This paper aims to present the experimental result obtained from dynamic response on flee-flee beam in driving point and transfer mobility analysis using impact test method using hammer tips that are steel, plastic an...This paper aims to present the experimental result obtained from dynamic response on flee-flee beam in driving point and transfer mobility analysis using impact test method using hammer tips that are steel, plastic and rubber. The 8630C accelerometer and analyzer is used for data logging and for the analysis, the plastic hammer tip is chosen. The analytical and the experimental value then are compared for the free-free beam natural frequency, damping ratio, and stiffness value. As a result, the highest percentage error for natural frequency is approximated to 2.7%, the damping ratio is approximated to 3.115 × 10^-3 and the stiffness value gives the major different between the experiment value and theoretical value. Finally, this method can be used to determine the properties of a structure such as natural frequency, mode shapes, damping ration and stiffness, respectively.展开更多
This research proposes a new theory in the field of physics and space technology, based on several scientific hypotheses and conclusions, as it plans to manufacture a “new magnetic focus” by means of high-speed cent...This research proposes a new theory in the field of physics and space technology, based on several scientific hypotheses and conclusions, as it plans to manufacture a “new magnetic focus” by means of high-speed centrifugal engines, by equipping a group of them, and installing heavy, dense fans, not for the purpose of air pressure, Rather, it works to rotate at a speed of up to 1000 kilometers per hour at an angle of 45 degrees, and is lined up in front of each other in a circle, so that the final result is to transfer the effort and weight of the propellers to an upper point in their midst, and this point will reach a large degree of density, size and mass, causing the generation of a point independent magnetic attraction, which pulls the motors upward, as a result of the mutual gravitational effect created by the motors. These hypotheses need a large number of experiments, applications, and analyze the use of specialists in physics, technology, technology, engine engineers, and others, and the correct results will cause a major revolution in the field of space technology, and this theory will be relied upon in many means of land, air, and space transportation and different fields.展开更多
The performance of a turbulent air jet impinging on a flat surface and subjected to cross flow is investigated.The study considers many different parameters,including Reynolds number Re,the normalized orifice-to-targe...The performance of a turbulent air jet impinging on a flat surface and subjected to cross flow is investigated.The study considers many different parameters,including Reynolds number Re,the normalized orifice-to-target spacing Z/D,and the ratioαof cross-flow to jet Reynolds numbers.As reported by other investigators,the optimum value of Z/D is 6.At this optimum Z/D,when the Reynolds number is raised from 5100 to 23000,the stagnation Nusselt number Nu increases by 150%.A correlation is proposed to estimate stagnation point heat transfer.Velocity profiles are used to examine the cooling characteristics of jets with and without cross flow.Cooling in both the upstream and downstream regions is estimated and compared with the performance of a jet without cross flow.For Z/D=6,the stagnation Nu decreases by 84%whenαis increased from 0 to 2.The corresponding decrease in the stagnation Nu for Z/D=2 is 75%.Cross flow significantly affects the flow pattern of fluid near the target surface,and anomalous flow behavior is observed in the stagnation region.Without cross flow,the radial velocity is close to zero at r/D=0,and the fluid velocity increases in the outward direction and attains a maximum value at r/D=1.With cross flow,the position of the peak velocity shifts.Average,stagnation point,and peak heat transfer coefficients are discussed in terms of the Stanton number.At low values ofα,there is an increase in the peak Nu.With cross flow,the location of the peak velocity changes.The augmentation in cooling in the downstream region and the reduction in cooling in the upstream region depend strongly on Z/D andα.For Z/D=2,atα=1,the average heat transfer downstream increases by 15%and the corresponding decrease upstream is 35%.展开更多
文摘This paper aims to present the experimental result obtained from dynamic response on flee-flee beam in driving point and transfer mobility analysis using impact test method using hammer tips that are steel, plastic and rubber. The 8630C accelerometer and analyzer is used for data logging and for the analysis, the plastic hammer tip is chosen. The analytical and the experimental value then are compared for the free-free beam natural frequency, damping ratio, and stiffness value. As a result, the highest percentage error for natural frequency is approximated to 2.7%, the damping ratio is approximated to 3.115 × 10^-3 and the stiffness value gives the major different between the experiment value and theoretical value. Finally, this method can be used to determine the properties of a structure such as natural frequency, mode shapes, damping ration and stiffness, respectively.
文摘This research proposes a new theory in the field of physics and space technology, based on several scientific hypotheses and conclusions, as it plans to manufacture a “new magnetic focus” by means of high-speed centrifugal engines, by equipping a group of them, and installing heavy, dense fans, not for the purpose of air pressure, Rather, it works to rotate at a speed of up to 1000 kilometers per hour at an angle of 45 degrees, and is lined up in front of each other in a circle, so that the final result is to transfer the effort and weight of the propellers to an upper point in their midst, and this point will reach a large degree of density, size and mass, causing the generation of a point independent magnetic attraction, which pulls the motors upward, as a result of the mutual gravitational effect created by the motors. These hypotheses need a large number of experiments, applications, and analyze the use of specialists in physics, technology, technology, engine engineers, and others, and the correct results will cause a major revolution in the field of space technology, and this theory will be relied upon in many means of land, air, and space transportation and different fields.
文摘The performance of a turbulent air jet impinging on a flat surface and subjected to cross flow is investigated.The study considers many different parameters,including Reynolds number Re,the normalized orifice-to-target spacing Z/D,and the ratioαof cross-flow to jet Reynolds numbers.As reported by other investigators,the optimum value of Z/D is 6.At this optimum Z/D,when the Reynolds number is raised from 5100 to 23000,the stagnation Nusselt number Nu increases by 150%.A correlation is proposed to estimate stagnation point heat transfer.Velocity profiles are used to examine the cooling characteristics of jets with and without cross flow.Cooling in both the upstream and downstream regions is estimated and compared with the performance of a jet without cross flow.For Z/D=6,the stagnation Nu decreases by 84%whenαis increased from 0 to 2.The corresponding decrease in the stagnation Nu for Z/D=2 is 75%.Cross flow significantly affects the flow pattern of fluid near the target surface,and anomalous flow behavior is observed in the stagnation region.Without cross flow,the radial velocity is close to zero at r/D=0,and the fluid velocity increases in the outward direction and attains a maximum value at r/D=1.With cross flow,the position of the peak velocity shifts.Average,stagnation point,and peak heat transfer coefficients are discussed in terms of the Stanton number.At low values ofα,there is an increase in the peak Nu.With cross flow,the location of the peak velocity changes.The augmentation in cooling in the downstream region and the reduction in cooling in the upstream region depend strongly on Z/D andα.For Z/D=2,atα=1,the average heat transfer downstream increases by 15%and the corresponding decrease upstream is 35%.
