Mindblown: a blog about philosophy.
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INTRODUCTION
The process of producing cold by artificial means may be called refrigeration. The term ‘refrigeration’ may be defined as the artificial withdrawal of heat, producing in a substance or within a space, a temperature lower than that which would exist under the natural influence of surroundings. In other words, the refrigeration means a continued extraction…
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THRUST WORK, PROPULSIVE WORK, AND PROPULSIVE EFFICIENCY FOR ROCKET ENGINE
Neglecting the friction and other losses, we have Rocket propulsive efficiency Example 17.1 A turbo-jet unit consists of single stage compressor, single stage turbine, and nozzle. The pressure and temperature at the inlet of compressor are 0.8 bar and 280 K, respectively. The pressure at the outlet of compressor is 4.5 bar. The following data…
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BASIC CYCLE FOR TURBO-JET ENGINE
The basic cycle of a turbo-jet engine in T-s diagram is shown in Fig. 17.7. The various processes are as follows: Process 1−2: Isentropic diffusion of atmospheric air from velocity c1 to c2 = 0 with diffuser efficiency of 100%. 1−2′ is the actual diffusion with diffuser efficiency ηd from p1 to p2. Process 2′−3: Isentropic compression of air in the compressor from p2 to p4. Process 2′–3′ is…
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JET PROPULSION V’S ROCKET PROPULSION
Table 17.1 shows the comparison of jet propulsion and rocket propulsion. Table 17.1 Comparison of jet and rocket propulsion
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Rocket Propulsion
In a rocket engine, the fuel and the oxidiser are stored in the propelling body. The rocket can function in a vacuum and is the only device capable of space flight. Rockets may be of the single-stage or multi-stage type, consisting of one or more rocket motors. They may be solid propellant or liquid propellant…
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JET PROPULSION SYSTEMS
Jet propulsion systems may be classified as follows: 1 Screw Propeller The line diagram of a screw propeller is shown in Fig. 17.1(a). The schematic arrangement and the corresponding T-s diagram are shown in Fig. 17.1(b) and Fig. 17.1(c), respectively. In this system, full expansion takes place in the turbine, and the total power developed by the turbine is…
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PRINCIPLE OF JET PROPULSION
Jet propulsion is the thrust produced by passing a jet of fluid in the direction opposite to the motion of the object. The propulsive thrust in jet propulsion is obtained by the reaction of the engine produced by the exit of high velocity fluid stream from the nozzle. In case of a jet engine, the…
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Example 16.18
A gas turbine unit receives air at 100 kPa and 300 K and compresses it adiabatically to 620 kPa. The fuel has heating value of 44180 kJ/kg and fuel/air ratio is 0.017 kg fuel per kg air. The isentropic efficiencies of the compressor and the turbine are 88% and 90%, respectively. Calculate the compressor work,…
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COOLING OF BLADES
The thermodynamic analysis of the gas cycle shows that the efficiency of the cycle depends on the range of maximum temperature of the gas. If maximum temperature is increased, efficiency of the cycle is also increased. Any increase in the maximum temperature of gas results in an increase in the blade temperature, thereby inducing more…
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BLADE MATERIALS
Materials used in the manufacture of the blades consist of mainly three different elements, namely iron, nickel, and cobalt with chromium which forms one of the major alloying elements, since it gives high resistance to oxidation. Other alloying elements that have been used include most of the metals of the periodic table. Materials working under…
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