Semiempirical Analysis of Liquid Fuel Distribution Downstream of a Plain Orifice Injector Under Cross-Stream Air Flow

1982 ◽  
Vol 104 (4) ◽  
pp. 788-795 ◽  
Author(s):  
Ming-hua Cao ◽  
Hong-kun Jiang ◽  
Ju-shan Chin
Keyword(s):  
Ambient Temperature ◽  
Test Data ◽  
High Velocity ◽  
Liquid Fuel ◽  
Air Flow ◽  
Liquid Sheet ◽  
Flow Path ◽  
Preliminary Design ◽  
Fuel Injector ◽  
Fuel Distribution

An improved semiempirical analysis is presented for the liquid fuel distribution downstream of a plain orifice fuel injector under a cross-stream air flow of uniform high velocity and constant ambient temperature. The analysis is based on a simplified “flat-fan spray” model (ε–ψ model). A ε–ψ model is proposed which assumes that the fuel injected through the orifice forms a flat-fan liquid sheet with an average fan angle 2ψ0. Once the droplets have been formed, the trajectory of individual droplets determines the fuel distribution downstream. The validity of the analysis is confirmed by comparison of calculations based on the ε–ψ model and test data obtained from fuel distribution experiments under cross-stream air flow of ambient temperature. The agreement is shown to be very good. The semiempirical analysis presented offers a very useful approach in the preliminary design of the fan air flow path portion of turbofan afterburners.

scholarly journals Semi-Empirical Analysis of Liquid Fuel Distribution Downstream of a Plain Orifice Injector Under Cross-Stream Air Flow

1982 ◽  
Author(s):  
Cao Ming-hua ◽  
Jiang Hong-kun ◽  
Chin Ju-shan
Keyword(s):  
Ambient Temperature ◽  
Empirical Analysis ◽  
High Velocity ◽  
Liquid Fuel ◽  
Air Flow ◽  
Liquid Sheet ◽  
Preliminary Design ◽  
Fuel Injector ◽  
Fuel Distribution ◽  
Semi Empirical

An improved semi-empirical analysis is presented for the liquid fuel distribution downstream of a plain orifice fuel injector under cross-stream airflow of uniform high velocity and constant ambient temperature. The analysis is based on a simplified “flat-fan spray” model (ε – ψ model). The ε – ψ model is proposed which assumes that the fuel injected through the orifice forms a flat-fan liquid sheet with an average fan angle 2 ψ0. Once the droplets have been formed, the trajectory of individual droplets determines the fuel distribution downstream. The validity of the analysis is confirmed by comparison of calculations based on the ε – ψ model and test data obtained from fuel distribution experiments under cross-stream air flow of ambient temperature. The agreement is shown to be very good. The semi-empirical analysis presented offers a very useful approach in the preliminary design of the fan air flow path portion of turbo-fan after-burners.

Modeling of Gas Turbine Fuel Nozzle Spray

1997 ◽  
Vol 119 (1) ◽  
pp. 34-44 ◽  
Author(s):  
N. K. Rizk ◽  
J. S. Chin ◽  
M. K. Razdan
Keyword(s):  
Gas Turbine ◽  
Fuel Injection ◽  
Near Field ◽  
Continuous Phase ◽  
Liquid Sheet ◽  
Vapor Concentration ◽  
Fuel Vapor ◽  
Fuel Injector ◽  
Gas Temperature ◽  
Sheet Breakup

Satisfactory performance of the gas turbine combustor relies on the careful design of various components, particularly the fuel injector. It is, therefore, essential to establish a fundamental basis for fuel injection modeling that involves various atomization processes. A two-dimensional fuel injection model has been formulated to simulate the airflow within and downstream of the atomizer and address the formation and breakup of the liquid sheet formed at the atomizer exit. The sheet breakup under the effects of airblast, fuel pressure, or the combined atomization mode of the airassist type is considered in the calculation. The model accounts for secondary breakup of drops and the stochastic Lagrangian treatment of spray. The calculation of spray evaporation addresses both droplet heat-up and steady-state mechanisms, and fuel vapor concentration is based on the partial pressure concept. An enhanced evaporation model has been developed that accounts for multicomponent, finite mass diffusivity and conductivity effects, and addresses near-critical evaporation. The presents investigation involved predictions of flow and spray characteristics of two distinctively different fuel atomizers under both nonreacting and reacting conditions. The predictions of the continuous phase velocity components and the spray mean drop sizes agree well with the detailed measurements obtained for the two atomizers, which indicates the model accounts for key aspects of atomization. The model also provides insight into ligament formation and breakup at the atomizer exit and the initial drop sizes formed in the atomizer near field region where measurements are difficult to obtain. The calculations of the reacting spray show the fuel-rich region occupied most of the spray volume with two-peak radial gas temperature profiles. The results also provided local concentrations of unburned hydrocarbon (UHC) and carbon monoxide (CO) in atomizer flowfield, information that could support the effort to reduce emission levels of gas turbine combustors.

Forced ignition of dispersions of liquid fuel in turbulent air flow

2017 ◽  
Author(s):  
Pedro M. de Oliveira ◽  
Epaminondas Mastorakos ◽  
Patton M. Allison
Keyword(s):  
Liquid Fuel ◽  
Air Flow ◽  
Turbulent Air Flow

scholarly journals A Comprehensive Model to Predict Simplex Atomizer Performance

1998 ◽  
Author(s):  
Y. Liao ◽  
A. T. Sakman ◽  
S. M. Jeng ◽  
M. A. Jog ◽  
M. Benjamin
Keyword(s):  
Stability Analysis ◽  
Film Thickness ◽  
Linear Stability ◽  
Linear Stability Analysis ◽  
Liquid Fuel ◽  
Density Ratio ◽  
Liquid Sheet ◽  
Unstable Wave ◽  
Liquid Sheets ◽  
Breakup Model

The performance of liquid fuel atomizer has direct effects on combustion efficiency, pollutant emission and stability. Pressure swirl atomizer, or simplex atomizer, is widely used in liquid fuel combustion devices in aircraft and power generation industry. A computational, experimental, and theoretical study is conducted to predict its performance. The Arbitrary-Lagrangian-Eulerian method with finite volume scheme is employed in the CFD model. Internal flow characteristics of the simplex atomizer as well as its performance parameters such as discharge coefficient, spray angle and film thickness are predicted. A temporal linear stability analysis is performed for cylindrical liquid sheets under 3-D disturbance. The model incorporates swirling velocity component, finite film thickness and radius which are essential features of conical liquid sheets emanating from simplex atomizers. It is observed that the relative velocity between liquid and gas phase, density ratio and surface curvature enhance the interfacial aerodynamic instability. As Weber number and density ratio increase, both the wave growth rate and the unstable wave number range increase. Combination of axial and swirling velocity components is more effective than single axial component for disintegration of liquid sheet. A breakup model for conical liquid sheet is proposed. Combining the breakup model with linear stability analysis, mean drop sizes are predicted. The theoretical results are compared with measurement data and agreement is very good.

scholarly journals Analysis of the velocity diagrams of impellers of centrifugal compressor stages after the preliminary design

2018 ◽  
Vol 245 ◽  
pp. 04004 ◽  
Author(s):  
Aleksandr Drozdov ◽  
Alexey Rekstin
Keyword(s):  
Centrifugal Compressor ◽  
Three Dimensional ◽  
Flow Path ◽  
Preliminary Design ◽  
Flow Paths ◽  
Design Program ◽  
Three Stages ◽  
Correct Application ◽  
Development Laboratory

Preliminary design is an important stape in the development of centrifugal compressors and compressor stages. Basically for this purpose, various recommendations on the choice of the flow path dimensions are applied. Researchers of the Research and Development Laboratory “Gas dynamics of turbomachines” prof. Yu.B. Galerkin and A.F. Rekstin analyzed and summarized the dimensions of flow paths of 124 impellers. On the basis of this analysis, formulas were proposed for choosing the flow path dimensions of the centrifugal compressor stages, which were included in the preliminary design program. The formulas used are designed for relative Mach number of 0.7 and isentropic coefficient of 1.4. The correct application of these formulas for other Mach numbers and isentropic coefficient required development of an appropriate approach and algorithm for adjusting the height of the impeller blades at the outlet. Calculations of gas-dynamic characteristics using the Universal Modeling Method showed the need for selecting a coefficient that takes into account the influence of viscosity to obtain the required pressure characteristics of the compressor stage. This problem was also solved in the program of preliminary design. To check the quality of preliminary design, the results were verified using a non-viscous quasi-three-dimensional calculation program. Three stages were designed for parameters different to those used for development of preliminary design formulas. Analysis of the velocity diagrams of the impeller blades and distribution of meridional velocities showed good results of the preliminary design.

scholarly journals Rapid Liquid Fuel Mixing for Lean-Burning Combustors: Low-Power Performance

2001 ◽  
Vol 123 (3) ◽  
pp. 574-579 ◽  
Author(s):  
M. Y. Leong ◽  
C. S. Smugeresky ◽  
V. G. McDonell ◽  
G. S. Samuelsen
Keyword(s):  
Low Power ◽  
Gas Turbine ◽  
Liquid Fuel ◽  
Direct Injection ◽  
Fuel Injector ◽  
Power Performance ◽  
Lean Burn ◽  
Engine Operation ◽  
Turbine Engine ◽  
Lean Direct Injection

Designers of advanced gas turbine combustors are considering lean direct injection strategies to achieve low NOx emission levels. In the present study, the performance of a multipoint radial airblast fuel injector Lean Burn injector (LBI) is explored for various conditions that target low-power gas turbine engine operation. Reacting tests were conducted in a model can combustor at 4 and 6.6 atm, and at a dome air preheat temperature of 533 K, using Jet-A as the liquid fuel. Emissions measurements were made at equivalence ratios between 0.37 and 0.65. The pressure drop across the airblast injector holes was maintained at 3 and 7–8 percent. The results indicate that the LBI performance for the conditions considered is not sufficiently predicted by existing emissions correlations. In addition, NOx performance is impacted by atomizing air flows, suggesting that droplet size is critical even at the expense of penetration to the wall opposite the injector. The results provide a baseline from which to optimize the performance of the LBI for low-power operation.

Stabilizing effect of surrounding gas flow on a plane liquid sheet

2011 ◽  
Vol 672 ◽  
pp. 5-32 ◽  
Author(s):  
OUTI TAMMISOLA ◽  
ATSUSHI SASAKI ◽  
FREDRIK LUNDELL ◽  
MASAHARU MATSUBARA ◽  
L. DANIEL SÖDERBERG
Keyword(s):  
Growth Rate ◽  
Gas Flow ◽  
Liquid Velocity ◽  
Air Flow ◽  
Liquid Sheet ◽  
Mean Velocity ◽  
Order Of Magnitude ◽  
The Stability ◽  
The Waves ◽  
Half Thickness

The stability of a plane liquid sheet is studied experimentally and theoretically, with an emphasis on the effect of the surrounding gas. Co-blowing with a gas velocity of the same order of magnitude as the liquid velocity is studied, in order to quantify its effect on the stability of the sheet. Experimental results are obtained for a water sheet in air at Reynolds number Rel = 3000 and Weber number We = 300, based on the half-thickness of the sheet at the inlet, water mean velocity at the inlet, the surface tension between water and air and water density and viscosity. The sheet is excited with different frequencies at the inlet and the growth of the waves in the streamwise direction is measured. The growth rate curves of the disturbances for all air flow velocities under study are found to be within 20% of the values obtained from a local spatial stability analysis, where water and air viscosities are taken into account, while previous results from literature assuming inviscid air overpredict the most unstable wavelength with a factor 3 and the growth rate with a factor 2. The effect of the air flow on the stability of the sheet is scrutinized numerically and it is concluded that the predicted disturbance growth scales with (i) the absolute velocity difference between water and air (inviscid effect) and (ii) the square root of the shear from air on the water surface (viscous effect).

Test Response of a Turbocharger Supported on Floating Ring Bearings: Part I — Assessment of Subsynchronous Motions

2003 ◽  
Author(s):  
Chris Holt ◽  
Luis San Andre´s ◽  
Sunil Sahay ◽  
Peter Tang ◽  
Gerry La Rue ◽  
...  
Keyword(s):  
Ambient Temperature ◽  
Test Data ◽  
Natural Frequencies ◽  
Comprehensive Analysis ◽  
Experimental Results ◽  
Inlet Pressure ◽  
Rotor Speed ◽  
Test Response ◽  
Feed Pressure ◽  
Feed Temperature

Measurements of casing acceleration on an automotive turbocharger running to a top speed of 115 krpm and driven by ambient temperature pressurized air are reported. Waterfall acceleration spectra versus rotor speed show the effects of increasing lubricant inlet pressure and temperature on the turbocharger rotordynamic response. A comprehensive analysis of the test data forwards regimes of speed operation with two subsynchronous whirl motions (rotordynamic instabilities). Increasing the lubricant feed pressure delays the onset speed of instability for the most severe subsynchronous motion. However, increasing the lubricant feed pressure also produces larger synchronous displacements. The effect of lubricant feed temperature is minimal on the onset and end speeds of rotordynamic instability. Nevertheless, operation with a cold lubricant exhibits lower amplitudes of motion, synchronous and subsynchronous. The experimental results show the subsynchronous frequencies of motion do not lock (whip) at system natural frequencies but continuously track the rotor speed. No instabilities (subsynchronous whirl) remain for operating speeds above 90 krpm. Bearings greatly influence turbocharger (TC) rotordynamic performance.

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