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The purpose of this work is to visualize the flow behaviour in critical sections of a pressurized gating system.

The investigation was carried out using water models of gating system that were designed, invoking the principles of similitude. Water was used as the filling medium, and the manner of flow through various sections of the gating system and the cavity was recorded with a high-speed camera capable of capturing images up to 10,000 frames per second. This was followed by an analysis of the results obtained from each phase. Finally, computer simulations of flow were carried out using commercial software. The manner of filling as observed during experiments and that during simulation were compared so as to draw some useful conclusions on the utility of flow visualization using water models and the capability of software to predict the filling pattern during casting process. It was understood that water models are powerful aids for understanding the intricacies of flow through critical sections of the gating systems.

It was observed that water models are a reliable indicator of the mould-filling process. Further, substantial differences in the filling pattern were observed between water model experiments and filling simulation using commercial software.

The findings are limited to horizontal plate-type castings. Also, the influence of surface roughness in the flow through the runner is not considered.

This work facilitates understanding of the importance of flow visualization on the quality and reliability of castings.

Foundry produces cast metal components and parts for various industries and drives manufacturing excellence all over the world. Assuring quality of these components and parts is vital for the end product quality. The complexity in foundry operations increases with the complexity in designs, patterns and geometry and the quality parameters of the casting processes need to be monitored, evaluated and controlled to achieve expected quality levels.

The literature addresses quality improvement in foundry industry primarily focusing on surface roughness, mechanical properties, dimensional accuracy and defects in the cast parts and components which are often affected by numerous process variables. Primary data are collected from the experts working in sand and investment casting processes. The authors perform machine learning analysis of the data to model the quality parameters with appropriate process variables. Further, cluster analysis using k-means clustering method is performed to develop clusters of correlated process variables for sand and investment casting processes.

The authors identified primary process variables determining each quality parameter using machine learning approach. Quality parameters such as surface roughness, defects, mechanical properties and dimensional accuracy are represented by the identified sand-casting process variables accurately up to 83%, 83%, 100% and 83% and are represented by the identified investment-casting process variables accurately up to 100%, 67%, 67% and 100% respectively. Moreover, the prioritization of process variables in influencing the quality parameters is established which further helps the practitioners to monitor and control them within acceptable levels. Further the clusters of process variables help in analyzing their combined effect on quality parameters of casting products.

This study identified potential process variables and collected data from experts, researchers and practitioners on the effect of these on the quality aspects of cast products. While most of the previous studies focus on a very limited process variables for enhancing the quality characteristics of cast parts and components, this study represents each quality parameter as the function of influencing process variables which will enable the quality managers in Indian foundries to maintain capability and stability of casting processes. The models hence developed for both sand and investment casting for each quality parameter are validated with real life applications. Such studies are scarcely reported in the literature.

Prior literature provides little insight on how management control systems have responded to the growth of collaborative new product development (NPD). The purpose of this paper is to contrast the use of budgets to manage collaborative and in-house NPD and to consider the implications for enabling flexibility.

The paper reports on the findings of a case study company in the medical devices industry that uses two different business models for its NPD activities. While the company engages in in-house NPD for its own products, it also engages in collaborative NPD services with a range of customers.

The study illuminates how two types of budgets (annual and project) can have very different impacts on flexibility under different business models. The annual financial budgets imposed rigid constraints on in-house NPD and resulted in reduced flexibility, whereas in collaborative NPD, they had little impact on flexibility. Project budgets created hard operational constraints in collaborative NPD which generated a highly pressurised yet highly creative environment, whereas project budgets had little impact on flexibility in in-house NPD.

The study contributes detailed empirical insights into the control systems used to manage collaborative NPD from the supplier perspective, where creativity is largely responsive and contrasts these with the management of in-house NPD where creativity is largely expected. The authors also contribute an analysis of the key control systems and other factors that sustain flexibility in this highly pressurised open innovation environment.

The purpose of this paper is to report an experimental study on the effects of various parameters, such as varying flow velocities of water in the pipe, insulating the water pipe, and heating the pipe, to prevent pressurized water in a water hydraulic system from freezing under sub‐zero ambient temperature environment.

An experimental test rig was designed, fabricated, and set up to conduct several experiments to investigate the time taken for water to freeze under sub‐zero ambient temperature at −20°C and with the water initially at a higher temperature than the ambient.

The experiments show that it would take about 90 min for water in the pipe to freeze completely when there is no flow, or water is flowing at slow speed, in the pipe. The results also show that the use of insulation on the pipe would delay the freezing of water inside the pipe; and if used together with heating at several locations on the pipe, freezing of water inside the pipe could be prevented completely.

This paper usefully shows that insulation and heating in a water hydraulic system can prevent freezing of water in the pipe. The promising results of the experimental work mean that water might be able to replace oil in hydraulic systems on aircraft and other low‐temperature applications.

Water systems in civil aircraft, stimulated by passenger comfort needs, have grown to be a comprehensive and important part of aircraft engineering. In this article, following a review of the system types, the design features arc discussed in detail and emphasis has been placed on the functional and hygiene requirements, and on the need for simplicity and weight conservation. Attempts have been made to augment air‐borne water supplies by reclamation means, but these have not been too successful. Investigations should therefore continue into the ways and means of improving the utilization of existing ‘fixed’ capacity systems. Installation safety aspects are also discussed.

THE various systems on the Trident 3B are, as is to be expected, logical developments of those evolved for the Tridents 1, 1E and 2E.

High head gates are commonly used in hydropower plants for flow regulation and emergence closure. Hydrodynamic downpull can be a critical parameter in design of the lifting mechanism. The purpose of this paper is to show that a simplified two-dimensional (2D) computational fluid dynamics solution can be used in the prediction of the downpull force on the gate lip by comparison of computed results to experimentally measured data.

In this study, ANSYS FLUENT CFD software was used to obtain 2D numerical solution for the flow field around a generic gate model located in a power intake structure which was previously used in an experimental study. Description of the flow domain, computational grid resolution, requirements on setting appropriate boundary conditions and methodology in describing downpull coefficient are discussed. Total number of 245 simulations for variable gate lip geometry and gate openings were run. The downpull coefficient evaluated from the computed pressure field as function of gate opening and lip angle are compared with the experimental results.

The computed downpull coefficient agrees well with the previous experimental results, except one gate with small lip angle where a separation bubble forms along the lip, which is responsible from this deviation. It is observed that three-dimensional (3D) effects are confined to the large gate openings where downpull is minimum or even reversed.

In large gate openings, three dimensionality of the flow around gate slots plays an important role and departure from 2D solutions become more pronounced. In that case, one might need to perform a 3D solution instead.

This paper presents a very fast and accurate way to predict downpull force on high head gates in the absence of experimental data.

An extensive amount of simulations are run within the scope of this study. It is shown that knowing its limitations, 2D numerical models can be used to calculate downpull for a wide range of gate openings without the need of expensive experimental models.

THE ESSENTIAL CONTROLLABILITY under hover conditions of the VAK 191B is achieved with hot air ducted from the engine compressor tapping through hot air efflux nozzles. Since the temperature of the air bled from the engine's compressor is at 408°C to 440°C and the pressure range is between 12·2 and 15kgf/cm2 (174 to 215lbf/in2), the differential expansion of the hot air pipes relative to the airframe structure is considerable. There are various means of accommodating hot air pipe expansion and aircraft structure:

AS is to be expected, the various systems on the Trident 2E closely follow those evolved for the Tridents 1 and 1E, except for the changes in the fuel system necessitated by the introduction of the fin fuel tank, and the embodiment of a turbine‐compressor type of cold air unit in the air conditioning system.