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To find the optimal number of channels of rocket engine thrust chamber, it was found that the optimal channel number is 335, at which the cooling effect of the thrust chamber cooling channel reaches the best, which can be helpful to design rocket engine thrust chamber.

The commercial computational fluid dynamics (CFD) software FLUENT with standard k‐ε turbulent model was used. The CFD method was validated via comparing with the available experimental data.

It was found that both the highest temperature and the maximal heat flux through the wall on the hot‐gas side occurs about the throat region at the symmetrical center of the cooling channel. Owing to the strong curvature of the cooling channel geometry, the secondary flow reached its strongest level around the throat region. The typical values of pressure drop and temperature difference between the inlet and exit of cooling channel were 2.7 MPa and 67.38 K (standard case), respectively. Besides an optimal number of channels exist, and it is approximately 335, which can make the effect of heat transfer of cooling channels best with acceptable pressure drop. As a whole, the present study gives some useful information to the thermal design of liquid rocket engine thrust chamber.

More detailed computation and optimization should be performed for the fluid flow and heat transfer of cooling channel.

A very useful optimization on heat transfer and fluid flow in cooling channel of liquid rocket engine thrust chamber.

This paper provides the performance of optimization on heat transfer and fluid flow in cooling channel of liquid rocket engine thrust chamber, which can make the effect of heat transfer of cooling channels best with acceptable pressure drop. As a whole, the present study gives some useful information to the thermal design of liquid rocket engine thrust chamber.

Heat and fluid flow through a trapezoidal cooling chamber were studied numerically. Hot fluid is assumed inflow at some depth below the surface into one end of the chamber and withdrawn at another depth from the other end. The top of the chamber is exposed to the surrounding for cooling and the remaining side‐walls are all insulated. Inflow Reynolds number Ro considered is in the range of 100 to 1000 and the inlet densimetric Froude number Fo considered is in the range of 0.5 to 50.0. Numerical experiments show that the flow and temperature fields in the flow‐through trapezoidal chamber are strong function of both Fo and Ro. The submergence ratio D/do, chamber length to depth ratio L/D and chamber wall angles are also significant in influencing the flow fields. Comparisons were also made with available experimental and prototype data.

The purpose of this paper is to experimentally and numerically investigate the cooling performance of the air-to-water thermoelectric cooling system under different working conditions.

An air-to-water thermoelectric cooling system was designed and manufactured according to the principle of discrete binary thermoelectric Peltier modules, and the thermal performance, heat transfer rate and average COP values were examined at different cooling water temperatures and voltages applied. Additionally, numerical simulations were performed by computational fluid dynamics approach to investigate the temperature distribution and airflow structure inside the cooling chamber.

Analyses were performed using experimental tests and numerical methods. It was concluded that, by decreasing the cooling water temperature from 20 to 5 °C, the average COP increases about 36%. The voltage analysis showed that the efficiency of the system does not always increase as the voltage rises; more importantly, the optimum voltage is different and depends on whether it is desired to increase COP or increase the cooling rate.

In the studies published in the field of thermoelectric cooling systems, little attention has been paid to the voltage applied and its relationship to other operating conditions. In most cases, the tests are performed at a constant voltage. In this study, several options, including applied voltage and cooling water temperature, were considered simultaneously and their effects on performance have been tested. It was found that under such studies, optimization work should be done to evaluate maximum performance in different working conditions.

The purpose of this study is to investigate structure parameters that influence the mixing process of droplets-gas in underwater depth-adjustable launcher cooling chamber and help engineers who design the launcher to distinguish the most important factor that impacts mixing performance in the cooling chamber.

Euler–Lagrangian droplet tracking method was used to simulate droplets-gas mixing process in the cooling chamber. The SST k-w model was adopted to simulate turbulence. Droplet breakup was described by KHRT hybrid model using modified contains which are more fit to the supersonic main flow condition.

The results show the counter-rotating vortex pairs which caused by injected liquid accelerate the mixing process. High-pressure supersonic freestream makes the liquid jet break into more small droplets due to the high momentum of the main stream. Axial injection angle has the greatest influence on Sauter mean diameter (SMD). Penetration height, SMD and total pressure loss slightly change in different tangential injection conditions. However, mixedness decreases with reduction of tangential injection angle due to a more limited space for spray developing. Enlarging orifice diameter raises penetration and mixedness greatly, while SMD and total pressure loss increase slightly.

The findings of this study confirm the key structure parameter to improve mixing performance in the cooling chamber. Engineers who design the underwater depth-adjustable launcher can refer the findings in this study to make control of launching power more accurate.

The purpose of this paper is to describe the design and construction of a custom‐built low‐cost thermal vacuum chamber (TVC) for spacecraft environmental testing and verification. The paper provides detailed analysis and an insight into the design and development of the chamber. The chamber was specifically constructed for carrying out the thermal and vacuum environmental tests in a 16″ dia × 16″ long horizontal thermal vacuum chamber. The chamber is constructed using a combination of mechanical (roughing) pump and turbo‐molecular pump, used to pump the chamber down to 10⁻⁵ Torr and a combination of radiation heaters and nitrogen gas is used to vary the temperature within the chamber from +80 to −50°C.

The TVC equipment is built as part of the picosatellite and nanosatellite program at Space Systems Research Laboratory of Saint Louis University. The equipment is built at a low cost and is suited for testing an entire picosatellite and several components and subsystems of nanosatellite simulating thermal and vacuum conditions similar to space environment. The different main parts of the equipment are described in a way which explains the choice of construction and partly makes it possible to replicate similar equipment.

The TVC equipment is successfully used to simulate the thermal and vacuum conditions of space similar to the conditions experienced by a picosatellite or nanosatellite in low earth orbit.

The design and construction of TVC in this paper have broader implications and can be a platform for future research on low‐cost TVC. This equipment can be utilized in the research areas of electronics and communications, biology and medicine to name a few. Thermal and vacuum experiments on several astro‐biological experiments can be performed.

The paper is intended to be a source of inspiration for industrial or academic space research laboratories which would like to design and construct a similar test‐equipment, instead of investing expensive commercially available alternatives.

The paper discusses in detail, the simplified cost‐effective approach of constructing TVC and also outlines the various issues to be considered. The TVC equipment is custom‐built and is described in an easily understandable way, which makes this a helpful paper for those who wish to produce similar equipment. This will be the only known manuscript in the literature to detail the design and construction of low‐cost, economical TVC.

The purpose of this paper is to review the various pre-processing and post-processing approaches used to ameliorate the surface characteristics of fused deposition modelling (FDM)-based acrylonitrile butadiene styrene (ABS) prototypes. FDM being simple and versatile additive manufacturing technique has a calibre to comply with present need of tailor-made and cost-effective products with low cycle time. But the poor surface finish and dimensional accuracy are the primary hurdles ahead the implementation of FDM for rapid casting and tooling applications.

The consequences and scope of FDM pre-processing and post-processing parameters have been studied independently. The comprehensive study includes dominance, limitations, validity and reach of various techniques embraced to improve surface characteristics of ABS parts. The replicas of hip implant are fabricated by maintaining the optimum pre-processing parameters as reviewed, and a case study has been executed to evaluate the capability of vapour smoothing process to enhance surface finish.

The pre-processing techniques are quite deficient when different geometries are required to be manufactured within limited time and required range of surface finish and accuracy. The post-processing techniques of surface finishing, being effective disturbs the dimensional stability and mechanical strength of parts thus incapacitates them for specific applications. The major challenge for FDM is the development of precise, automatic and controlled mass finishing techniques with low cost and time.

The research assessed the feasibility of vapour smoothing technique for surface finishing which can make consistent castings of customized implants at low cost and shorter lead times.

The extensive research regarding surface finish and dimensional accuracy of FDM parts has been collected, and inferences made by study have been used to fabricate replicas to further examine advanced finishing technique of vapour smoothing.

THE rocket motor is a form of jet propulsion which is characterized by independence of the external atmosphere for combustion, relative independence of altitude and flight velocity upon thrust, small frontal area for high thrusts, simple construction and low weight, and high rate of fuel consumption. Its use was greatly developed during the war years and many applications are now familiar to all. Most of the work on rocket missiles, such as the anti‐aircraft barrages, fighter armament, etc., was performed with solid fuel rockets, but liquid fuels were developed by the Germans for the well‐known V.2, for the Me. 163 aircraft, the Henschel glide bomb and various other applications. They concentrated a great deal of effort on this work and considerable technical progress had been made with different systems. Three main systems emerged and these were distinguished by the oxygen bearing fluids they used. The fluids were:

Rapid tooling (RT) integrated with additive manufacturing technologies have been implemented in various sectors of the RT industry in recent years with various kinds of prototype applications, especially in the development of new products. The purpose of this study is to analyze the current application trends of RT techniques in producing hybrid mold inserts.

The direct and indirect RT techniques discussed in this paper are aimed at developing a hybrid mold insert using metal epoxy composite (MEC) in increasing the speed of tooling development and performance. An extensive review of the suitable development approach of hybrid mold inserts, material preparation and filler effect on physical and mechanical properties has been conducted.

Latest research studies indicate that it is possible to develop a hybrid material through the combination of different shapes/sizes of filler particles and it is expected to improve the compressive strength, thermal conductivity and consequently increasing the hybrid mold performance (cooling time and a number of molding cycles).

The number of research studies on RT for hybrid mold inserts is still lacking as compared to research studies on conventional manufacturing technology. One of the significant limitations is on the ways to improve physical and mechanical properties due to the limited type, size and shape of materials that are currently available.

This review presents the related information and highlights the current gaps related to this field of study. In addition, it appraises the new formulation of MEC materials for the hybrid mold inserts in injection molding application and RT for non-metal products.

This paper aims to focus on the changes in thermal and surface characteristics of acrylonitrile butadiene styrene (ABS) material when exposed to chemical vapours for surface finishing. The poor surface finish and the dimensional accuracy of the fused deposition modelling parts (of ABS material) because of the stair-stepping hinder their use for rapid tooling applications, which can be improved by vapour finishing process. The differential scanning calorimetry (DSC) tests are performed to investigate the thermal behaviour of ABS thermoplastic after vapour finishing.

The hip prosthesis replica has been used to highlight the efficacy of chemical finishing process for intricate and complex geometries. The replicas are treated with chemical vapours for different durations. The DSC tests are performed along with surface roughness, surface hardness and dimensional measurements of exposed replicas and compared with unexposed replica.

The longer finishing time, i.e. 20 s, manifested higher melting peak temperature, higher melting enthalpy and higher heat capacity along with smoother and harder surface as compared with unexposed replica. The finishing process enhanced the bonding strength and the heat-bearing capacity of ABS material. The vapour finishing process enhanced the thermal stability of the material which may extend its sustainability at higher temperatures.

The improved thermal stability of ABS thermoplastic after chemical vapour finishing has been demonstrated. This advancement allows the use of ABS in functional tooling suitable for small production runs with higher flexibility and lead time savings.

The heat effects associated with phase transitions as a function of temperature are studied in case of replicas finished with chemical vapours. The relationship between melting enthalpy and surface characteristics has been ascertained.

B. O. Morris Ltd. have announced the release in U.K. of a new Grasso Pneumatic Hammer, the H.17, operating at 4,000 strokes/min.