Response of Soot Temperature to Unsteady Inlet Airflow Under Modulated Condition and Naturally Occurring Combustion Dynamics

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Michael Knadler ◽  
Arda Cakmakci ◽  
Jong Guen Lee
Keyword(s):  
Temperature Fluctuation ◽  
Jet Fuel ◽  
Soot Temperature ◽  
Measured Temperature ◽  
Combustion Dynamics ◽  
Flow Modulation ◽  
Naturally Occurring ◽  
Flame Emission ◽  
Order Of Magnitude ◽  
Modulation Level

The response of soot temperature to unsteady inlet airflow is characterized using pyrometry. The unsteady inlet airflow is achieved by either modulating inlet air or naturally occurring unstable flame, running on a jet fuel at fuel-rich conditions. The inlet air is modulated by a siren device running at frequencies between 150 and 250 Hz and up to 60% of modulation level (u'/um) is achieved. Also, the combustor can be run naturally unstable at the same inlet operating condition by changing the combustor length. For pyrometry, the emission from whole flame at 660 nm, 730 nm, and 800 nm is recorded and the three-color pyrometry is used to measure soot temperature. The effect of nonisothermal distribution of soot in flame on the measured temperature is also considered. The level of overall temperature fluctuation under inlet flow modulation (Trms/Tmean) is about an order of magnitude lower than that of flame emission fluctuation (Irms/Imean). Under naturally occurring instability, the measured soot temperature is in phase with the pressure measured in the combustor, indicating that the measured soot temperature can be used as a quantity related to combustion dynamics for fuel-rich sooty flames.

Response of Soot Temperature to Unsteady Inlet Airflow Under Modulated Condition and Naturally-Occurring Combustion Dynamics

2014 ◽  
Author(s):  
Michael Knadler ◽  
Arda Cakmakci ◽  
Jong Guen Lee
Keyword(s):  
Temperature Fluctuation ◽  
Jet Fuel ◽  
Soot Temperature ◽  
Measured Temperature ◽  
Combustion Dynamics ◽  
Flow Modulation ◽  
Naturally Occurring ◽  
Flame Emission ◽  
Order Of Magnitude ◽  
Modulation Level

The response of soot temperature to unsteady inlet airflow is characterized using pyrometry. The unsteady inlet airflow is achieved by either modulating inlet air or naturally-occurring unstable flame, running on a jet fuel at fuel-rich conditions. The inlet air is modulated by a siren device running at frequencies between 150 and 250 Hz and up to 60% of modulation level (u’/um) is achieved. Also, the combustor can be run naturally unstable at the same inlet operating condition by changing the combustor length. For the pyrometry, the emission from whole flame at 660 nm, 730 nm and 800 nm is recorded and the three-color pyrometry is used to measure soot temperature. The effect of non-isothermal distribution of soot in flame on the measured temperature is also considered. The level of overall temperature fluctuation under inlet flow modulation (Trms/Tmean) is about an order of magnitude lower than that of flame emission fluctuation (Irms/Imean). Under naturally occurring instability the measured soot temperature is in phase with the pressure measured in the combustor, indicating that the measured soot temperature can be used as a quantity related to combustion dynamics for fuel-rich sooty flames.

Electrical Properties of Orthorhombic Iron Disilicide

1998 ◽  
Vol 545 ◽  
Author(s):  
Jun-Ichi Tani ◽  
Hiroyasu Kido
Keyword(s):  
Electrical Properties ◽  
Solid Solutions ◽  
Hole Concentration ◽  
Band Model ◽  
Measured Temperature ◽  
Iron Disilicide ◽  
Temperature Range ◽  
Order Of Magnitude ◽  
Mn Doped ◽  
Two Band Model

AbstractIn order to clarify the electrical properties of Cr-doped β-FeSi2(Fe1-xCrxSi2) and Mn-doped β--FeSi2(Fel-yMnySi2), the Hall effect and electrical resistivity of Fe1-xCrxSi2(0.01 ≦ x ≦ 0.05) and Fel-yMnySi2(0.01 ≦ y ≦ 0.10) have been measured in the temperature range between 80 and 300 K. fhe solid solutions Fel-xCrxSi2and Fel-yMnySi2are p-type over the measured temperature range. The observed features of RH of these solid solutions are explained by using the two-band model with the existence of two acceptor levels. The hole concentration of Fe1-xCrxSi2at 300 K ranges from 8.9×1018cm−3for x=0.01 to 1.1×1020cm−3for x=0.05, which is one order of magnitude higher than that of Fel-yMnySi2.

scholarly journals Mass-correlated rotational Raman spectra with high resolution, broad bandwidth, and absolute frequency accuracy

2018 ◽  
Vol 115 (20) ◽  
pp. 5072-5076 ◽  
Author(s):  
Christian Schröter ◽  
Jong Chan Lee ◽  
Thomas Schultz
Keyword(s):  
Raman Spectra ◽  
Optical Excitation ◽  
Rotational Transition ◽  
Observation Time ◽  
Absolute Frequency ◽  
Naturally Occurring ◽  
Order Of Magnitude ◽  
Quantum Wave ◽  
External Clock ◽  
Time And Energy

We present mass-correlated rotational alignment spectroscopy, based on the optical excitation of a coherent rotational quantum wave and the observation of temporal wave interferences in a mass spectrometer. Combined electronic and opto-mechanical delays increased the observation time and energy resolution by an order of magnitude compared with preceding time-domain measurements. Rotational transition frequencies were referenced to an external clock for accurate absolute frequency measurements. Rotational Raman spectra for six naturally occurring carbon disulfide isotopologues were resolved with 3 MHz resolution over a spectral range of 500 GHz. Rotational constants were determined with single-kilohertz accuracy, competitive with state-of-the-art frequency domain measurements.

Spatio-Temporal Distribution of Soot Temperature for Flames Using Optical Pyrometry Under Unsteady Inlet Airflow Conditions

2016 ◽  
Author(s):  
Arda Cakmakci ◽  
Michael Knadler ◽  
Jong Guen Lee
Keyword(s):  
Temperature Fluctuation ◽  
High Speed ◽  
Flame Temperature ◽  
Temperature Response ◽  
Local Temperature ◽  
Soot Temperature ◽  
High Speed Camera ◽  
Unsteady Combustion ◽  
Inlet Velocity ◽  
Multi Wavelength

Two pyrometric tools for measuring soot temperature response in fuel-rich flames under unsteady inlet airflow conditions are developed. High-speed pyrometry using a high-speed color camera is used in producing soot temperature distributions, with its results compared with those of global soot temperature response measured using a multi-wavelength pyrometer. For the former, the pixel RGB values pertaining to respective bandwidths of red, green and blue filters are used to calculate temperature and for the latter, the emission from whole flame at 660 nm, 730 nm and 800 nm is used to measure temperature. The combustor, running on Jet-A fuel, achieves unsteady inlet airflow using a siren running at frequencies of 150 and 250 Hz and with modulation levels (RMS) 20–50% of mean velocity. Spatiotemporal response of flame temperature measured by the high speed camera is presented by phase-averaged with average subtracted images and by fast Fourier transform at the modulation frequencies of inlet velocity. Simultaneous measurement of combustor inlet air velocity and flame soot temperature using the multi-wavelength pyrometer is used in calculating the flame transfer function of flame temperature response to unsteady inlet airflow. The results of global temperature and temperature fluctuation from the 3-color pyrometer show qualitative agreement with the local temperature response measured by the high speed camera. Over the range of operating conditions employed, the overall flame temperature fluctuation increases linearly with respect to the inlet velocity fluctuation. The two-dimensional map of flame temperature under unsteady combustion determined using a high-speed digital color camera shows that the local temperature fluctuation during unsteady combustion occurs over relatively small region of flame and its level is greater (∼10–20%) than that of overall temperature fluctuation (∼1%).

Diffusion of Sr in Bi2Sr2Can–1CunO2n+4

1993 ◽  
Vol 8 (10) ◽  
pp. 2465-2470 ◽  
Author(s):  
Nan Chen ◽  
S.J. Rothman ◽  
J.L. Routbort
Keyword(s):  
Diffusion Equation ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Pressure Range ◽  
Tracer Diffusion ◽  
Concentration Profiles ◽  
Measured Temperature ◽  
Serial Sectioning ◽  
Measured Temperature Range ◽  
Order Of Magnitude

Tracer diffusion of 85Sr in polycrystalline Bi2Sr2Can-1CunO2n+4 has been investigated for n = 1, 2, and 3 in an oxygen atmosphere between 775 and 850 °C. A radiotracer serial-sectioning technique was used to measure the concentration profiles, which were fit to a solution of the diffusion equation to calculate the diffusivities. The activation energies were 403, 553, and 519 kJ/mole, for n = 1, 2, and 3, respectively. However, the absolute values of D for the various layered superconductors did not differ by more than an order of magnitude over the measured temperature range. The diffusivity of Sr at 800 °C for n = 1 or 2 over an oxygen partial pressure range of 103 to 105 Pa increased as the pressure decreased.

A New Pulsed Flow Modulation GC × GC–MS with Cold EI System and Its Application for Jet Fuel Analysis

2016 ◽  
Vol 79 (11-12) ◽  
pp. 741-754 ◽  
Author(s):  
Uri Keshet ◽  
Alexander B. Fialkov ◽  
Tal Alon ◽  
Aviv Amirav
Keyword(s):  
Jet Fuel ◽  
Flow Modulation ◽  
Pulsed Flow ◽  
Cold Ei ◽  
Pulsed Flow Modulation

Spectra Thermal Fatigue Tests Under Frequency Controlled Fluid Temperature Variation: Development of Test Equipment and Preliminary Tests

2004 ◽  
Author(s):  
Naoto Kasahara ◽  
Shinichi Hasebe ◽  
Sumio Kobaysashi ◽  
Masanori Ando ◽  
Nobuchika Kawasaki ◽  
...  
Keyword(s):  
Temperature Variation ◽  
Thermal Fatigue ◽  
Temperature Fluctuation ◽  
Evaluation Method ◽  
Mechanical Valve ◽  
Test Equipment ◽  
Frequency Effect ◽  
Measured Temperature ◽  
Fluid Temperature ◽  
Constant Flow Rate

High cycle thermal fatigue induced by fluid temperature fluctuation is one of the important issues in nuclear plants. JNC has proposed a fatigue evaluation method paying attention to temperature attenuation related with frequency of fluctuation. In order to clarify the frequency effect of fluid temperature fluctuation on the crack initiation and propagation, a sodium temperature controlled thermal fatigue test equipment (SPECTRA) was developed. This equipment is capable of preciously controlling sodium temperature variation under various frequencies with a constant flow rate. This performance was achieved by the control of electromagnetic pumps without mechanical valve operations. Specimens are long straight pipes where temperature fluctuation ranges gradually reduce from upstream to downstream. As preliminary tests, temperature measurement and fatigue experiments were conducted. Measured temperature was preciously controlled under various frequencies. Cracks were observed in upstream area of a specimen. From above results, capability of frequency controlled test by SPECTRA facility was confirmed.

Air Flow Modulation for Refined Control of the Combustion Dynamics Using a Novel Actuator

2011 ◽  
Author(s):  
Fabrice Giuliani ◽  
Andreas Lang ◽  
Klaus Johannes Gradl ◽  
Peter Siebenhofer ◽  
Johannes Fritzer
Keyword(s):  
Gas Turbines ◽  
Air Flow ◽  
Elevated Pressure ◽  
Combustion Instabilities ◽  
Combustion Dynamics ◽  
Flow Modulation ◽  
Sonic Jet ◽  
Two Factors ◽  
The Stability ◽  
The One

A specific actuator able to modulate the air feed of a gas a burner at a given frequency and amplitude is presented. The Combustion Department at the Institute for Thermal Turbomachinery and Machine Dynamics at the Graz University of Technology has experience on the study of combustion instabilities in gas turbines using a flow excitor. The stability of an industrial burner is tested at elevated pressure and temperature conditions in the frame of the NEWAC project. For practical matters of operation among which the possibility to induce progressively a perturbation when the flame conditions are all set, the need was expressed to design, construct and validate a flexible actuator able to set an air flow modulation at a given frequency and at a desired amplitude level, with the possibility during operation to let these two factors vary in a given range independently from each other. This device should operate within the 0–1 kHz range and 0–20% amplitude range at steady-state, during transients, or follow a specific time sequence. It should be robust and sustain elevated pressures. The objective is to bring a perturbation in the flow to which the combustor will respond, or not. For elevated levels of pulsation, it can simulate the presence of vortex-driven combustion instabilities. It can also act as a real-time actuator able to respond in frequency and in phase to actively damp a “natural” combustion instability. Other issues are a better and quicker mixing due to the enhanced turbulence level, and pushing forward the blow out limits at lean conditions with controlled injection dynamics. The basic construction is the one of a siren, with an elevated pressure side where the air is throttled, and a low pressure outlet where the resulting sonic jet is sheared by a rotating wheel. A mechanism allows to let vary the surface of interaction between the wheel and the jet. Two electro-motors driven by Labview set both frequency and amplitude levels. This contribution describes the actuator’s principles, design, operation range and the results of the characterisation campaign.

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