A theory of the two-dimensional potential flow considering free streamline has been applied to the flow field through a gate valve. From this theory the shape of the separating streamline, contraction coefficient of flow and the critical cavitation number have been obtained. And then by applying the law of momentum to the downstream portion from the gate, the loss coefficient in a gate valve has been estimated. After these theoretical values have been compared with the experimental results on the flow of the squaresection gate valve, it concluded that this theoretical treatment might be regarded as available.

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A miter bend is one of the most general joints of conduits, and it is used in many piping and fluid machinery. So it is very important to industry to clarify flow patterns and mechanisms in a miter bend. Besides, due to the geometrical shape of its conduit the flow in a miter bend separates at the convex corner or the bending corner of the inner wall. So the study of the flow patterns and mechanisms in a miter bend are expected to be useful also in considering general flows with separation. Then, as a basis in considering the flow in the conduit of a miter bend, the authors analyzed the flow with separation at the convex corner of a bending channel in two-dimensional potential flow based upon the hodograph method. The analytical method used in this report can be applied to the bending channel flow with an arbitrary bending angle and an arbitrary crosssectional area ratio. First, for analytical examples of the miter bends with the angles of 45°, 90° and 135°, which are minutely considered in the following reports, the authors analyzed and calculated coefficients of contraction, forms of streamlines and pressure distributions. Next, for those with the angle of 5° and with the angles from 15° to 165° with 15° intervals, the authors calculated the analytical results, and got the relation among bending angles, flow velocities, coefficients of contraction and crosssectional area ratios. Consequently, the following conclusions were obtained-that is, the flow velocities at infinity upstream before bending and cofficients of contraction at the same crosssectional area ratio decrease with the increase of the bending angle; the flow velocities at infinity upstream before bending with the same bending angle decrease but coefficients of contraction increase with the increase of the crosssectional area ratio. In analysis, to suppose potential flow is to ignore the influence of viscous effect. Besides, to suppose two-dimension is to suppose a conduit of rectangular crosssection whose depth is much longer than its width. But it will be clarified in the following reports that with appropriate considerations, the analytical results in two-dimensional potential flow are very useful to the study of the viscous flow in a complicated three-dimensional bend.

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The pressure loss due to flow bending is one of the most important elements showing flow characteristics in a miter bend. But hydraulic or hydrodynamic investigations have not been made sufficiently on the mechanisms of the pressure loss. So in this report its mechanisms are studied by making experiments and considerations on bending flows with different bending angles and crosssectional area ratios. First, the authors observed the flow patterns in bending open channels in laminar flow. Its results showed that the flow in a bending open channel is very complicated with secondary flow, and separation and re-attachment at the convex corner and at the position ahead of the concave corner. Besides, the authors compared the experimental results with the calculated results of streamlines in two-dimensional potential flow, which were reported in the first report, and showed they coincide fairly well. And based on boundary layer theory they calculated the separation point ahead of the concave corner, and showed that its results and the experimental results coincide qualitatively. Next, the authors measured pressure distributions in turbulent flow in miter bend, used for experiments, of rectangular crosssection, which are joined upstream and downstream with long, staight conduits of the same crosssection. And they compared the calculated results in the previous report and the experimental results corrected with pressure loss for friction, and showed that they coincide compartively well when the bending angle is small, but that they differ a little when it is large. Now, they clarified that in actual flow the pressue downstream of the vena contracta after bending increases due to re-attachment and that the stagnation point moves downsteam on the outer wall from the concave corner. Finally, they considered the mechanisms of pressure loss based on the observations of the flow patterns in bending open channels and the experimental results of pressure distributions. Consequently, referring to the experimental results by other researchers, they clarified the pressure loss due to flow bending is the sum of the loss due to sudden contraction and that due to sudden enlargement independently of bending angles, crosssectional area ratios and the shape of the crosssection of a conduit, and so on. The equations for pressure loss calculated thus are correct enough to be used as the empirical formulae for pressure loss in bends.

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It is well known that the rough surfaces absorb more incident radiative energy than the smooth surfaces. In urban regions the surface of the earth is rough due to buildings built on it. Therefore it is expected that in the urban regions the surface of the earth has special absorption properties for solar radiation. It is thought that this speciality of the absorption properties influences on the urban climate. In this paper the absorption properties of the rough surface in the urban regions for solar radiation are discussed. A simple model of the surface of the earth in the urban regions is used to simplify the calculations. The model is the surface on which rectangular parallelpipeds with square horizontal cross sections are laid out regularly at right angles. The absorption properties of the spaces made up of the parallelpipeds decide the properties of the model rough surface. The spaces are called three dimensional cavities for convenience sake. Absorption of sky radiation by the three dimensional cavities is calculated. In the calculation it is assumed that all surface elements of the cavities are gray and have a same absorptivity, a_e, for radiation. The absorptivities of the three dimensional cavities are determined by a_e and the geometries of the cavities, namely, the height of the rectangular parallelpipeds, H, and the transverse and longitudinal intervals between two adjacent parallelpipeds, B and C, when a side of the square cross section is set equal to unity. The calculated absorption properties are compared with those of the two dimensional cavities previously reported by authors. The main conclusions obtained in this paper are as follows: 1) The three dimensional cavities and the two dimensional ones have similar absorption properties. 2) When B=C and H/B remains constant, the absorptivity of the two dimensional cavity is greater than those of the three dimensional ones. 3) When B=C, there is a value of B/C which makes the absorpitivity maximum. The value of B/C is about 0.2. 4) When building to land ratio, namely, 1/(1+B+C+BC), and H are keeped constant, the three dimensional cavities with B=C have the maximum absorptivities and the two dimensional ones (C=0) have the minimum.

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The amount of energy consumption through carrier powers such as fans of air conditioners or chilled or warmed water pumps installed in buildings accounts for nearly fifty percent of the total air conditioning power energy consumed, and constitutes a dominant share of the total energy consumption within buildings. From the same viewpoint, energy conservation or economy of energy pertaining to the carrier system can become one of the important considerations for economizing energy consumption in buildings. The present report gives a full account of the result of our studies made to determine quantitatively to what extent various techniques of saving energy can be good, based chiefly on the patterns of annual energy consumption calculated by computers. Here, energy conservation has been studied with a simulative model building. A summary of the result of our studies follows: 1) Since a large number of hours in operation more than twice that in the case of thermal equipments and partial load operation are the distinctive features of a carrier system, it is necessary, first of all, to discuss an adoption of VAV and VWV systems in order to realize energy conservation with the carrier system. 2) In the case of a water carrier, an open circuit invloves disadvantage with respect to both the capacity to be installed and electric power consumption to be incurred. Since this drawback can be great enough to annual the validity of merits in all other respects making the overall rating the minus in total, a full study on the comprehensive aspects of a system or systems was found necessary. 3) A carrier system of hydraulic line can provide easier access to energy-saving than the carrier system of air line. To put it the other way round, how to render a carrier system energy-conserving can be an important subject of our studies. Although an individual method of reducing the capacity installed, such as in laying out a smaller head loss (pressure loss) or in providing a larger temperature difference, or in adopting an air-recirculating system in lighting appliances, cannot develop a very great effectiveness due to many restrictive conditions affecting each of such items, a respectable overall effectiveness could be achieved, if more of those methods were applied. In this way, it was strongly felt in the course of such studies that designing more energy conserving system is a possibility and anyhow, it will be essential to use care so as not to get involved in non-energy conserving techniques by inadequate designing.

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Recently, numerical method for studies on room air distribution has become of general interest, and the number of related reports is increasing. But, there are many problems which must be solved in order that this method has a practical meaning. The most important one is considered to be that the computational accuracy must be elucidated by comparing the calculated results with the experimental ones. There appear very few reports about this subject. It is well known that we may get accurate solutions only when the change of the dependent variables between adjacent mesh points is nearly linear by usual finite-difference numerical method which approximate the basic governing differential equations. Then the accuracy is presumably very poor in regions where the change of variable is severe as for example turbulent flow near the wall without using very fine mesh spacing. Although the room configuration on which we have calculated in our previous reports, has rather wide supply and exhaust opening in comparison with the room dimension, they must be limited further for simulating the practical room. Again, it is necessary to use very fine mesh spacing in region especially near narrow supply opening, because the change of variables is severe in this region in the same way as in near wall and the calculation often fails to converge with rather coarse mesh in this region which is experienced by authors. It is generally true that in numerical computation of flow field, the means of applying very fine mesh spacing is most effective for improving the accuracy. However, one has to point out at the same time that in the present situation, the available computing machine has limited such performance as capacity and speed of computation. Therefore, the accuracy of calculated results might still not be satisfactory, because from a practical point of view, it is difficult to compute with sufficiently fine mesh spacing and computing time which tend to be very costly. Then it is earnestly necessary at the moment to develop the technique with which one can calculate with practically sufficient accuracy under the conditions of a rather small number of mesh spacing and accordingly a rather short computing time. It is the purpose of this report to describe the improvement which answer these requirement. Improvements are made about following two points, 1) Applying Wall Function proposed by Wolfshtein (1967) for improving the computational accuracy near the wall region. 2) Devising the numerical model for regions near narrow supply opening in comparison with the room dimension for securing computational stability and reasonable accuracy. In this report, we described in detail these two points and compared the calculated results for the room with rectangular section by the improved numerical method to experimental results in respect to flow pattern, temperature distribution and so on. As a result, it becomes clear that the improvement in numerical method gives us statisfactory results, and is a very useful method. The flow is assumed to be two-dimensional, turbulent and not isothermal. We used so-called two-equation models of turbulence which had turbulence energy and viscous dissipation rate of turbulence energy as two dependent variables. This method used in this report is not only one of the many in use, and further investigation is necessary to calculate three-dimensional turbulent room air distribution, but it may indicate the possibility of practical application.

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