Measurement of Emissions Variability of a Large Turbofan Aero-Engine

1978 ◽  
Author(s):  
D. H. Lister ◽  
M. I. Wedlock

Emmission measurements of carbon monoxide (CO), hydrocarbons (HC), and oxides of nitrogen (NOx) have been carried out on 12 Pratt and Whitney JT9D-7 turbofan engines after overhaul, and the effect of ambient conditions and engine to engine variation has been examined. Semi-theoretical correction factors, based on combustor inlet conditions, have also been applied to the data and a reduction in data scatter of better than 50 percent has been demonstrated. Average EPAPs for CO, HC, and NOx, have been determined: these are 13.9, 5.9, and 5.3 and bear a close relationship to other published data. Tests using both a fully thermostatted (423 K) or an uncooled probe have shown no observable differences in the measured emission levels.

1978 ◽  
Vol 100 (4) ◽  
pp. 640-646 ◽  
Author(s):  
P. Donovan ◽  
T. Cackette

A set of factors which reduces the variability due to ambient conditions of the hydrocarbon, carbon monoxide, and oxides of nitrogen emission indices has been developed. These factors can be used to correct an emission index to reference day ambient conditions. The correction factors, which vary with engine rated pressure ratio for NOx and idle pressure ratio for HC and CO, can be applied to a wide range of current technology gas turbine engines. The factors are a function of only the combustor inlet temperature and ambient humidity.


Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 334
Author(s):  
Bo Zhao ◽  
Geng Chen ◽  
Zijiang Xiong ◽  
Linbo Qin ◽  
Wangsheng Chen ◽  
...  

Arsenic emission from coal combustion power plants has attracted increasing attention due to its high toxicity. In this study, it was found that there was a close relationship between the ash fusion temperature (AFT) and arsenic distribution based on the thermodynamic equilibrium calculation. In addition to the AFT, coal characteristics and combustion temperature also considerably affected the distribution and morphology of arsenic during coal combustion. Thus, an arsenic volatilization model based on the AFT, coal type, and combustion temperature during coal combustion was developed. To test the accuracy of the model, blending coal combustion experiments were carried out. The experimental results and published data proved that the developed arsenic volatilization model can accurately predict arsenic emission during co-combustion, and the errors of the predicted value for bituminous and lignite were 2.3–9.8%, with the exception of JingLong (JL) coal when combusted at 1500 °C.


Author(s):  
Peter Baldwin

Americans Are Patriotic And Nationalist, but not more than some Europeans (figure 173). Unsurprisingly, Germans are least proud of their nation, and rather unexpectedly and cheerily, the Portuguese—not the Americans—are most proud, with the Irish tied for second place. A 2007 survey reveals that a larger proportion of Italians consider their culture superior than any other nationalities surveyed, including the Americans. Another survey finds that only the Irish feel more uniformly proud to be of their nation. Proportionately more Austrians, Irish, French, and Danes claim they feel very close to their nation than do Americans. Americans are more likely than any Europeans to think that their country is better than most others. But proportionately more Portuguese, Danes, and Spaniards feel that the world would be improved if other people were like them. And any U.S. tendency to boosterism is tempered by the finding that a larger fraction of Americans admits that certain aspects of their country shame them than do the Germans, Austrians, Spanish, French, Danes, or Finns. No country more robustly projects its own nationalist aspirations in the products it sells abroad than the supposedly postnational Swedes. Swedish manufacturers, or at least their advertising agencies, seem convinced that the sheer fact of being Swedish is a selling point. Ikea’s walls are adorned with musings on the preternaturally close relationship between Swedes and nature that allegedly sets them apart from the rest of humanity, as are packets of Wasa crispbread. Asko’s slogan, “Made In Sweden,” is festooned prominently on its products. Though it does not necessarily inspire confidence that the company’s dishwashers are better than the competition, it certainly makes clear Asko’s national origins. Absolut Vodka’s tag—in uncharacteristically unidiomatic English—“Country of Sweden,” does much the same. Saab hawks its cars as “Born from Jets,” an unsubtle allusion to the company’s standing as a pillar of the Swedish military-industrial complex.


1978 ◽  
Vol 20 (83) ◽  
pp. 405-408 ◽  
Author(s):  
I. J. Smalley

Abstract In 1899 P. A. Tutkovskiy published a theory of loess formation which depended on the presence of large continental glaciers. Unfortunately there was no glacial requirement in the theories of Berg and Richthofen and these have survived better than that of Tutkovskiy with the result that the close relationship between glacial action and loess formation is sometimes overlooked.


Author(s):  
Xin Zhao ◽  
Oskar Thulin ◽  
Tomas Grönstedt

Although the benefits of intercooling for aero-engine applications have been realized and discussed in many publications, quantitative details are still relatively limited. In order to strengthen the understanding of aero-engine intercooling, detailed performance data on optimized intercooled (IC) turbofan engines are provided. Analysis is conducted using an exergy breakdown, i.e., quantifying the losses into a common currency by applying a combined use of the first and second law of thermodynamics. Optimal IC geared turbofan engines for a long range mission are established with computational fluid dynamics (CFD) based two-pass cross flow tubular intercooler correlations. By means of a separate variable nozzle, the amount of intercooler coolant air can be optimized to different flight conditions. Exergy analysis is used to assess how irreversibility is varying over the flight mission, allowing for a more clear explanation and interpretation of the benefits. The optimal IC geared turbofan engine provides a 4.5% fuel burn benefit over a non-IC geared reference engine. The optimum is constrained by the last stage compressor blade height. To further explore the potential of intercooling the constraint limiting the axial compressor last stage blade height is relaxed by introducing an axial radial high pressure compressor (HPC). The axial–radial high pressure ratio (PR) configuration allows for an ultrahigh overall PR (OPR). With an optimal top-of-climb (TOC) OPR of 140, the configuration provides a 5.3% fuel burn benefit over the geared reference engine. The irreversibilities of the intercooler are broken down into its components to analyze the difference between the ultrahigh OPR axial–radial configuration and the purely axial configuration. An intercooler conceptual design method is used to predict pressure loss heat transfer and weight for the different OPRs. Exergy analysis combined with results from the intercooler and engine conceptual design are used to support the conclusion that the optimal PR split exponent stays relatively independent of the overall engine PR.


Author(s):  
O. R. Darbyshire ◽  
C. W. Wilson ◽  
A. Evans ◽  
S. B. M. Beck

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.


Author(s):  
Carlos Arroyo Osso ◽  
T. Gunnar Johansson ◽  
Fredrik Wallin

In most designs of two-spool turbofan engines, intermediate turbine duct (ITD’s) are used to connect the high-pressure turbine (HPT) with the low-pressure turbine (LPT). Demands for more efficient engines with reduced emissions require more “aggressive ducts”, ducts which provide both a higher radial offset and a larger area ratio in the shortest possible length, while maintaining low pressure losses and avoiding non-uniformities in the outlet flow that might affect the performance of the downstream LPT. The work presented in this paper is part of a more comprehensive experimental and computational study of the flowfield and the heat transfer in an aggressive ITD. The main objectives of the study were to obtain an understanding of the mechanisms governing the heat transfer in ITD’s and to obtain high quality experimental data for the improvement of the CFD-based design tools. This paper consists of two parts. The first one, this one, presents and discusses the results of the experimental study. In the second part, a comparison between the experimental results and a numerical analysis is presented. The duct studied was a state-of-the-art “aggressive” design with nine thick non-turning structural struts. It was tested in a large-scale low-speed experimental facility with a single-stage HPT. In this paper measurements of the steady convective heat transfer coefficient (HTC) distribution on both endwalls and on the strut for the duct design inlet conditions are presented. The heat transfer measurement technique used is based on infrared-thermography. Part of the results of the flow measurements is also included.


Author(s):  
Simon Gövert ◽  
Federica Ferraro ◽  
Alexander Krumme ◽  
Clemens Buske ◽  
Marc Tegeler ◽  
...  

Abstract Reducing the uncertainties in the prediction of turbine inlet conditions is a crucial aspect to improve aero engine designs and further increase engine efficiencies. To meet constantly stricter emission regulations, lean burn combustion could play a key role for future engine designs. However, these combustion systems are characterized by significant swirl for flame stabilization and reduced cooling air mass flows. As a result, substantial spatial and transient variations of the turbine inlet conditions are encountered. To investigate the effect of the combustor on the high pressure turbine, a rotating cooled transonic high-pressure configuration has been designed and investigated experimentally at the DLR turbine test facility ‘NG-Turb’ in Göttingen, Germany. It is a rotating full annular 1.5 stage turbine configuration which is coupled to a combustor simulator. The combustor simulator is designed to create turbine inlet conditions which are hydrodynamically representative for a lean-burn aero engine. A detailed description of the test rig and its instrumentation as well as a discussion of the measurement results is presented in part I of this paper. Part II focuses on numerical modeling of the test rig to further extend the understanding of the measurement results. Integrated simulations of the configuration including combustor simulator and nozzle guide vanes are performed for leading edge and passage clocking position and the effect on the hot streak migration is discussed. The simulation and experimental results at the combustor-turbine interface are compared showing a good overall agreement. The relevant flow features are correctly predicted in the simulations, proving the suitability of the numerical model for application to integrated combustor-turbine interaction analysis.


2014 ◽  
Vol 23 (2) ◽  
pp. 173-181 ◽  
Author(s):  
Ann E. Perreau ◽  
Bryn Spejcher ◽  
Hua Ou ◽  
Richard Tyler

Purpose Although a number of questionnaires are available to assess hearing aid benefit and general hearing disability, relatively few investigate spatial hearing ability in more complex listening situations. The aim of this study was to document the performance of individuals with normal hearing using the Spatial Hearing Questionnaire (SHQ; Tyler, Perreau, & Ji, 2009) and to compare performance with published data from cochlear implant (CI) users. Method Fifty-one participants with normal hearing participated. All participants completed the 24-item SHQ. Also, a factor analysis and reliability tests were performed. Results Performance on the SHQ was high (87%) for the participants with normal hearing. Subjective ratings varied across different listening situations: Understanding speech in quiet (98%) was rated higher than sound localization (84%) and understanding speech in a background of noise (85%). Compared with previously published data (Tyler, Perreau, & Ji, 2009), listeners with normal hearing rated their spatial hearing ability significantly better than bilateral and unilateral CI users. Results confirmed that the SHQ is a reliable measure of spatial hearing ability for listeners with normal hearing. Conclusions Overall, results indicated that the SHQ is able to capture expected differences between individuals with normal hearing and CI users. These new data can be used as targets following the provision of hearing devices.


2017 ◽  
Vol 37 (04) ◽  
pp. 314-331 ◽  
Author(s):  
Johannes Hov ◽  
Tom Karlsen

AbstractThe close relationship between primary sclerosing cholangitis (PSC) and inflammatory bowel disease has inspired hypothetical models in which gut bacteria or bacterial products are key players in PSC pathogenesis. Several studies using high-throughput sequencing technology to characterize the gut microbiota in PSC have been published over the past years. They all report reduced diversity and significant shifts in the overall composition of the gut microbiota. However, it remains unclear as to whether the observed changes are primary or secondary to PSC development and further studies are needed to assess the biological implications of the findings. In the present article, we review the published data in perspective of similar studies in other diseases. We discuss aspects of methodology and study design that are relevant to interpretation of the data. Furthermore, we propose that interpretation and further assessments of findings are structured into conceptual compartments, and elaborate three such possible concepts relating to immune function (the “immunobiome”), host metabolism (the “endobiome”), and dietary and xenobiotic factors (the “xenobiome”) in PSC.


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