Ejection velocity

Example 1. A gas is confined in the bore of a cannon of length L by a shell of mass M and cross-sectional area A. Initially, the shell is at a distance Lt from the end of the cannon. Assuming 1 atm pressure, find an expression for the ejection velocity of the shell in terms of the work done by the expanding gas. 

A simple model of an electrostatic accelerator allows equating the kinetic energy of the ejected propellant with the electrical energy emended, to produce the ejection velocity ... 

Since the air pressure decreases with increasing flight altitude, at constant nozzle diameter, the total thrust increases with increasing flight altitude. This increase can correspond to approximately 10 to 30 % of the total thrust depending on the rocket. The maximum thrust is reached in vacuo. The so-called effective ejection velocity ceff (of the combustion gases) is defined as the ratio between the thrust and the mass flux (dm / dt) ... 

The effective ejection velocity is an average. In reality the velocity distribution is not constant throughout the whole nozzle diameter. Assuming a constant ejection velocity allows a one-dimensional description of the problem. 

The effective ejection velocity ceff is different from the specific impulse 7sp only due to g0 (see above). 

The so-called rocket equation describes the fundamental equations of rocket propulsion. If we consider the simplest case, in which a monostage rocket accelerates in a gravity-free vacuum, i.e. a slow-down due to gravitation and friction is not taken into consideration. When the rocket has a velocity of zero at the start and ejects the propellant with a constant ejection velocity ue, the velocity u of the rocket after time t corresponds to ... 

The time available for the drops to dry depends on their average velocity and the radius of the dryer (Figure 14-13). In the small machine you want a small radius you get this by minimizing the velocity of the drops. This requires low ejection velocities and low air circulation velocities. (The two are related). In the large machine drops have to move away quickly from the atomizer to minimize collisions and agglomeration. This is a very different requirement. 

It is necessary to know the velocity distribution of ejected fragments in order to estimate tlie re-accumulation condition for icy bodies. However, this velocity distribution is not known for ice. For this reason, we used the antipodal particle velocity (va), for each collision as the lowest fragment ejection velocity. We also used the criterion, for the re-accumulation condition. In tliis... 

Fig. 7-13. Vertical flux of sea-spray droplets according to Monahan (1968), compared with the number density size distribution of sea-salt particles 6 m above the ocean surface (Chaen, 1973, as reported by Blanchard and Woodcock, 1980). Both follow a Junge (r ) power law. Numbers next to points indicate the wind speed (m/s). The solid line for the droplet flux was calculated from ejection velocities given by Wu (1979).

We established the scale-up rules to design DFC burners, mainly using numerical simulation. We optimized the scale-up rules for the ejecting velocities and their nozzles arrangement of the raw material and each gas. We also optimized the rules for the distance between the burner and the surface of the molten glass. On the bases of these optimized rules for scale-up, we designed and manufactured a pilot-scale DFC burner. 

The mass flow rate of the engine being rhS, and with m being the unit mass flow rate of propellant and S the cross-sectional surface area of the engine outlet, the thrust of the rocket is given by the momentum balance T = mS g, with the ejection velocity of the propellant in relation to the body of the rocket. The specific impulse is equal to the thrust provided per unit weight of propellant consumed (and therefore ejected) ... 

Our observations support jet-driven lobe models for CO outflows (Masson and Chemin 1993) and suggest that prompt and steady state entrainment might be occurring (DeYoimg 1986). However, ejection of discrete bullets with a time variable ejection velocity cannot be ruled out by our data. 

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