on the mean flow characteristics of a supersonic multiple jet configuration

2021 ◽  
Vol 108 ◽  
pp. 106377
Author(s):  
Mohammed Faheem ◽  
Aqib Khan ◽  
Rakesh Kumar ◽  
Sher Afghan Khan ◽  
Waqar Asrar ◽  
...  
Keyword(s):  
Experimental Study ◽  
Flow Characteristics ◽  
Mean Flow ◽  
The Mean

scholarly journals Dynamics of the Blade Channel of an Inducer Under Cavitation-Induced Instabilities

2018 ◽  
Vol 141 (4) ◽  
Author(s):  
Angelo Pasini ◽  
Ruzbeh Hadavandi ◽  
Dario Valentini ◽  
Giovanni Pace ◽  
Luca d'Agostino
Keyword(s):  
Experimental Data ◽  
Spectral Analysis ◽  
Main Flow ◽  
Operating Conditions ◽  
Flow Instabilities ◽  
Mean Flow ◽  
Flow Oscillations ◽  
Rotating Frames ◽  
The Mean ◽  
High Head

A high-head three-bladed inducer has been equipped with pressure taps on the hub along the blade channels with the aim of more closely investigating the dynamics of cavitation-induced instabilities developing in the impeller flow. Spectral analysis of the pressure signals obtained from two sets of transducers mounted both in the stationary and rotating frames has allowed to characterize the nature, intensity, and interactions of the main flow instabilities detected in the experiments: subsynchronous rotating cavitation (RC), cavitation surge (CS), and a high-order axial surge oscillation. A dynamic model of the unsteady flow in the blade channels has been developed based on experimental data and on suitable descriptions of the mean flow and the oscillations of the cavitating volume. The model has been used for estimating at the inducer operating conditions of interest the intensity of the flow oscillations associated with the occurrence of the CS mode generated by RC in the inducer inlet.

Simulation of Pollutant Emissions in a Small-Sized Combustion Chamber With a Gas Fuel for Various Regime Modes

2019 ◽  
Author(s):  
Nikita I. Gurakov ◽  
Ivan A. Zubrilin ◽  
Ivan V. Chechet ◽  
Vladislav M. Anisimov ◽  
Sergey S. Matveev ◽  
...  
Keyword(s):  
Experimental Data ◽  
Combustion Chamber ◽  
Equivalence Ratio ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Combustion Products ◽  
Pollutant Emissions ◽  
Eddy Simulation ◽  
Flamelet Generated Manifold ◽  
Combustion Processes

Abstract The study shows the results of the emission simulation in a small-sized combustion chamber. The influence of temperature and equivalence ratio on CO and CxHy in the combustion chamber was investigated. Experiments and calculations were carried out for the following modes: temperature at the inlet of the combustion chamber Tinlet = 323 ... 523 K; equivalence ratio φ = 0.2 ... 0.33; normalized flow rate at the inlet of the combustion chamber λ = 0.1 ... 0.3. The simulation of combustion of natural gas was carried out. The studies were conducted using CFD software and experimental methods. Measurements of the combustion products composition were carried out by the method of sampling collection and subsequent chromatographic analysis. The flow and combustion processes were simulated in a three-dimensional steady formulation using the Reynolds-averaged Novier-Stokes equations (RANS) and in a transient formulation using the Large Eddy Simulation (LES) method. The combustion processes were simulated by Flamelet Generated Manifold model in conjunction with the probability density function method (PDF). In addition to the above methods, the method of the reactor network model (RNM) was used to simulate the emission. As a result, a comparison of the calculated and experimental data of concentrations values of combustion products and emissions indices averaged over the combustion chamber outlet was conducted. According to the results of the calculated-experimental study obtained: - the simulated concentrations values of the main combustion products such as CO2 and H2O qualitatively and quantitatively coincide with the experimental data (the discrepancy is less than 5%) for all three approaches — RANS, LES, RNM; - when modeling CO emissions, the discrepancy between the calculated emission indices obtained by the RANS and LES methods is greatly underestimated relative to the experimental data, whereas the values calculated by the RNM method deviate from the experiment by less than 10%; - mass concentration values of unburned hydrocarbons obtained by the RANS method are overestimated relative to the experimental values, while using the LES with RNM methods, the discrepancy does not exceed 10%.

Measurement of Impact Loads using a Laser Doppler Velocimeter

1990 ◽  
Vol 204 (1) ◽  
pp. 1-8 ◽  
Author(s):  
R S Birch ◽  
N Jones
Keyword(s):  
Experimental Study ◽  
Measuring Transducer ◽  
Research Field ◽  
Laser Doppler ◽  
Laser Doppler Velocimeter ◽  
Impact Loads ◽  
Peak Loads ◽  
Structural Impact ◽  
The Mean ◽  
Selection Of

The design and selection of transducers is an important consideration for the measurement of impact loads. This paper examines a load-measuring transducer based on a non-contact laser Doppler principle. An experimental study assesses the deformations and velocities obtained using a laser Doppler velocimeter and compares the mean and peak loads with those recorded by an accelerometer and a load cell. The paper concludes that this device is a valuable tool in the structural impact research field.

A vortex-street model of the flow in the similarity region of a two-dimensional free turbulent jet

1982 ◽  
Vol 123 ◽  
pp. 523-535 ◽  
Author(s):  
J. W. Oler ◽  
V. W. Goldschmidt
Keyword(s):  
Experimental Data ◽  
Reynolds Stress ◽  
Turbulent Jet ◽  
Vortex Street ◽  
Two Dimensional ◽  
Mean Flow ◽  
Mean Velocity ◽  
The Core ◽  
The Mean ◽  
Similarity Relationships

The mean-velocity profiles and entrainment rates in the similarity region of a two-dimensional jet are generated by a simple superposition of Rankine vortices arranged to represent a vortex street. The spacings between the vortex centres, their two-dimensional offsets from the centreline, as well as the core radii and circulation strengths, are all governed by similarity relationships and based upon experimental data.Major details of the mean flow field such as the axial and lateral mean-velocity components and the magnitude of the Reynolds stress are properly determined by the model. The sign of the Reynolds stress is, however, not properly predicted.

Measurements in Two-Dimensional Plumes in Crossflow

1989 ◽  
Vol 111 (2) ◽  
pp. 130-138 ◽  
Author(s):  
B. R. Ramaprian ◽  
H. Haniu
Keyword(s):  
Experimental Data ◽  
Short Distance ◽  
Two Dimensional ◽  
Mean Flow ◽  
Buoyant Jets ◽  
Laser Velocimetry ◽  
Buoyancy Forces ◽  
The Mean

The mean-flow and turbulent properties of two-dimensional buoyant jets discharged vertically upward into a crossflowing ambient have been measured in a hydraulic flume, using laser velocimetry and microresistance thermometry. The trajectory of the resulting inclined plume is found to be nearly straight, beyond a short distance from the source. The flow is essentially characterized by the presence of buoyancy forces along (s-direction) and perpendicular (n-direction) to the trajectory. While the s-component buoyancy tends to destabilize the flow and hence raise the overall level of turbulence in the flow, the n-component buoyancy tends to augment turbulence on the upper part of the flow and inhibit turbulence on the lower part. The experimental data are used to examine these effects quantitatively.

Differential stress modelling of turbulent flows in model reciprocating engines

1997 ◽  
Vol 211 (1) ◽  
pp. 59-77 ◽  
Author(s):  
C. J. Lea ◽  
A. P. Watkins
Keyword(s):  
Experimental Data ◽  
Turbulent Flows ◽  
Turbulence Intensity ◽  
Laser Doppler Anemometry ◽  
Turbulence Models ◽  
Apparent Difference ◽  
Mean Flow ◽  
Differential Stress ◽  
Reciprocating Engines ◽  
The Mean

A study is made here of the application of a differential stress model (DSM) of turbulence to flows in two model reciprocating engines. For the first time this study includes compressive effects. An assessment between DSM and k-ɛ results is made comparing with laser Doppler anemometry experimental data of the mean flow and turbulence intensity levels during intake and compression strokes. A well-established two-dimensional finite-volume computer code is employed. Two discretization schemes are used, namely the HYBRID scheme and the QUICK scheme. The latter is found to be essential if differentiation is to be made between the turbulence models. During the intake stroke the DSM results are, in general, similar to the k-ɛ results in comparison to the experimental data, except for the turbulence levels, which the DSM seriously underpredicts. This is in contrast to a parallel set of calculations of steady in-flow, which showed significant gains from using the DSM, particularly at the turbulence field level. The increased number of grid lines employed in those calculations contribute to this apparent difference between steady and unsteady flows, but cycle- to-cycle variations are more likely to be the primary cause, resulting in too high levels of turbulence intensity being measured. However, during the compression stroke the DSM returns vastly superior results to the k-ɛ model at both the mean flow and turbulence intensity levels. This is because the DSM generates an anisotropic shear stress field during the early stages of compression that suppresses the main vortical structure, in line with the experimental data.

scholarly journals Experimental study on combustion of CH4/NH3 fuel blends in an industrial furnace operated in flameless conditions

2020 ◽  
Vol 24 (6 Part A) ◽  
pp. 3625-3635
Author(s):  
Rafal Slefarski ◽  
Pawel Czyzewski ◽  
Michal Golebiewski
Keyword(s):  
Experimental Study ◽  
Combustion Chamber ◽  
Equivalence Ratio ◽  
Molar Fraction ◽  
Combustion Process ◽  
Steel Production ◽  
Methane Combustion ◽  
Efficient Technology ◽  
Flameless Combustion ◽  
Fuel Blends

This paper presents the results of an experimental study on the combustion process of methane mixed with NH3 in flameless mode. At a time of striving for CO2-free power, NH3 became a potential energy storage carrier fuel from renewable sources. Flameless combustion features low emissions and is a very efficient technology used in the power sector, as well as steel production, ceramics, etc. Industrial furnaces were tested in the context of pure methane combustion with an addition of NH3, up to 5%. Flameless combustion conditions were achieved with a regenerative gas burner system (high regenerative system). The burner consists of four ceramic regenerators allowing for continuous preheating of air, even up to 50 K lower than the temperature of the combustion chamber wall. Constant power of the introduced fuel was kept at 150 kW and the fuel-air equivalence ratio ranged from 0.75 to 0.95. The results have shown a growth of molar fraction of NO in flue gases when NH3 content in the fuel rose. The increase is more significant for the tests with a higher amount of oxygen in the combustion chamber (a lower fuel-air equivalence ratio). An addition of 5% of NH3 into the fuel caused an emission of NO at the levels of 113 ppmv and 462 ppmv (calculated to O2 = 0%), respectively for low and high fuel-air equivalence ratios.

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