unglazed transpired solar collectors are widely used for heating outside air directly, these days. pre-heating ventilation air for large spaces and heating air for crop drying, are some of the applications of these kinds of collectors. the outside air is drawn straight from ambient, uniformly through the whole surface of a perforated absorber (transpired, dark-colored plate) exposed to the sun....

Using two-dimensional hydrodynamical simulations, we investigate the interaction of a collimated fast wind (CFW) interacting with a spherical asymptotic giant branch (AGB) wind as the mechanism for shaping proto-planetary nebulae and young planetary nebulae. In particular, we compare our simulations to the observations of an evolved PPN with multiple, highly collimated lobes, CRL 618. We charac...

As a wind turbine extracts energy from the wind, induced wind velocities, lower than the freestream velocity, will be present both upstream and downstream of the rotor. In this study, the upstream induction zone of a 225 kW horizontal axis Vestas V27 wind turbine located at the Danish Technical University’s Risø campus is investigated using a scanning Light Detection and Ranging (lidar) system....

Retrieval of wind fields from a single-Doppler lidar with small azimuthal sectors is challenging. Both simpler retrieval algorithms such as Velocity Azimuth Display (VAD) or Volume Velocity Processing (VVP), and more sophisticated techniques such as Four Dimensional Variational Analysis (4DVAR) using VAD for mean velocities have limitations on small sectors of data. Narrow datasets may result i...

A mathematical model is used to simulate the effect of wind conditions on men's and women's 200-m times. Four questions are posed: What is the effect of constant winds on 200-m performance? What is the effect of varying wind speed and direction? What is the effect of the lane allocation? How do wind conditions affect the velocity profile? The race is simulated for winds with constant velocity a...

According to the shortcomings of the existing ultrasonic wind velocity measurement device, for instance, complexity of circuit and difficulty of signal processing, a new ultrasonic wind velocity measurement is put forward based on phase discrimination and a new sensor configuration as well. Thus, a system model is built. Firstly, an equilateral triangle should be constituted by an ultrasonic em...

Building integrated photovoltaic/thermal (BIPV/T) systems serve two purposes – generate electricity and heat ambient air using absorbed solar energy. High wind velocity reduces the efficiency of unglazed transpired solar collectors (UTC). Indeed, wind flow on the collector’s surface reduces the useful heat transferred to the plenum air by effectuating convection losses and suction in the pores;...

the natural ventilation is an easy way to exchange the indoor polluted warm air with outdoor fresh air. the wind power injects outdoor fresh air into the building. a good indoor air current and subsequently a proper exhaust depend on the openings’ conditions and their situations. a serious architectural question is under what conditions of the openings the wind-cross ventilation can be effectiv...

the study of interactions of jet into cross flow at different longitudinal and transverse angles ofjet was studied. the following components were designed and constructed: a low velocity windtunnel to produce the uniform flow, a flat plate with a traverse injection system to simulate the jetinjection, and a spatial rake to measure the total pressure. the tests were carried out atlongitudinal (α...