الفهرس 
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Abstract
The present thesis represents experimental investigation which is directed towards the better understanding of performance and characteristics of water piston engine which is considered to be one of the internal combustion engines family. It works in a liquid media such as water and uses a part of it as a piston which attains an impulse force from the exhaust gases of the combustion of fuel, subsequently the piston applies a thrust force on the engine itself.
The construction of this engine is cheap and simple with almost no maintenance, no external or internal rotary parts, moreover it is easy to operate and can be used in rural areas where maintenance is not available.
The main parameters under investigation in the present thesis are:
a) Developing a complete understanding of the working cycle of the engine.
b) Study performance of the engine under different operating parameters circumstances.
c) Construct operational charts to use in practice for optimum performance.
d) Construct a mathematical model for combustion of the mixture inside the engine.
The experiments have been carried out on a water piston engine which has been designed and constructed in the heat engine laboratory of Mechanical Power Department, Shobra Faculty of Engineering, Zagazig University. The engine has been designed with a complete facility to offer a considerable matrix of experimental options, which could be adjusted, namely, air valve clearance, spark plug and ejector location, vertical and total immersed lengths.
A commercial gaseous fuel was used to operate the engine which has a volumetric composition of 70% butane and 30% propane, supplied to the engine by an ejector specially designed for the engine under consideration.
The test rig has been supplied with an effective measuring equipment such as a locally designed computerized A/D system. Adjusted to plot an accurate pressure- time diagrams and a hydraulic power cylinder with a pressure gauge to measure engine thrust. Moreover an ignition system was designed to overcome the spark failure due to engine wet conditions.
The experiments gave a set of pressure-time diagrams at different operating circumstances. These diagrams were recorded and analysed by special designed computer programs. The obtained results were represented in terms of group of curves from which this engine characteristics have been demonstrated.
The cyclic variation of this water piston engine was relatively high, and it was found that the engine should run at its optimum operational conditions, otherwise cyclic variations caused a quick engine failure.
A mathematical model for combustion of the maximum inside the engine combustion chamber in the form of:
Xb=1-exp{-a (tb)(m+1}
Has been investigated for the water piston engine.
A computerised fine group of direct photographs were recorded at specific operational conditions using a movie camera (Panasonic 3500), and a computer video card.Moreover, can actual operating trial of engine has been achieved on The River Nile, where a small boat, of about 150 kg in weight, carrying five persons was sailed by the thrust force produced from the designed water piston engine, for one hour at an average speed of 4 km/hr.