By CGTrader on March 20, 2020 13:50
3dmax9 version production Rendering by V-ray 2.0 Welcome to my personal space for browse more models. The F119 engine consists of a three-stage fan, a six-stage high-pressure compressor, an annular combustor with pneumatic nozzle, a floating-wall flame cylinder, a single-stage low-pressure turbine, an afterburner and a two-dimensional vector nozzle, etc. The whole engine is divided into six units: fan, core engine, low-pressure turbine, afterburner, nozzle and accessory transmission casing. In addition, there are accessories, FADEC and engine monitoring system. YF120 engine, which competes with F119, is a variable cycle engine. It has an adjustable connotation air outlet ring behind the second stage fan. In high-pressure compressor, the first stage working blade is made longer and becomes a fan, which is called the fan driven by the core engine. Then there is an air outlet ring flowing to the outer connotation, which is always open in the work, so it is called the main fan. Outside the air ring. At low operating conditions, the two outer culverts are opened to increase the culvert ratio to achieve low fuel consumption; at large operating conditions, the adjustable exhaust ring behind the two-stage fan is closed, and the engine becomes a turbofan engine with small culvert ratio , in order to increase the unit thrust. The pressure matching between the fan and the core engine is achieved by diverting the air flow from the outer culvert to the afterburner through a variable area culvert ejector (VABI) installed in front of the afterburner. In addition to cooling the heat shield of the afterburner, VABI also injects excess air into the exhaust gas in front of the throat of the tail nozzle to increase thrust. YF120 has one stage fewer fans and compressors than F119, and there is no guide blade between high and low pressure turbines, so YF120 has five rows fewer blades than F119. Table 4 lists the main structural differences between GE's YF120 and Pratt & Whitney's YF119. In the overall structure design of F119, there are two prominent changes compared with Pratt & Whitney's previous engines. One is that the high-pressure rotor support mode is changed to GE's usual form, and the other is that the high-pressure turbine adopts a single stage. In the civil engine (JT9D, PW2037 and PW4000) and military engine (F100) developed by Pratt & Whitney Corporation in the late 1960s, the high-pressure rotor is supported by 1-1-0, that is, the ball bearing in front of the high-pressure compressor and the back fulcrum in front of the high-pressure turbine, that is, the high-pressure turbine is cantilever supported, and the load of the bearing is 1-1-0. Outgoing through the combustion chamber casing. The support sketch of the F100-PW-100 engine shown in Fig. 5 is its representative. This design not only makes the number of bearing frames of the engine more, but also makes the diameter of the shaft smaller and the turbine disk cantilever supported, which makes the dynamic design of the rotor difficult. In GE's engines (F101, F110, F404 for military use and CFM56 for civil use), the high-pressure rotor is supported by 1-0-1, that is, the rear fulcrum of the rotor is located behind the high-pressure turbine, and the intermediate bearing is adopted, that is, the outer ring of the bearing is fixed on the high-pressure rotor, and the inner ring is fixed on the low-pressure rotor. This arrangement not only reduces the load-bearing frame, but also makes the diameter of the high-pressure turbine shaft very large and increases the rigidity of the rotor. Its disadvantage is that the lubrication and sealing of intermediate bearings are more complex. In the development of F119, Pratt & Whitney changed its previous way of supporting high-pressure rotors by adopting the design of intermediate bearing with 1-0-1 and rear fulcrum in F110 and F404. Fig. 6 shows a sketch of the F119 engine, from which we can see how the high and low pressure rotors are supported and the main design features of each part. Pratt-Whitney also uses 1-0-1 high-pressure rotor support in its latest civil engine PW8000. This design change deserves attention. In the design of high-pressure turbines, Pratt-Whitney began to develop engines in the late 1960s, such as its large, civil engine JT9D, PW2037 and PW4000, as well as military engine F100, using two-stage design. This design makes the load of each stage turbine smaller and the efficiency of the turbine larger, but it brings the disadvantages of more parts and heavy weight. GE has adopted single-stage high-pressure turbines in the engines developed in the same period (military: F101, FllO and F404, civil: CFM56). Although the efficiency of the turbines is slightly lower, it has received the advantages of simple structure, less teaching of parts and light weight. In the design of F119, Pratt & Whitney also changed its previous practice and adopted the design of single stage high pressure turbine (see figure 6). This change is also to improve the thrust-weight ratio.