Diagnostics combustors

Laser Raman diagnostic teclmiques offer remote, nonintnisive, nonperturbing measurements with high spatial and temporal resolution [158], This is particularly advantageous in the area of combustion chemistry. Physical probes for temperature and concentration measurements can be debatable in many combustion systems, such as furnaces, internal combustors etc., since they may disturb the medium or, even worse, not withstand the hostile enviromnents [159]. Laser Raman techniques are employed since two of the dominant molecules associated with air-fed combustion are O2 and N2. Flomonuclear diatomic molecules unable to have a nuclear coordinate-dependent dipole moment caimot be diagnosed by infrared spectroscopy. Other combustion species include CFl, CO2, FI2O and FI2 [160]. These molecules are probed by Raman spectroscopy to detenuine the temperature profile and species concentration m various combustion processes. 

As a specific example to study the characteristics of the controller, the problem involving four modes of longitudinal oscillations is considered herein. The natural radian frequency of the fundamental mode, normalized with respect to 7ra/L, is taken to be unity. The nominal linear parameters Dni and Eni in Eq. (22.12) are taken from [1], representing a typical situation encountered in several practical combustion chambers. An integrated research project comprising laser-based experimental diagnostics and comprehensive numerical simulation is currently conducted to provide direct insight into the combustion dynamics in a laboratory dump combustor [27]. Included as part of the results are the system and actuator parameters under feedback actions, which can... 

Spatially Precise Laser Diagnostics for Practical Combustor Probing... 

In conclusion, the data accumulated during these experiments demonstrate that through the use of the CARS technique, combustion diagnostics can be performed in a large-scale practical combustor environment. Results also indicate the potential of CARS for the determination of temporally resolved temperature and species concentration. With the aid of such data, probability distribution functions can be obtained from which true time-averaged quantities may be determined. 

Eckbreth, A. C. "Spatially Precise Laser Diagnostics for Practical Combustor Probing," Presented at the 178th ACS National Meeting, Washington, D.C., September 10-14, 1979. 

Numerical simulations of compressible flows developing in both space and time with precise control of initial and boundary conditions are ideally suited in the quest to recognize and understand the local and global nature of the flow instabilities driving the combustor performance — which are the main focuses of this work. Numerical experiments can be used to isolate suspected fundamental mechanisms from others which might confuse issues. The extensive space/time diagnostics available based on the simulation database can be exploited to develop analytical and conceptual bases for improved modeling of the turbulent flame. 

Several studies [23-25] have shown the effect of the combustor inlet conditions on the predicted flame structure, liner temperature, and emissions. These boundary conditions include the axial, tangential, and radial velocities the turbulent kinetic energy and associated length scale. To characterize the flow field at the exit of the TARS, two approaches were adopted. First, advanced diagnostic, such as LDV (discussed above), was used to measure the flow field distribution at the exit of the swirler. The data collected are used for inlet boundary conditions for the LES and database for numerical model validation. Second, a RANS model was used to study mixing and turbulence parameters in the TARS swirler [6]. 

Section 1 is aimed at providing new fundamental and practical data for the development of efficient combustion control strategies. It includes development of novel diagnostic techniques to provide in situ meeisurement capabilities, novel computational tools to acquire deeper insight into the fundamental mechanisms, and interactions in two-phase flows and flames relevant to realistic combustors as well as their operating conditions. Further, detailed experimental and numerical studies of the physical and chemical phenomena in turbulent flames, and the novel passive and active control methodologies to control combustion instabili-... 

A combined experimental and computational research program investigating the role of partial premixing and swirl on pollutant and noise emissions from aeropropulsion gas-turbine engines is being performed by Frankel and his coworkers at Purdue University (Chapter 1). The diagnostics include PIV, microphone arrays, and gas analyzers in multiswirl and trapped-vortex combustors. 

Experimental testing under pressure of a test combustor, even if simplified and reduced, constitutes a difficult and expensive problem (safety, inspection, size, fluid supply, etc.), and it can be carried out by specialized organizations only. Industrial prototypes of GT combustors are tested in scale 1 1 during short (very expensive) trials updated, laser-based, diagnostic optical techniques are employed to squeeze as much experimental information as possible to be subsequently supplied to mathematical modelers for quantitative data processing. A detailed insight into the GT sector is out of the scope of the present book and it has been quoted only to remind researchers that testing may become extremely expensive and complicated. 

One useful way to determine the mutual connection between these quantities and properties and in what maimer they influence the sulfur capture process, is by the application of a mathematical sulfur retention model. Based on a parameter sensitivity analysis it is generally possible to focuss in on the main parameters that influence the sulfation process. In that way the model is used as a practical engineering tool for the analysis of combustors in design or operation (diagnostic or screening tool). However, the model may also be used as a predictive tool for the calculation of the required process operating conditions in an existing FBC facility. 

The test rig employed in this study consisted of a high-pressure cylindrical steel vessel with a length of 1.8 m and an internal diameter of 0.28 m (see Chap. 2). Visual inspection and accessibility of the reactor assembly was achieved via a 50 mm diameter quartz window at the rear flange of the vessel and two 350 mm long and 50 mm high quartz windows at the vessel sides. Experiments were performed in two different reactors. The first reactor was the optically accessible, channel-flow reactor presented in Sect. 2.1 therein, the use of in situ laser diagnostics (Sect. 2.2) allowed for the assessment of the catalytic reactivity of propane on platinum. The second reactor was a honeycomb subscale unit of the desired catalytic combustor (see Sect. 2.3), and was used for the evaluation of combustor performance characteristics. 

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