Nozzle Less Propulsion

Abstract:

In Rockets and Missiles combustion gas of an integral burning of a propellant flows along the duct of the propellant. If the nozzles attached to a rocket motor are removed, the pressure on the duct becomes equal to atmospheric pressure and no sonic velocity is attained at the rear end of the duct. Then no thrust generated by the combustion of the propellant. In nozzleless propulsion the mass burning rate of the propellant in the duct is increased and the flow reaches sonic velocity the increased pressure in the duct is converted in to thrust.

Current paper deals with such an area of nozzles propulsion experimental results and current utilization in the aerospace propulsion. Nozzleless Propulsion is a propulsion unit for the acceleration of a self propellant vehicle such as missiles or a rocket is loaded with a propellant block secured laterally to the body of the propulsion unit by means of a combustion inhibitor and has more than aspect ratio of 6.0. The propellant blocks has one axial duct and at least 6 peripheral ducts and one upstream face, is required with a fitting secured to the body of propulsion unit. This fitting provides a free space between the upstream face of the propulsion unit the axial duct and the peripheral ducts opening into this free space via orifices made in the fitting. The combustion gases are ejected rearward without being fed through a nozzle. Sonic velocity is achieved downstream of the ducts.

Experimental results are presented for four nozzleless motors of different length-diameter (L/D) ratios using two different composite propellants. The experimental observations discussed are: the premature unchoking in motors of insufficient L/D ratios and the tendency for the propellant to extinguish under highly negative pressure gradient environment, both peculiar to nozzleless operation.

A simple one dimensional numerical scheme is presented to predict the performance of a nozzleless solid motor. Erosive burning, elastic grain deformation and L/D ratio-dependent combustion efficiency are considered in the scheme. A relatively simple procedure is followed to account for the coupling effect between port gas dynamics and elastic grain deformation. The experimental results are compared with those predicted by the numerical scheme. The predictions are in reasonable agreement with the experimental values. For a composite propellant the burning rate index n can significantly vary with respect to pressure. The application of this fact plays a very important role in accurately predicting the thrust-time trace of nozzleless motors.

-----------------------
NOZZLELESS PROPULSION SYSTEM

(RECENT TRENDS IN AEROSPACE PROPULSION)

By- Mr.Thamim Ansari.(B.E Aero) ,S. AmmaDurai(B.E Aero).
Park college of Engineering and Technology, Coimbatore.
Ph no : 9944119506
Mail ID: [e-mail]
[e-mail]