Thermoacoustic Oscillations of Jet-A Fuel in Parallel Heated Flowpaths

2015 ◽  
Author(s):  
Steven A. Hunt
Keyword(s):  
Time Pressure ◽  
Pressure Oscillation ◽  
Acoustic Mode ◽  
Phase Lag ◽  
Fuel Flow Rate ◽  
Pressure Oscillations ◽  
Single Tube ◽  
Outlet Pressure ◽  
Fuel Flow ◽  
Thermoacoustic Oscillations

Pressure oscillations in supercritical Jet-A fuel flowing through four parallel, heated tubes connected to common manifolds have been observed in this study. Tests were performed with fuel inlet temperatures ranging from 200°F to 700°F, and fuel pressures ranging from 360–700 psi. Total fuel flow rate ranged from 7–37 lb/hr. Tubes were heated by blowing 850–870°F nitrogen over them. Acoustic-mode oscillations, typically ranging from 300–350 Hz, occurred only when a single tube was heated at a time. Pressure oscillation amplitudes ranged from 0.1–1.0 psi. Tube inlet and outlet pressure waveforms were separated by a phase lag that was a function of the manifold cross-passage diameter.

Thermoacoustic Oscillations in Multipath Heated Fuel Circuits

2017 ◽  
Vol 139 (9) ◽  
Author(s):  
Steven Hunt ◽  
Stephen Heister
Keyword(s):  
Characteristic Length ◽  
Pressure Oscillation ◽  
Acoustic Mode ◽  
Large Temperature ◽  
Phase Lag ◽  
Flow Conditions ◽  
Fuel Flow ◽  
Lower Frequency Mode ◽  
Thermoacoustic Oscillations ◽  
Fuel Tube

Pressure oscillations in supercritical jet-A fuel flowing through four parallel heated tubes connected to common manifolds have been observed in this study. Tests were performed with fuel inlet temperatures ranging from 70 °F to 700 °F, and fuel pressures ranging from 360 to 700 psi. Total fuel flow rate ranged from 5 to 55 lb/h. Tubes were heated by blowing 800–950 °F nitrogen over them. Acoustic-mode oscillations, typically ranging from 100 to 500 Hz, occurred only when a large temperature gradient was created inside the heated fuel tubes. Pressure oscillation amplitudes ranged from 0.1 to 1.0 psi. Oscillations at the inlet and outlet manifolds that were caused by a mode with the characteristic length of a single fuel tube were separated by a phase lag that was a function of the manifold cross-passage diameter. A lower frequency mode was also observed, which had a characteristic length based on the summed lengths of a single fuel tube and a single manifold passage. An acoustic simulation using the comsol acoustics module was performed to predict frequencies based on geometry and flow conditions of the experiment.

Spray Formation and Fuel Flow Rate at the Multi-Stage Injections Injected From the Swirl Nozzle

2003 ◽  
Author(s):  
Kokichi Sawada ◽  
Shinji Nakao ◽  
Tsuneaki Ishima ◽  
Tomio Obokata ◽  
Katsuyoshi Kawachi ◽  
...  
Keyword(s):  
Flow Rate ◽  
Gasoline Engine ◽  
Fuel Injection ◽  
Pressure Oscillation ◽  
Injection Rate ◽  
Fuel Flow Rate ◽  
Two Stage ◽  
Fuel Flow ◽  
Piv Measurement ◽  
Valve Opening

The structure, droplet characteristics and instantaneous fuel injection rate of two stage injection spray designed for direct injection gasoline engine were analyzed experimentally. A particle image velocimetry (PIV) to evaluate the instantaneous two-dimensional velocity field, a phase Doppler anemometer (PDA) and an instantaneous fuel flow rate meter based on a laser Doppler anemometer (LDA flow rate meter) were applied for the measurements. A swirl nozzle injector was used and injection conditions were 25 Hz of spray frequency, 2 ms and 1ms of the first and the second injection durations and 2.4, 3.3 and 9.1 ms of valve opening intervals. The initial jet of the second stage injection can overtook the main spray body of the first stage injection under the valve opening interval of 2.4 and 3.3 ms. The LDA flow rate meter made the injection rate measurement with sufficient accuracy in the two stage injection and showed the unstable second injection due to remaining pressure oscillation in the injection pipe. Both time averaged and time resolved PDA results were compared in the intermittent spray. The interaction between the first and the second sprays was also demonstrated in vector map obtained by the PIV measurement.

scholarly journals Investigation on Acoustic Properties of Thruster Chamber with Coaxial Injectors and Plenum Chamber

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Dekun Gao ◽  
Jianxiu Qin ◽  
Huiqiang Zhang
Keyword(s):  
Acoustic Pressure ◽  
Rocket Engine ◽  
Pressure Oscillation ◽  
Acoustic Mode ◽  
Acoustic Properties ◽  
Pressure Oscillations ◽  
Plenum Chamber ◽  
Model Chamber ◽  
Pressure Peak ◽  
Tuning Frequency

Based on the URANS equation, a numerical simulation is carried out for acoustic properties of the thruster chamber with coaxial injectors and plenum chamber in a liquid rocket engine. Pressure oscillations with multiacoustic modes are successfully excited in the chamber by using the constant volume bomb method. FFT analysis is applied to obtain the acoustic properties of eigenfrequencies, power amplitudes, and damping rates for each excited acoustic mode. Compared with the acoustic properties in the model chamber with and without an injector as well as with and without the plenum chamber, it can be found that the injector with one open end and one half-open end still can work as a quarter-wave resonator. The power amplitudes of the acoustic mode can be suppressed significantly when its eigenfrequency is close to the tuning frequency of the injector, which is achieved by Cutting down the pressure Peak and Raising up the pressure Trough (CPRT). Compared with the acoustic properties in the model chamber with and without the plenum chamber, it can be found that 1L acoustic pressure oscillation is inhibited completely by the plenum chamber and other acoustic pressure oscillations are also suppressed in a different extent. The injector and plenum chamber have a little effect on the eigenfrequencies and damping rate of each acoustic mode. For multimode pressure oscillation, it is better for tuning frequency of the injector closing to the lower eigenfrequency acoustic mode, which will be effective for suppression of these multiacoustic modes simultaneously.

Pressure Oscillations in a Combustor With Dual-Orifice Fuel Injection

1967 ◽  
Author(s):  
Rodney H. Hudson
Keyword(s):  
Gas Turbine ◽  
Flow Rate ◽  
Fuel Injection ◽  
Combustion Efficiency ◽  
Fuel Flow Rate ◽  
Spray Characteristics ◽  
Pressure Oscillations ◽  
Turbine Engine ◽  
Fuel Flow ◽  
Basic Engine

This paper presents a discussion of the investigation of a gas turbine engine to eliminate pressure oscillations which occurred in the combustor. The basic engine configuration and pertinent aspects of the combustor are described. The pressure oscillations were related to variations in the secondary fuel flow rate through the dual-orifice nozzles. The variations in fuel flow rate caused a fluctuation in nozzle spray characteristics which effected combustion efficiency.

Dynamic Simulation of a HRSG System for a Given Start-Up/Shut Down Curve

2011 ◽  
Author(s):  
Hun Cha ◽  
Yoo Seok Song ◽  
Kyu Jong Kim ◽  
Jung Rae Kim ◽  
Sung Min KIM
Keyword(s):  
Dynamic Analysis ◽  
Gas Turbine ◽  
Flow Rate ◽  
Exhaust Gas ◽  
Fuel Flow Rate ◽  
Fuel Flow ◽  
Start Up ◽  
Gas Turbine Exhaust ◽  
Main Steam ◽  
Duct Burner

An inappropriate design of HRSG (Heat Recovery Steam Generator) may lead to mechanical problems including the fatigue failure caused by rapid load change such as operating trip, start-up or shut down. The performance of HRSG with dynamic analysis should be investigated in case of start-up or shutdown. In this study, dynamic analysis for the HRSG system was carried out by commercial software. The HRSG system was modeled with HP, IP, LP evaporator, duct burner, superheater, reheater and economizer. The main variables for the analysis were the temperature and mass flow rate from gas turbine and fuel flow rate of duct burner for given start-up (cold/warm/hot) and shutdown curve. The results showed that the exhaust gas condition of gas turbine and fuel flow rate of duct burner were main factors controlling the performance of HRSG such as flow rate and temperature of main steam from final superheater and pressure of HP drum. The time delay at the change of steam temperature between gas turbine exhaust gas and HP steam was within 2 minutes at any analysis cases.

Model Analysis of Syngas Combustion and Emissions for a Micro Gas Turbine

2015 ◽  
Vol 137 (6) ◽  
Author(s):  
Chi-Rong Liu ◽  
Hsin-Yi Shih
Keyword(s):  
Gas Turbine ◽  
Flow Rate ◽  
Heat Input ◽  
Emission Characteristics ◽  
Nox Emissions ◽  
Fuel Flow Rate ◽  
Micro Gas Turbine ◽  
Fuel Flow ◽  
Temperature Distributions ◽  
Flame Structures

The purpose of this study is to investigate the combustion and emission characteristics of syngas fuels applied in a micro gas turbine, which is originally designed for a natural gas fired engine. The computation results were conducted by a numerical model, which consists of the three-dimension compressible k–ε model for turbulent flow and PPDF (presumed probability density function) model for combustion process. As the syngas is substituted for methane, the fuel flow rate and the total heat input to the combustor from the methane/syngas blended fuels are varied with syngas compositions and syngas substitution percentages. The computed results presented the syngas substitution effects on the combustion and emission characteristics at different syngas percentages (up to 90%) for three typical syngas compositions and the conditions where syngas applied at fixed fuel flow rate and at fixed heat input were examined. Results showed the flame structures varied with different syngas substitution percentages. The high temperature regions were dense and concentrated on the core of the primary zone for H2-rich syngas, and then shifted to the sides of the combustor when syngas percentages were high. The NOx emissions decreased with increasing syngas percentages, but NOx emissions are higher at higher hydrogen content at the same syngas percentage. The CO2 emissions decreased for 10% syngas substitution, but then increased as syngas percentage increased. Only using H2-rich syngas could produce less carbon dioxide. The detailed flame structures, temperature distributions, and gas emissions of the combustor were presented and compared. The exit temperature distributions and pattern factor (PF) were also discussed. Before syngas fuels are utilized as an alternative fuel for the micro gas turbine, further experimental testing is needed as the modeling results provide a guidance for the improved designs of the combustor.

scholarly journals A Method to Measure the Fuel Distribution and the Fuel Captured by V–Gutter Flameholder in High Speed Airstream

1985 ◽  
Author(s):  
Gu Shan-Jian ◽  
Yang Mao-Lin ◽  
Li Xiang-Yi
Keyword(s):  
Flow Rate ◽  
Experimental Error ◽  
High Speed ◽  
Fuel Flow Rate ◽  
Fuel Distribution ◽  
Fuel Flow ◽  
Sampling Condition ◽  
Detailed Determination

A method to measure the fuel distribution and the percentage of fuel flow rate captured by a V-gutter flameholder in a high speed airstream has been developed. The effects of configuration and size of the probe and temprature of the sample mixture in the probe on measurement have been investigated. The detailed determination of isokinetic sampling condition is described. The effects of V-gutter geometry on flowfield have been considered. The total experimental error is of the order ±5%.

System Level Analysis of Acoustically Forced Nonpremixed Swirling Flames

2014 ◽  
Vol 6 (3) ◽  
Author(s):  
Uyi Idahosa ◽  
Saptarshi Basu ◽  
Ankur Miglani
Keyword(s):  
Heat Release ◽  
Flow Rate ◽  
Ccd Camera ◽  
Time Dependent ◽  
Fuel Flow Rate ◽  
Fuel Flow ◽  
Flame Response ◽  
Rate Oscillations ◽  
Swirling Flames ◽  
Flame Sheet

This paper reports an experimental investigation of dynamic response of nonpremixed atmospheric swirling flames subjected to external, longitudinal acoustic excitation. Acoustic perturbations of varying frequencies (fp = 0–315 Hz) and velocity amplitudes (0.03 ≤ u′/Uavg ≤ 0.30) are imposed on the flames with various swirl intensities (S = 0.09 and 0.34). Flame dynamics at these swirl levels are studied for both constant and time-dependent fuel flow rate configurations. Heat release rates are quantified using a photomultiplier (PMT) and simultaneously imaged with a phase-locked CCD camera. The PMT and CCD camera are fitted with 430 nm ±10 nm band pass filters for CH* chemiluminescence intensity measurements. Flame transfer functions and continuous wavelet transforms (CWT) of heat release rate oscillations are used in order to understand the flame response at various burner swirl intensity and fuel flow rate settings. In addition, the natural modes of mixing and reaction processes are examined using the magnitude squared coherence analysis between major flame dynamics parameters. A low-pass filter characteristic is obtained with highly responsive flames below forcing frequencies of 200 Hz while the most significant flame response is observed at 105 Hz forcing mode. High strain rates induced in the flame sheet are observed to cause periodic extinction at localized regions of the flame sheet. Low swirl flames at lean fuel flow rates exhibit significant localized extinction and re-ignition of the flame sheet in the absence of acoustic forcing. However, pulsed flames exhibit increased resistance to straining due to the constrained inner recirculation zones (IRZ) resulting from acoustic perturbations that are transmitted by the co-flowing air. Wavelet spectra also show prominence of low frequency heat release rate oscillations for leaner (C2) flame configurations. For the time-dependent fuel flow rate flames, higher un-mixedness levels at lower swirl intensity is observed to induce periodic re-ignition as the flame approaches extinction. Increased swirl is observed to extend the time-to-extinction for both pulsed and unpulsed flame configurations under time-dependent fuel flow rate conditions.

scholarly journals A new generation of F1 race engines – hybrid power units

2016 ◽  
Vol 167 (4) ◽  
pp. 22-37 ◽  
Author(s):  
Zbigniew STĘPIEŃ
Keyword(s):  
Flow Rate ◽  
Regulatory Framework ◽  
Fuel Flow Rate ◽  
Maximum Performance ◽  
Engine Efficiency ◽  
Hybrid Power ◽  
Fuel Flow ◽  
New Generation ◽  
Technical Regulations

The paper aims at reviewing the evolution of the F1 engine technology and the associated regulatory framework governing the sport over the last 10 years. Technical regulations, in force since 2014, replaced the 2.4-liter V8 naturally aspirated engines with sophisticated hybrid units such as the 1.6-liter V6 turbocharged engines supported with energymanagement and recovery systems. Since 2014 the fundamental trend in the development of powertrains has been the advancement of their efficiency. Due to the fact that the fuel flow rate has been restricted, the maximum performance is now entirely dependent on the engine efficiency.

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