Permeability and porosity of woolen fabrics are investigated experimentally in this paper. Permeability experiments are conducted in a wind tunnel to the TS 391-EN ISO 9237 standard. Woolen fabric is placed in the test section of the wind tunnel to measure permeability to airproofing . Velocity measurements are made used a hot wire anemometer in the front and rear of the wool. Air permeability is closely related to pore size and distribution. So, it is important to study porosity, in order to classify and determine the right use of woolen fabrics. Many methods are used to estimate porosity. In this study, the theoretical model is used for determination of porosity values, and the influence on porosity of various fabric parameters was investigated. Depending on the permeability, weft and warp density, weight, fabric thickness and porosity relationship are investigated. The results are presented as graphs.

SUMMARYThe proper optimization criterion to be chosen for the optimum design of the heat engines may differ depending on their purposes and working conditions. In this study, a comparative performance analysis is carried out for a reversible Otto cycle based on three alternative performance criteria namely maximum power (mp), maximum power density (mpd) and maximum efficient power (mep). The power density criterion is defined as the power per minimum specific volume in the cycle and the efficient power criterion is defined as multiplication of the power by the efficiency of the Otto cycle. Maximizing the efficient power gives a compromise between power and efficiency. Three different objective functions are defined and maximization of these functions is carried out under different design parameters of the Otto engine. The variations of power, power density and efficient power outputs are derived and presented with respect to the thermal efficiency of the cycle for various temperature ratios. It has been found that the design parameters at mep conditions lead to more efficient engines than that at the mp condition and the mep criterion may have a significant power advantage compared with mpd criterion.

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In this study, an exergy optimization has been performed for a cogeneration plant consisting of an irreversible Carnot heat engine. In the analysis, different objective functions have been defined based on alternative performance criteria and the optimum values of the design parameters of a cogeneration cycle were determined for different criteria. In this context, the effects of irreversibilities on the exergetic performance are investigated, and the results are discussed. List of SymbolṡE Exergy ratė Q Rate of heat transfer I Irreversibility parameter R Power to process heat ratio S Entropy T Temperaturė W Power generated from the cogeneration system M. Atmaca (B) · M. Gumus · A. T. Inan

In recent years, the use of unmanned aerial vehicles has increased rapidly. These vehicles have instant detection, tracking and destruction capabilities in military operations. In addition, when compared other conventional aerial vehicles, in the case of the vehicles down, any loss of driver life can be accounted for the most important factor in the view of widespread use of this vehicle. It is very important to make aerodynamic analyzes of unmanned aerial vehicles swarming behavior and to identify reliable zones for vehicles. It should be determined at what speeds and closeness of the flying vehicles along the specified routes the vehicles should be located within the frame. In this study, the models of an unmanned aerial vehicle and propellers of an UAV were designed with computational fluid dynamics. Especially turbulence, pressure, and speed changes have been investigated. Moreover, the range of interaction distance that they can create on each other is determined and reliable regions are determined.

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