الفهرس 
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Abstract
An experimental study of two swirling jets of fuel and air in a cylindrical oil fired model combustor is carried out in the present work. The combustor is cooled by air and equipped at its inlet by different air swirlers. A pressure swirl atomizer is mounted inside the air swirler. The inner diameter and the total length of the swirl combustor are 250 and 915 mm, respectively. Six air swirlers are chosen to cover a wide range of swirl numbers of 0, 0.23, 0.5, 0.78, 1.5 and 3.5. Three spin chambers with different angles of 30, 60 and 90 degrees are used to impart the swirling motion for the liquid fuel. The fuel used is commercial Kerosene. Different nozzle diameters of 0.3, 0.4, 0.5, 0.6 and 0.7 mm are used.
The main parameters considered in the present work are air flow rate, fuel flow rate, burner load ( thermal load ) i.e. air to fuel mass ratio, air swirl strength and atomizer geometry ( nozzle diameter and spin chamber angle ).
The characteristics of the pressure swirl atomizer used at cold condition are also studied by determining the flow number and the discharge coefficient when using different atomizer geometries.
The spray combustion characteristics are studied by changing either the spray quality, or the combustion air condition. Theeffect of spray quality can be carried out by changing the atomizer geometry or the fuel injection pressure ( fuel flow rate ) . The combustion air condition is changed by using air swirlers having different swirl numbers or using different air flow rates.
Measurements of lean blow-off limits , flame stability, visible flame length, temperature patterns and species concentrations ( C02 and 02 concentrations ) under different operating conditions are carried out. The temperature is measured by a water-cooled bare wire thermocouple while the species concentrations are measured by using a chemical gas analyzer ( BAKHARAKH model ). The concentrations of O2 are checked by using digital 02 meter ( Model OM-5 ).
The experimental results show that the flame stability is improved by increasing the swirl number or spin chamber angle and by decreasing nozzle diameter. from the temperature and species concentrations contours, two main reaction zones are formed. For strong swirl flame of S > 0.5, the first reaction zone is formed upstream, relatively, far from the flame center line while the second one is formed downstream around the flame axis. For weak swirl flame there is only one reaction zone located around the flame axis.
The flame length decreases by increasing air to fuel mass ratio, swirl number and nozzle diameter. The same trend isobserved also for spin chamber angle, when using a small nozzle diameter for all operating conditions except for low air flow rate with weak swirl of 0.23. Using dn == 0.5, the flame length increases, generally, by increasing spin chamber
angle.
Finally, five empirical formulae are obtained which covering the whole studied operating region. The first one is made for getting the fuel mass flow rate at the blow-off limits which related with the effective and considered parameters in the present work. The others formulae are described the relation between the flame length and all different parameters.