Generation characteristics of thermal NOx in a double-swirler annular combustor under various inlet conditions

Energy ◽  
2020 ◽  
Vol 200 ◽  
pp. 117487 ◽  
Author(s):  
Zaiguo Fu ◽  
Huanhuan Gao ◽  
Zhuoxiong Zeng ◽  
Jiang Liu ◽  
Qunzhi Zhu
Keyword(s):  
Annular Combustor ◽  
Inlet Conditions ◽  
Thermal Nox

Semi–Empirical Predictions and Correlations of NOx Emissions From Utility Combustion Turbines

1995 ◽  
Author(s):  
Donald M. Newburry ◽  
Arthur M. Mellor
Keyword(s):  
Natural Gas ◽  
A Priori ◽  
Fuel Oil ◽  
Pollutant Emissions ◽  
Nox Emissions ◽  
Time Model ◽  
Heterogeneous Effects ◽  
Inlet Conditions ◽  
Thermal Nox ◽  
Semi Empirical

Semi–empirical equations model the dominant subprocesses involved in pollutant emissions by assigning specific times to the fuel evaporation, chemistry, and turbulent mixing. They then employ linear ratios of these times with model constants established by correlating data from combustors with different geometries, inlet conditions, fuels, and fuel injectors to make a priori predictions. In this work, thermal NOx emissions from two heavy–duty, dual fuel (natural gas and fuel oil #2) diffusion flame combustors designated A and B operating without inert injection are first predicted, and then correlated using three existing semi–empirical approaches termed the Lefebvre (AHL) model, the Rizk–Mongia (RM) model, and the characteristic time model (CTM). Heterogeneous effects were found to be significant, as fuel droplet evaporation times were required to align the natural gas and fuel oil data. Only the RM model and CTM were employed to study this phenomenon. The CTM achieved the best overall prediction and correlation, as the data from both combustors fell within one standard deviation of the predicted line. The AHL and RM models were not able to account for the geometries of the two combustors. For Combustor A the CTM parameter correlated the data in a highly linear manner, as expected, but for Combustor B there was significant curvature. Using the CTM this was shown to be a residence time effect.

CFD Based Analysis of Burner Fuel Air Mixing Over a Range of Air Inlet and Fuel Pre-Heat Temperatures for a Siemens V94.3A Gas Turbine Burner

2006 ◽  
Author(s):  
O. R. Darbyshire ◽  
C. W. Wilson ◽  
A. Evans ◽  
S. B. M. Beck
Keyword(s):  
Gas Turbine ◽  
Computational Effort ◽  
Ambient Conditions ◽  
Fuel Gas ◽  
3 Dimensional ◽  
Continuity Equations ◽  
Air Inlet ◽  
Air Mixing ◽  
Inlet Conditions ◽  
Thermal Nox

The homogeneity of the fuel/air mix entering the combustion chamber of a gas turbine is known to be a factor in both the emissions performance (with poor mixing resulting in local hotspots and the formation of thermal NOx) and the generation of acoustic vibrations (humming). Obviously it is desirable to reduce both pollutants and unwanted acoustics as far as possible. The aim of this paper is to study the relationship between the local inlet conditions and the mixing of the fuel and air, specifically looking at the effects of fuel gas preheating and inlet air temperature on mixedness at the combustor inlet. A CFD model of the lean pre-mixed combustor for a Siemens v94.3A gas turbine was used to analyse the problem. The 3-dimensional model employs a structured mesh scheme and uses the symmetry of the burner to reduce computational effort. The model was solved using a 2nd order discretisation of the momentum and continuity equations along with the RNG k-ε turbulence model to provide closure. The boundary conditions for the model were taken from data obtained from in service measurements. Several runs were made using air inlet temperatures varying from −10°C to 30°C and gas inlet temperatures from 10°C to 450°C. The data obtained from the CFD simulations was processed to give an indication of the quality of the fuel/air mixing for each set of inlet conditions. This was then used to create a tool which can be used to determine the amount of gas pre-heat required to achieve the best possible mixing for a given set of ambient conditions. An estimation of the NOx produced at different conditions was derived from the mixing data. Analysis of the results showed that increasing the gas preheat produces an improvement in the mixing of the fuel and air in the burner. This improvement in mixing also resulted in a reduction in the estimated amount of NOx produced.

Investigation of the Unsteady Aerodynamics of an Annular Combustor Using PIV and LES

2008 ◽  
Author(s):  
Adrian Spencer ◽  
David Hollis ◽  
Sara Gashi
Keyword(s):  
Experimental Data ◽  
Boundary Conditions ◽  
Unsteady Aerodynamics ◽  
Predictive Ability ◽  
Fuel Injector ◽  
Predictive Tool ◽  
Annular Combustor ◽  
State Boundary ◽  
Inlet Conditions ◽  
Inflow Conditions

Experimental measurements have been carried out which have been used for specifying both boundary conditions of CFD predictions and for validation of the results. Combustor aerodynamics were therefore investigated in the same geometry, using LDA, PIV and LES. Three different LES simulations were performed in order to assess the flow field sensitivity to different boundary conditions. In the first run steady state boundary conditions are specified; in the second run, unsteady conditions at the injector exit and steady conditions in the annuli entry are specified; and in the third run unsteady boundary conditions at both injector exit and annuli entry are specified. A standard RANS simulation is also performed for comparison. The different simulations gave considerably different results. LES results with white noise scaled to give correct inlet turbulence intensities agree reasonably well with experimental data. With steady inflow conditions incorrect prediction of combustor aerodynamics resulted. Introduction of unsteady inflow conditions at the fuel injector exit plane were shown to have a significant effect on the flow interaction between the injector and the primary ports. LES is thus shown to be a good predictive tool for unsteady combustor flow fields. It is still questioned what level of fidelity is required in representing the inlet conditions to best use the predictive ability of LES. It offers significant improvement over standard RANS techniques but LES is more costly and requires detailed experimental data, used carefully, to correctly specify the inflow conditions.

Influence of Inlet Conditions on Flow and Combustion Characteristics of a Model Annular Combustor

1994 ◽  
Author(s):  
F. Baron ◽  
M. Kanniche ◽  
N. Mechitoua
Keyword(s):  
Gas Turbine ◽  
Mixing Rate ◽  
Air Jets ◽  
Air Temperatures ◽  
Co Concentration ◽  
Annular Combustor ◽  
Inlet Conditions ◽  
Β Function ◽  
The One ◽  
Good Agreement

k-ε model coupled with chemical equilibrium hypothesis is applied to a sector of an annular gas turbine combustion chamber similar to the one used in small gas turbine engines. The β-function is used as probability-density-function (pdf) of the distribution of a mixing rate scalar. The computation results are compared with velocity, temperature and species concentration measurements with air-to-fuel ratio of 29 and two inlet air temperatures of 315 K and 515 K. The measurements are reported in the PhD thesis of Tse [2] and in Bicen et al. [1]. Computed velocity and temperature are in good agreement with measurements, except close to primary injection holes where the normal impacts of air jets with the bulk flow involve strong streamline curvature which cannot be well predicted by standard k-ε model. Computed species concentrations are in good agreement with measurements, except (as expected) for CO concentration which is overestimated. Since the kinetic of CO burn-up is limited, the overestimation of CO concentration is a consequence of the simplified chemical reaction step.

Aerodynamic Evaluation of Double Annular Combustion Systems

2002 ◽  
Author(s):  
Paul A. Denman
Keyword(s):  
Gas Turbines ◽  
Pollutant Emissions ◽  
Quality Data ◽  
Test Facility ◽  
Oxides Of Nitrogen ◽  
Combustion System ◽  
Modular Construction ◽  
Radial Depth ◽  
Annular Combustor ◽  
Inlet Conditions

Legislation controlling the permitted levels of pollutant emissions from aircraft gas turbines has been an increasingly important design driver for the combustion system for some time, particularly with respect to oxides of nitrogen. This has lead to many suggestions for radical departures from the geometry of the classical combustor configuration involving, for example, lean premixed module technology, or staging (axially or radially) of combustor pilot and main zones. The optimum operation of any combustor also requires, however, appropriate and efficient distribution of compressor delivery air to the various flametube features (fuel injectors, dilution ports, for cooling and for air bleed purposes). Radial staging, leading to double annular combustor configurations, poses a particularly difficult challenge. The radial depth of the combustor increases to a level where the external aerodynamics of the combustor involves large flow turning after the pre-diffuser. Careful design is then needed to achieve acceptable levels of loss coefficient in the outer annulus. If these aspects are not properly addressed then inadequate penetration and mixing in the combustor interior can result, rendering low emissions performance impossible. This paper will report on the design, instrumentation and operation of a fully annular isothermal test facility, which has been developed specifically to enable this important issue of external flow quality in double annular combustor systems to be assessed. Representative inlet conditions to the combustion system are generated using a single stage axial compressor; modular construction enables quick and inexpensive changes to components of the combustor (pre-diffuser, cowl shape, liner port locations and geometrical details). Computerised rig control and data acquisition allows the collection of large amounts of high quality data. In addition to the calculation of overall system performance, it is then possible to identify flow mechanisms and loss-producing features in various zones and suggest appropriate modifications.

Numerical Insight Into Flow and Thermal Patterns Within an Inlet Profile Generator Comparing to Experimental Results

2006 ◽  
Author(s):  
V. R. Kunze ◽  
M. Wolff ◽  
M. D. Barringer ◽  
K. A. Thole ◽  
M. D. Polanka
Keyword(s):  
Computational Study ◽  
Three Dimensional ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Benchmark Tests ◽  
Annular Combustor ◽  
Inlet Conditions ◽  
Air Force Base ◽  
Turbine Design ◽  
Insight Into

Historically the design of gas turbine engines have not considered the interaction between the combustor and turbine stages. High pressure turbine vane stages have been designed assuming inlet conditions consistent with a standard turbulent boundary layer profile. However, combustor exit flow entering the vane is known to be highly non-uniform in both the primary and secondary flow regimes. In order to develop higher performance, more efficient, longer life stages, turbine design must take into account combustor exit non-uniformities. The Turbine Research Facility (TRF) at Wright-Patterson Air Force Base has installed a non-reactive full scale annular combustor simulator or more accurately a turbine inlet profile generator to study combustor-vane interaction. Several benchmark tests have been performed on the profile generator consisting of a Taguchi type matrix wherein nine independent variables were adjusted. Supplementing the experimental research at the TRF, a steady state, unstructured, fully three-dimensional CFD analysis was performed. This paper will make comparisons between the CFD and experimental profiles generated by the simulator. Furthermore, the computational study will help to give an understanding of the aerodynamic and aerothermal environment within the generator that experimental instrumentation alone cannot.

Performance of an Annular Combustor Under Windmill Conditions During Stand-Alone and Engine Level Altitude Test

2017 ◽  
Author(s):  
Srinivasan Karuppannan ◽  
Dalton Maurya ◽  
Raju D. Navindgi ◽  
N. Muthuveerappan
Keyword(s):  
Mach Number ◽  
Experimental Test ◽  
Total Pressure ◽  
Development Stage ◽  
Flight Altitude ◽  
Number Range ◽  
Turbine Engine ◽  
Annular Combustor ◽  
Engine Compressor ◽  
Inlet Conditions

Relight envelope of the combustor needs to be experimentally generated and established during the design and development of an aero gas turbine engine. Usually, during development stage of engine, compressor characteristics are not readily available at such low speeds and hence, it becomes difficult to specify the combustor inlet conditions such as pressure, temperature and Mach number during the engine light up studies. This paper compares the experimental test data generated on an annular combustor for windmill conditions during stand-alone mode and engine level tests under simulated flight conditions. The stand-alone combustor trials were conducted for the range of total pressure and temperature relevant to the flight altitude and Mach number range. During the engine level tests, combustor relight tests were conducted under simulated conditions (ISA+15) for altitudes ranging from 5.5 km to 10 km, flight Mach numbers in the range of 0.45 to 0.80. In this paper, effect of altitude and flight Mach number on the windmill spool speed, combustor pressure and temperature are studied.

scholarly journals Assessment of Mini-Tablets Coating Uniformity as a Function of Fluid Bed Coater Inlet Conditions

Pharmaceutics ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 746
Author(s):  
Magdalena Turk ◽  
Rok Šibanc ◽  
Rok Dreu ◽  
Maja Frankiewicz ◽  
Małgorzata Sznitowska
Keyword(s):  
Coating Layer ◽  
Spectrophotometric Analysis ◽  
Material Distribution ◽  
Spray Chamber ◽  
Colorimetric Analysis ◽  
Swirl Generator ◽  
Coating Uniformity ◽  
Fluid Bed ◽  
Inlet Conditions

This study concerned the quality of mini-tablets’ coating uniformity obtained by either the bottom spray chamber with a classical Wurster distributor (CW) or a swirl distributor (SW). Mini-tablets with a diameter of 2.0, 2.5, and 3.0 mm were coated with hypromellose using two different inlet air distributors as well as inlet airflow rates (130 and 156 m3/h). Tartrazine was used as a colorant in the coating layer and the coating uniformity was assessed by spectrophotometric analysis of solutions obtained after disintegration of the mini-tablets (n = 100). Higher uniformity of coating material distribution among the mini-tablets was observed in the case of SW distributor, even for the biggest mini-tablets (d = 3.0 mm), with an RSD no larger than 5.0%. Additionally, coating thickness was evaluated by colorimetric analysis (n = 1000), using a scanner method, and expressed as a hue value. A high correlation (R = 0.993) between inter-tablet variability of hue and UV-Vis results was obtained. Mini-tablets were successfully coated in a fluid bed system using both a classical Wurster distributor as well as a swirl generator. However, regardless of the mini-tablets’ diameter, better film uniformity was achieved in the case of a distributor with a swirl generator.

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