Author: Mark E. NewfieldPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Optical Fiber Applications of Laser Absorption Diagnostics in Scramjet Combustors
Author: Mark E. NewfieldPractical Applications of Laser Absorption Spectroscopy for Aeroengine Testing
Author: Ian SchultzPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Reliable air-breathing hypersonic propulsion systems offer the potential to revolutionize aircraft performance in a variety of high-speed aerospace applications through substantial efficiency gains and hardware cost savings. Supersonic combustion ramjet (scramjet) engines are one such device that promise propulsion capabilities up to about Mach 10. However, before these devices are ever practically realized, considerable technical challenges must be overcome in combustor-inlet interaction, fuel-air mixing, and coupled turbulent flow/combustion modeling. The growing power of computational tools have accelerated the pace of solving these problems, but the accuracy of computational approaches can only be validated by rigorous experimental testing. Thus, there is a need for both facilities capable of creating conditions experienced during hypersonic flight, as well as diagnostics that can characterize the operation of those facilities and provide experimental data for the validation of computational models. Optical diagnostics such as laser absorption spectroscopy are capable of providing non-intrusive, in situ measurements of important flow-field parameters such as temperature, velocity, species concentrations, which makes them an invaluable resource to hypersonic aeroengine researchers. Absorption spectroscopy, in particular, has benefited from recent advances in laser and optics technology, allowing access to a variety of wavelengths corresponding to absorption transitions of important combustion species such as O2, H2O, and CO2. Moreover, these sensors only require compact, low-power laser sources and light can be delivered via fiber-optics, which enables the sensor to more easily integrate with test facility hardware. As a result, laser absorption spectroscopy has become a workhorse in experimental scramjet research, and has been applied in test facilities around the world. Building upon this prior work, here the design and results of several different spectroscopic sensors for facility characterization and distinct scramjet operation modes are presented. Both hydrogen-fueled and hydrocarbon-fueled scramjets are investigated in a variety of geometric configurations. These results comprise the largest data set of laser absorption spectroscopy measurements within scramjet combustors published to date, and are a valuable resource for computational researchers who wish to compare their models with experimental data. A primary drawback of laser absorption spectroscopy is that some techniques are sensitive to nonuniformity along the measurement line-of-sight. In highly three-dimensional flows such as within a scramjet combustor, this can prove to be a considerable hindrance. However, in the work here particular care has been taken to account for nonuniformity along the measurement path, and new techniques, including a new approach to wavelength-modulation spectroscopy data reduction, have been developed and applied to provide quantitatively accurate path-integrated measurements in the presence of nonuniformities. Additionally, novel applications of laser absorption spectroscopy are presented, including the use of absorption data to place an upper bound on the cavity residence time within a scramjet combustor, and a new sensor design for measuring air temperature in high-enthalpy facilities by tracking the formation of nitric oxide.
Near-Infrared Diode Laser Absorption Diagnostic for Temperature and Water Vapor in a Scramjet Combustor (Postprint).
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 13
Book Description
Tunable diode laser absorption measurements of gas temperature and water concentration were made at the exit of a model scramjet combustor fueled on JP-7. Multiplexed, fiber-coupled, near-infrared distributed feedback lasers were used to probe three water vapor absorption features in the 1.34 to 1.47 mum spectral region (2v1 and v1 + v3 overtone bands). Ratio thermometry was performed using direct absorption wavelength scans of isolated features at a 4-kHz repetition rate, as well as 2f wavelength modulation scans at a 2-kHz scan rate. Large signal-to-noise ratios demonstrate the ability of the optimally engineered optical hardware to reject beam steering and vibration noise. Successful measurements were made at full combustion conditions for a variety of fuel/air equivalence ratios and at eight vertical positions in the duct to investigate spatial uniformity. The use of three water vapor absorption features allowed for preliminary estimates of temperature distributions along the line of sight. The improved signal quality afforded by 2f measurements, in the case of weak absorption, demonstrates the utility of a scanned wavelength modulation strategy.
Advanced Laser Diagnostics of Compressible Flows
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
Advanced laser diagnostics have been developed to study the fundamentals of supersonic flows for scramjet applications. Filtered Rayleigh scattering and planar laser-induced fluorescence (PLIF) techniques were developed and applied for measuring temperature and species in reacting and nonreacting flows. Fundamental studies of a cavity flame-holder in reacting and nonreacting supersonic flows were conducted. Several cavity-configuration and fueling schemes were employed, and combustion performance was documented. Raman scattering was utilized to measure the time-averaged equivalence ratio of cavity fueling. OH-PLIF was used to mark the reaction zone of the combustion and aid the optimization of fueling. An isolator of rectangular cross section with adjustable divergence angles has been evaluated for different inlet Mach numbers. Shock structures and fluctuations of shock position were also identified at various Mach numbers, divergence angles, and pressure ratios. The potential application of a plasma torch as an alternative ignition source for the scramjet combustor was also investigated through experimental and CFD studies. Maintenance and upgrade of the test facility and support of testing were performed.
18th AIAA Aerospace Ground Testing Conference
Author: AIAA Fourth International Aerospace Planes Conference: 92-5073 - 92-5107
Author: Optical and Laser Diagnostics
Author: C ArcoumanisPublisher: CRC Press
ISBN: 9780750309585
Category : Technology & Engineering
Languages : en
Pages : 274
Book Description
From the automotive industry to blood flow monitoring, optical techniques and laser diagnostics are becoming integral parts in engineering and medical instrumentation. Written by leading global experts from industry, academic groups, and laboratories, this volume provides an international perspective on both existing applications and leading-edge research. With a focus on advanced engineering applications, the book discusses the application of techniques such as laser Doppler velocimetry, particle image velocimetry, and planar laser-induced fluorescence to automotive engines, burners, and gas turbines. It also covers the flow, sprays, and combustion in direct-injection gasoline engines as well as the fundamental structure of flames as revealed by complementary laser techniques. In addition, the book explores laser diagnostic techniques used in the biomedical field and reviews novel research on the use of fiber-optic sensor techniques for structural integrity and physical condition monitoring.
The Application of Laser Diagnostics, Light Emitting Diodes and Computer Modeling to the Characterization of Fuel-air Mixing in High Pressur Lean Premixed Combustion Systems
Author: James Wesley GirardLaser Diagnostics for Combustion Temperature and Species
Author: Alan C. EckbrethPublisher: CRC Press
ISBN: 1000124622
Category : Technology & Engineering
Languages : en
Pages : 630
Book Description
This book examines the variety of potential laser diagnostic techniques and presents a considerable theoretical foundation elucidating physics relevant to the laser diagnostics. It explains the Raman-based approaches for major species and temperature measurements.
Author: