Autoignition Dynamics and Combustion of N-Dodecane Droplets Under Transcritical Conditions PDF Download
Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download Autoignition Dynamics and Combustion of N-Dodecane Droplets Under Transcritical Conditions PDF full book. Access full book title Autoignition Dynamics and Combustion of N-Dodecane Droplets Under Transcritical Conditions by Evan Noah Rose. Download full books in PDF and EPUB format.
Author: Evan Noah Rose Publisher: ISBN: Category : Liquid fuels Languages : en Pages : 140
Book Description
Understanding the spontaneous ignition and burning behavior of liquid fuels is critical to improving the performance of modern combustion devices. This work examines the effects of varying ambient temperature and pressure on the autoignition and burning characteristics of fiber-supported n-dodecane fuel droplets in normal gravity and in microgravity. Ambient temperatures and pressures were 500 to 1000 K and 1 to 25 atm, respectively, encompassing the transcritical region for n-dodecane. The results show the dynamics of ignition with the formation of a cool-flame front and a hot-flame front prior to the final establishment of a diffusion flame surrounding the droplet. These phenomena are observed for both normal gravity and microgravity environments. Measurement of two-stage ignition delay times shows qualitative agreement with previous research.
Author: Evan Noah Rose Publisher: ISBN: Category : Liquid fuels Languages : en Pages : 140
Book Description
Understanding the spontaneous ignition and burning behavior of liquid fuels is critical to improving the performance of modern combustion devices. This work examines the effects of varying ambient temperature and pressure on the autoignition and burning characteristics of fiber-supported n-dodecane fuel droplets in normal gravity and in microgravity. Ambient temperatures and pressures were 500 to 1000 K and 1 to 25 atm, respectively, encompassing the transcritical region for n-dodecane. The results show the dynamics of ignition with the formation of a cool-flame front and a hot-flame front prior to the final establishment of a diffusion flame surrounding the droplet. These phenomena are observed for both normal gravity and microgravity environments. Measurement of two-stage ignition delay times shows qualitative agreement with previous research.
Author: Saptarshi Basu Publisher: Springer ISBN: 9811074496 Category : Technology & Engineering Languages : en Pages : 433
Book Description
This book focuses on droplets and sprays relevant to combustion and propulsion applications. The book includes fundamental studies on the heating, evaporation and combustion of individual droplets and basic mechanisms of spray formation. The contents also extend to the latest analytical, numerical and experimental techniques for investigating the behavior of sprays in devices like combustion engines and gas turbines. In addition, the book explores several emerging areas like interactions between sprays and flames and the dynamic characteristics of spray combustion systems on the fundamental side, as well as the development of novel fuel injectors for specific devices on the application side. Given its breadth of coverage, the book will benefit researchers and professionals alike.
Author: Titus S. Chen Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Experimental measurements and model predictions of ignition delay times for single component and two-component liquid fuels are presented. The methodology used is the suspended-droplet/moving-furnace technique, in which a droplet of fuel is suspended from the tip of a thin quartz fibre. A preheated electric furnace moves towards and encompasses the droplet locality, producing a sudden rise in ambient temperature, and thus initiating the ignition process. The entire apparatus is enclosed in a pressure vessel and is remotely operated. Data were collected for pressures up to 18 atm absolute and in a temperature range of 773 K to 973 K. Fuels tested comprised n-paraffins (decane, dodecane, and hexadecane), aromatics (mesitylene, o-xylene, and isobutylbenzene) and a cycloparaffin (decalin), as well as selected binary combinations: n-decane/n-dodecane, n-dodecane/n-hexadecane, n-decane/decalin, n-decane/isobutylbenzene, n-decane/mesitylene, and n-decane/o-xylene. Paraffin measurements at low pressures and high temperature revealed a monotonic decrease in ignition times with increasing pressure. However, higher pressure ignitions at lower temperatures showed more complex behaviour by the measurement of two or "twinned" ignition times for the same pressure and temperature condition, indicating a change in reaction mechanism, possibly from one-stage to two-stage ignition. Aromatic fuels did not show "twinned" ignition time behaviour and responded with a slight increase in ignition times with increasing pressure, owing to a weaker reaction rate dependence on pressure. The cycloparaffin behaved analogously to the n-paraffin family. The behaviour of mixtures was largely controlled by the more volatile component. (Abstract shortened by UMI.).
Author: Giulio Borghesi Publisher: ISBN: Category : Languages : en Pages :
Book Description
This dissertation deals with the numerical investigation of the physics of sprays autoigniting at diesel engine conditions using Direct Numerical Simulations (DNS), and with the modelling of droplet related effects within the Conditional Moment Closure (CMC) method for turbulent non-premixed combustion. The dissertation can be split in four different sections, with the content of each being summarized below. The first part of the dissertation introduces the equations that govern the temporal and spatial evolution of a turbulent reacting flow, and provides an extensive review of the CMC method for both single and two-phase flows. The problem of modelling droplet related effects in the CMC transport equations is discussed in detail, and physically-sound models for the unclosed terms that appear in these equations and that are affected by the droplet presence are derived. The second part of the dissertation deals with the application of the CMC method to the numerical simulation of several n-heptane sprays igniting at conditions relevant to diesel engine combustion. Droplet-related terms in the CMC equations were closed with the models developed in the first part of the dissertation. For all conditions investigated, CMC could correctly capture the ignition, propagation and anchoring phases of the spray flame. Inclusion of droplet terms in the CMC equations had little influence on the numerical predictions, in line with the findings of other authors. The third part of the dissertation presents a DNS study on the autoignition of n-heptane sprays at high pressure / low temperature conditions. The analysis revealed that spray ignition occurs first in well-mixed locations with a specific value of the mixture fraction. Changes in the operating conditions (initial turbulence intensity of the background gas, global equivalence ratio in the spray region, initial droplet size distribution) affected spray ignition through changes in the mixture formation process. For each spray, a characteristic ignition delay time and a characteristic droplet evaporation time could be defined. The ratio between these time scales was suggested as a key parameter for controlling the ignition delay of the spray. The last part of the dissertation exploits the DNS simulations to perform an a priori analysis of the applicability of the CMC method to autoigniting sprays. The study revealed that standard models for the mixing quantities used in CMC provide poor approximations in two-phase flows, and are partially responsible for the poor prediction of the ignition delay time. It was also observed that first-order closure of the chemical source terms performs poorly during the onset of ignition, suggesting that second-order closures may be more appropriate for studying spray autoignition problems. The contribution of the work presented in this dissertation is to provides a detailed insight into the physics of spray autoignition at diesel engine conditions, to propose and derive original methods for incorporating droplet evaporation effects within CMC in a physically-sound manner, and to assess the applicability and shortcomings of the CMC method to autoigniting sprays.
Author: Evan Noah Rose
Author: Evan Noah Rose
Author: Saptarshi Basu
Author: Titus S. Chen
Author: Shaun Sabourin
Author: Lawrence John Bowerman
Author: Mun Young Choi
Author: Michael J. Pilling
Author: Giulio Borghesi
Author: Kyeong-Ook Lee
Author: