الأبعاد النفسية والتربوية في نظر سيدنا عمر بن الخطاب تجاه القدس

When looking at the history of every human civilization, one may find some people or places that go down in history, and their biography does not disappear until God inherits the land and those on it. One of these places is the city of Jerusalem, a city where no two differ on its importance. A city that is home for sanctuaries, history, and monuments and every inch speaks of its greatness. Especially in the history of Islam, which linked it wonderfully to the Qibla of Muslims (the Sacred Mosque) after it was the first Qibla in the history of Islam. This high standing link was perpetuated by the Holy Qur’an in Surat Al-Isra and in many other places. This research has shown its importance to Muslims, the reason Muslims love it and their dedication to defending every single grain of its sand, and how did the esteemed Companions view it? This research spoke about some of the aspects that are related to the personality of our master Omar bin Al-Khattab, may God be pleased with him, (which are the psychological and educational aspects) while looking at the importance of Jerusalem to him, may God be pleased with him, which existed since pre-Islamic time and how it extended to the time of Islam and has emerged during his caliphate, may God be pleased with him.

Improved Technique for the Calculation of Heat Transfer in a Thrust Chamber

Advancements in rocket propulsion have been the key factor for the scientific progress especially in space exploration and communication. The continued quest to achieve higher propulsion velocities at low cost still provides the room to the scientists and engineers to work on the development in the design of thrust chamber of a rocket engine. Given the high manufacturing and operational cost of rocket engines, precise knowledge of the chamber dynamics, propellants flow and feed system, heat transfer and structural integrity are important. During operations the thrust chamber experiences high temperatures and pressures, thus a reliable design requires adequate knowledge of the flow and combustion physics inside the chamber. A number of ways have been employed by the researchers to optimize heat transfer and performance of the engine. Generally regenerative cooling along with film cooling are used for safe operation.For small LPREs with small mass flow rates of the coolant, safety of the chamber wall becomes challenging job. Structural integrity can be attained by specific heat transfer rate and efficient combustion will give better performance. Numerical estimation of heat transfer using commercial software may be help for design and mounting instrumentation for experimentation at proper place. However one requires an integrated design tool for designing a thrust chamber with optimal performance ensuring adequate thrust, structural integrity and efficient cooling. For optimization of such a thrust chamber, couple fluid-structure-heat transfer analysis is often complicated and requires huge computational resources using commercial software. The combustion chemistry is often approximated through one dimensional theory. Generally experimental/empirical correlations are used for heat transfer rate calculations or one has to rely on expensive testing to validate structural design and safe operation. However the high cost involved with experimentation and manufacturing of even a small chamber, an integrated tool for optimal design of thrust chamber can be helpful. The optimized geometry can be numerically simulated for confirmation before leading to actual use. The integrated design tool can help in obtaining optimal thrust under given dimensional and flow constrains with adequate heat transfer rates ensuring low design cost. The major aim of this research work was to develop an in-house integrated software tool for the design and optimization of the coolant channel configuration of thrust chamber of a rocket engine. However, the study also includes the experimentation and CFD study for the validation of the tool developed. The developed integrated tool includes seven modules providing optimal performance parameters for a given thrust chamber design. The modules include combustion chemistry, flow dynamics, heat transfer and optimal cooling channels design for a given thrust chamber shape. Here the results obtained from the integrated tool have been verified using own computational fluid dynamics results and experimental data as well as the published results available in the literature. Amongst the important parameters, heat transfer rate within the thrust chamber is key design parameter. Here focus is on the prediction of heat transfer rates and surface temperatures of both coolant and thrust chamber. Thus results for the heat transfer rates and heat transfer coefficients are compared with published results, numerical simulations and experimental data. Further calculations for the optimized coolant geometry have been carried out based on the heat transfer, flow rate and pressure drop across the coolant channel. The results indicate that the predicted geometry offers safe operation of the thrust chamber. The integrated tool developed in this study is intelligent enough to optimize a number of coolant channel flow configurations with different coolants and fuels within a short time.