Selection Parameters for Engines for the Aircrafts - Lab Report Example

Title: FJ-33-4 engine Dated: March 31, 2010 Engine Selection: Engines for the aircrafts are selected on the basis of certain key parameters for the achievement of the desired results through their performance and delivery of the services. Engine Selection Parameters There are four key parameters which are considered for the selection of the outstanding engine to fulfill the aircraft needs. These key parameters are listed as under: 1. Thrust: The Thrust parameter is selected with the observance of sea- level thrust. The current fan engines create about 60 kN of the sea-level as static thrust per square meter of fan face area as faced by the engine of the aircraft. Therefore, the thrust level tends to determine the size of the engine of the aircraft. The FJ-33-4 engine for the aircraft has been selected to make sure that the recommended specifications of the engine matches the requirements within the range of +5%, - 0% of the contained allowance. The possible selection of the engine in the cruise will help in managing the best specific fuel consumption (sfc), to overcome the stress on the aircraft as the under-sized engine like FJ-33-4 has the ability to meet the technical requirements while its performing and the service life of the engine will also be improved. 2. Specific Fuel Consumption, c /hour: For low operating cost design, low specific fuel consumption as a key parameter is considered for the selection of the aircraft engine for achieving the target of low sfc and to safe the fuel in the aircrafts. The proposed objective will help in the achievement of profits instituting payload and the same could be used to produce the Operational weight of the design low and if the operational weight of the aircraft is low, the same will lead to make the manufacturing cost to the lower side along with the inferior direct operational costs. 3. Weight: The third key parameter for the selection of the engine of the aircraft is the weight of the aircraft. The target in the shape of long range designs engine lead to establish the target of cruise speed to lower than that of the maximum range speed. This speed will lower the cruise drag and similarly, the weight of the engine will also be reduced. These specifications that are in the shape of low thrust, economical consumption of fuel will lead to the selection of smaller and lighter engine with the desired performance for the aircraft and the FJ-33-4 is the best selection as engine of the aircraft. 4. Size: The size of the aircraft’s engines has a relationship with the value of the thrust as produced by the aircrafts while during their operations. An increase in the engine’s fans diameter has a positive relationship that is to produce large amount of thrust as a product. Similarly, there will be a problem in the installation of the engines in the aircrafts under their wings along with the problems of greater drag, an aerodynamics force that opposes aircraft’s motion in the air. The engine selection is accomplished while considering elimination of the two potential problems as a) ground clearance might not be compromised at any cost and sufficient space must be available between the engine of the aircraft and the ground for safety reasons during the physical operations of taking off and landing, and b) the cowl drag predictions during high power/ low speed operations should be concluded to demonstrate satisfactory statistics for feasible flight operations. Engine Design Parameters: The engine performance is regulated by a number of guaranteed design parameters which cold effects the engine performance during flight operations and the same leads to influence engines selections parameters as have already been discussed. These parameters have been taken into consideration while considering the engine selection for the aircrafts. These parameters are as under: a) Turbine Entry Temperature ( TET ): The Turbine Entry Temperature (TET) is the level where temperature of the engine goes to its maximum state. As the material property of the turbine’s blades varies, therefore, it is an essential requirement to maintain a temperature within certain limits. An increase in the thrust per unit air mass flow rate of the engine with minor effect of increasing the sfc will lead to increase in the TET. Any increase in the TET demands an additional cooling to bring the engine temperature down with minor increase in the weight of the engine. The latest aircraft’s engines are supplemented with the best blades cooling techniques with the use of the best materials resulted in TET increase around 1700k, and the same could be adjusted with the use of cooling techniques in the engines. b) Pressure Ratios ( PRbp and PRgg ): For fan engines, there is a relationship between by-pass ratio jet velocity and hot jet velocity and the pressure of the by-pass is linked with pressure of the gas generator. An increase in the pressure of the gas generator tends to have a beneficial result on lowering the sfc, however, any increase in the value of the pressure ratio which is larger than 10 will reduce the specific thrust. The modern aircraft engines have pressure ratio in the range of 35 to 45 and if the engine needs some higher pressure, the same is adjusted through negligible weight increase in the engines. c) Bypass Ratio ( BPR ): The ratio between the mass flow rate of air drawn in by the fan of the engine but by-passing the engine core to the rate of mass flow which passes through the engine core is called as By-pass Ratio (BPR). Lower exhaust speed is the outcome of the high bypass ratio which in turn reduces the specific fuel consumption. On the other hand, higher exhaust speed is the result of the lower bypass ratio as a requirement of the supersonic aircrafts with an increase in the specific fuel consumption. An optimum bypass ratio for is selected the jet engines for their optimum performance in terms of fuel consumption and for a particular distance that will be covered through the aircraft operations. An increase in the BPR ratio beyond 10 has very little advantage in the reductions of sfc. Wing mounted Engines: Wing mounted engines help in the installation of engines in the wing root which has minimum parasite drag along with minimum weight which further minimizes yawing moment as a result of the asymmetric thrust in case of engine failure. On the other hand, these structures pose a series threat to the basic wing structure in the event of a turbine disk or blade failure. If a smaller diameter engine is required in latest version of the airplane, the same could be achieved through necessary modifications in the wing structures of the aircraft. These installations also reduce the flap in the engine exhaust region, thus a reduction in the CLmax. Engine thrust: The amount of thrust as required for the engine to fly is calculated with the help of thrust to weight ratio (). The ratio is a dimensionless quantity which also indicates performance of the aircraft and the engines. A = 0.3 has been used for the determination of the ratio where T = thrust and W is the maximum takeoff weight = 2827.551 KN. The equation helps in the calculation of T, for example in the said equation T= 0.3 x 2827.551 =848.3Kilonewtons = 190 705.426 pounds force The FJ-33-4 engine: The FJ-33-4 engine for the aircrafts has been selected through a comparison of the available brands of the engines of the kind. The following four brands have been considered as: 1. FJ-33-1 Static thrust (lbf) 1,200 Specific fuel consumption (lb/(h·lbf)) SLS, ISA 0.486 Bypass ratio 3.28 Dry weight (lb) Read More