Flow in diffusers in aircraft as well as flow in nozzles in both aircraft and rockets are discussed. An analysis of ideal and real cycles as well as performance parameters for all engines is identified.
Introduction
However, by ignoring the contribution of the tails of birds in flight control, he fell and was injured (but did not die) when he tried to return to the ground. Author of the present book introduces propulsion systems in a rather new flavor to both aeronautical and aerospace industries.
Classifications of Aircrafts .1 General.1General
Aerostats
Aerodynes
Fixed-wing types and rotorcraft can be further divided into powered and non-powered (gliders) as detailed below. The fourth group can be divided into three groups, namely: lifting body, flapping wing (ornithopter) and fan wing.
Fixed Wing Aircrafts
Some of these aircraft are powered by turbofan engines, while others are powered by turboprop engines as seen in Fig.1.30. All are powered by turbofan engines, except T-38, which is powered by afterburning turbojet engine.
Rotorcrafts (Rotor-Wing Aircrafts)
All helicopters are powered by turbo shaft engines, except small types which are powered by piston engines. All are powered by turboshaft engines except the Sikorsky H-19, which is powered by radial engines.
Hybrid Fixed/Rotary Wings
Northrop Grumman Corporation's RQ-8 Fire Scout unmanned aerial vehicle (UAV) can successfully launch two missiles and has the capability of vertical landing on a moving ship without a pilot controlling the aircraft. A coleopter is a type of vertical take-off and landing aircraft design where the fuselage is surrounded by ring wings. SNECMA's experiences demonstrated outstanding control problems, both with balancing the aircraft during vertical flight and transitioning between vertical and horizontal flight and back.
It differs from previous tiltrotors in that, instead of each rotor, it consists of long blades attached to a central rotary ring; it has a single rotary ring, the diameter of which is equal to the entire wingspan of the aircraft, with the ring attached to the wingtips [19].
Other Methods of Lift Aircrafts
Its makers claim that it is the first integral lift and power wing with horizontal rotors in history to sustain flight. It is an aerodynamic, military and combat aircraft with fixed wings. In addition, it is usually powered by a turbofan engine with afterburner. Bomber is also an aerodynamic, military and fixed-wing combat aircraft. It is powered by a turbofan or turboprop engine.
Tiltwingan aerodyne, fixed/rotary wing hybrid vehicle, research military non-combat aircraft. It is powered by a jet engine.
Classifications of Propulsion Systems
External Combustion
The ANP also contained plans for two B-36s to be modified by Convair under project MX-1589; one of the B-36s would be used to study defense requirements for an airborne reactor, while the other would be the X-6. Based on the results of the NTA, the X-6 and the entire nuclear aircraft program were abandoned in 1961. The main purpose of the flight phase was to examine the effectiveness of radiation protection, which was one of the main concerns of the engineers.
Budget constraints and the development of new conventional aircraft designs were cited as the main reason for the cancellation of the program in August 1966.
Internal Combustion
Examples of turbojet engines are the General Electric GE J33 (jet fighter powered - Lockheed P-80) and the GE J35 (powered first Boeing XB-47, Northrop YB-49A flying wing and Douglas D-558-1). The ratio of air passing around the engine to air passing through the core is called the bypass ratio. One of the problems with the rear fan setup is hot gas leaking from the LP turbine to the fan.
At high speeds (above Mach 2.4), the engine used variable geometry vanes to direct excess air through six bypass lines from downstream of the fourth compressor stage to the afterburner.
Other Power Sources
As of December 2008, it was the only manned solar-powered aircraft in flight and is regularly operated by Solar Flight (Fig.1.80). Turbofan engines are the most widely used air-breathing engines in both civil and military fixed-wing applications. Detailed analyzes for all the above power plants will be given in this book.
Give details of the engine; number of axles, power, propeller type, possible installations to other aircraft.
Introduction
System and Control Volume
Fundamental Equations
Conservation of Mass (Continuity Equation)
That is, the net rate of mass flow across the control surface is equal to the rate of mass decrease within the control volume. If the flow is steady relative to a fixed reference in the control volume, all properties of the fluid, including the density at any fixed position in the reference, must remain constant with time. The right side of Eq. 2.4) then vanishes, and on the left-hand side of this equation, we can extract ρ from under the integral sign.
We assume that the flow is steady relative to the control volume and that the inlet and outlet flows are one-dimensional.
Linear Momentum (Newton’s Second Law)
It also defines a control volume that the control surface passes through the engine outlet plane (2) and extends far upstream at (1). Fis is the vector sum of all forces acting on the material within the control volume, which are surface forces (compressive force as well as reaction to compressive force through the structural support denoted by τ) and body force (which is gravity here). If the sides of the control volume are assumed to be sufficiently far from the engine, then the lateral mass flow rate exits the control volume almost in the x-direction.
Example 2.3 The idling turbojet engines of a landing aircraft produce forward thrust when operating normally, but can produce rear thrust if the jet is properly deflected.
Angular Momentum Equation (Moment of Momentum)of Momentum)
Since the mass of the system is fixed so that the limits of the integration on the right-hand side of Eq. The integral on the left side of the equation represents the total moment about point (a) of the external forces acting on the system and can be given as The terms on the right-hand side represent the outflow of momentum through the control surface plus the rate of increase of momentum inside the control volume, both quantities being observed from the control volume.
What is the transverse torque on the turbine if the air mass flow rate is 100 kg/s.
Energy Equation (First Law of Thermodynamics)
So for the time we have variations of stored energy and energy in transition for a system. To develop the control volume approach, we will consider to be the extensive property to be used in the Reynolds transport equation. Equation (2.19) then states that the net rate of energy transferred to the control volume by heat and work is equal to the rate of outflow of stored energy from the control volume plus the rate of increase of stored energy within the control volume.
Referring to Fig.2.9, the time rate of the work leaving the control volume—the total rate of flow work—is given as
The Second Law of Thermodynamics and the Entropy EquationEquation
Irreversible processes are processes that involve one of these characteristics: friction, heat transfer with finite temperature gradient, mass transfer with finite concentration gradient, or unbounded expansion. For a small system consisting of pure matter in the absence of gravitational motion, then if the properties are uniform throughout the system, then the first law is for incremental changes. If the system experiences a reversible process for which the incremental workdw¼pdv, then from Eq.
Equation of State
If Cvis constant, the gas is called calorically perfect, and the internal energy is given by. Similar to internal energy, the enthalpy of thermally perfect gases depends only on temperature, or. Example 2.6 The constant specific heat of the volume of an ideal gas varies according to the equation Cv¼aT2, where¼2:32.10% 5kJ=kg:K3.
If the gas is heated at constant volume from 50 to 80!C, find the change in entropy.
Steady One-Dimensional Compressible Flow
Isentropic Relations
For a given fluid (γ,R) and inlet condition (P0,T0), it can be easily shown that the mass flow rate per unit area is maximum at M¼1. By indicating the characteristics of the flow at M¼1 with an asterisk, the maximum flow per area unit. For a given isentropic flow and known (γ,R,P0,T0,m_:), it is clear that A* is a constant, so we can use these relations to plot the fluid properties against Mach number (Fig.2.11) .
Sonic Conditions
With these ratios, the ratios of the temperature, pressure, density and speed of sound, referred to their stagnation values, can be expressed by the critical Mach number:.
Classification of Mach Regimes
Diffusers and Nozzles
Equation (2.59) tells us how the velocity (V) changes when the area (A) changes and the results depend on the Mach number (M) of the current. On the contrary, a decrease in surface area causes an increase in velocity, which is the case with a nozzle. An increase in surface area (dA>0 ) then results in an increase in velocity (dV>0) or a nozzle.
In the case of the CD nozzle, if the flow in the throat is subsonic, the flow downstream of the throat will slow down and remain subsonic.
Shocks
Stokes' equations can be used to describe the flow between the upstream and downstream ends of the compression stroke. But the divergent part of the nozzle still acts as a diffuser, slowing the fluid down to subsonic speeds. Thus, decreasing Pbfurther has no effect on fluid flow in the converging part of the nozzle or on the mass flow rate through the nozzle.
The fluid then continues to decelerate further into the remaining portion of the convergent-divergent nozzle.
Rayleigh Flow Equations
The Standard Atmosphere
This calculation shows that at the outer edge of the troposphere, where the temperature is 56.5 °C, the absolute pressure is about 23 kPa. If the exit velocity of the combustion products is 800 m/s relative to the airplane, what is the total reverse thrust of the airplane if it is moving at a speed of 180 km/h. If the plane changes to an angle of inclination of 20o, what will be the speed of the plane when it reaches uniform speed.
For the same acceleration value as calculated above and if the drag force is proportional to the speed squared of the plane, what will be the aircraft speed.
Introduction
Fuel consumption is properly evaluated by a parameter defined as thrust-specific fuel consumption, which is the ratio between the rate of fuel flow into the engine and the thrust generated. Aircraft range is a combined engine/aircraft parameter where fuel consumption through the engine is related to the lift and drag forces of the aircraft.
Thrust Force
For turboprop engines (Fig.3.2), the high value of thrust is obtained by the very large amount of airflow rate, although the exhaust and flight speeds are very close. The air mass flow rate is constant and equal to 40 kg/s regardless of the variation of flight speed. The mass flow rate is constant and equal to 40 kg/s at height 9 km The momentum thrust (Tmomentum) is constant and given by the relation.
Variable mass flow rate at altitudes of 3, 6 and 12 km and constant discharge pressure of Pe¼87.50 kPa.
Factors Affecting Thrust
- Jet Nozzle
- Air Speed
- Mass Air Flow
- Altitude
- Ram Effect
It depends on temperature and air pressure as both together determine the density of the air entering the engine. Additionally, increasing airflow will increase thrust, which is sketched by 'B'. Rotational speed (rpm), which affects both compressor pressure ratio and turbine performance.
The first group thus contributes to both the air mass flow rate and the jet velocity.
Engine Performance Parameters
Propulsive Efficiency
