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Under‐ and over‐expanded jet flows are calculated for the Euler equations. The solution procedure is based on the two‐stage Runge‐Kutta time‐stepping scheme. The studies of the flow field structure in diffusers, free jets and impinging jets have been investigated for a range of jet‐to‐stream total pressure ratios and for different exit Mach numbers. The resulting flows show a complex shock‐shear expansion structure with Mach discs. Numerical results are compared with available experimental data and with previously published data. An oscillating phenomenon was observed in the case of free jets operating at sonic exit Mach number and in another case of impingement of under‐expanded jets on a flat plate.

Focuses on the inverse problems arising from the simulation of forming processes. Considers two sets of problems: parameter identification and shape optimization. Both are solved using an optimization method for the minimization of a suitable objective function. The convergence and convergence rate of the method depend on the accuracy of the derivatives of this function. The sensitivity analysis is based on a discrete approach, e.g. the differentiation of the discrete problem equations. Describes the method for non‐linear, non‐steady‐state‐forming problems involving contact evolution. First, it is applied to the parameter identification and to the torsion test. It shows good convergence properties and proves to be very efficient for the identification of the material behaviour. Then, it is applied to the tool shape optimization in forging for a two‐step process. A few iterations of the inverse method make it possible to suggest a suitable shape for the preforming tools.

Unsteady compressible, axisymmetric Navier‐Stokes equations are solved for a flow over a forward facing spike attached to a heat shield for a freestream Mach number range of 1.3‐4.5. A numerical simulation is carried out using a finite‐volume discretization technique in conjunction with a multistage Runge‐Kutta time‐stepping scheme. Comparisons have been made with experimental results such as surface oil flow visualisation, schlieren picture and surface pressure distribution. A good agreement is found between them. Computed results show that lengths of the separated region on the spike are influenced by freestream Mach number. The interaction between the shear layer on the spike and the conical‐reattachment shock wave causes the peak wall pressure and heat flux on the heat shield. The peak heat flux is shown to be a function of freestream Mach number and increases with increase in freestream Mach number.

Social enterprises (SEs), part of the third sector, are hybrid organizations combining the pursuit of social scopes with commercial business solutions. In seeking for social value, they pair for-profit and non-profit features, thereby compensating for shortcomings of both the public sector and the commercial market. Therefore, the performance management of such organizations assumes a crucial relevance. Among the available tools, the balanced scorecard (BSC) aims to capture performance multidimensionality, at the same time fostering legitimacy towards stakeholders.

In general terms, the BSC has the limit to follow a linear and static logic of construction and functioning. For this reason, scholars combine it with system dynamics (SD) to create dynamic balanced scorecards (DBSCs). However, literature seems to devote scarce attention to the adoption of such analytic tools in the third sector, particularly in SEs. This chapter wants to contribute to bridging this gap by proposing a tailored application in the context of a social cooperative, active in the clothing recycle and in the re-integration of disadvantaged social categories. By referring to previous literature about DBSC, two modelling strategies are identified: the BSC-driven and the SD-driven. The latter, based on inductive reasoning, is the one privileged for the study because of its wider flexibility. The modelling outputs consider different perspectives than the ones within traditional BSCs, contain elements of circular causality and show how financial and non-financial performances interplay and co-determine each other. Insights from the proposed model can be useful to support both decision-making and stakeholder engagement.

The purpose of this paper is to design a double parabolic nozzle and to compare the performance with conventional nozzle designs.

The throat diameter and divergent length for Conical, Bell and Double Parabolic nozzles were kept same for the sake of comparison. The double parabolic nozzle has been designed in such a way that the maximum slope of the divergent curve is taken as one-third of the Prandtl Meyer (PM) angle. The studies were carried out at Nozzle Pressure Ratio (NPR) of 5 and also at design conditions (NPR = 3.7). Experimental measurements were carried out for all the three nozzle configurations and the performance parameters compared. Numerical simulations were also carried out in a two-dimensional computational domain incorporating density-based solver with RANS equations and SST k-ω turbulence model.

The numerical predictions were found to be in reasonable agreement with the measured experimental values. An enhancement in thrust was observed for double parabolic nozzle when compared with that of conical and bell nozzles.

Even though the present numerical simulations were capable of predicting shock cell parameters reasonably well, shock oscillations were not captured.

The double parabolic nozzle design has enormous practical importance as a small increase in thrust can result in a significant gain in pay load.

The thrust developed by the double parabolic nozzle is seen to be on the higher side than that of conventional nozzles with better fuel economy.

The overall performance of the double parabolic nozzle is better than conical and bell nozzles for the same throat diameter and length.

The measurement of heat flux is of importance to the development of aerospace engine as basic physical quantities in extreme environment. Heat radiation is one of the basic forms of heat transfer phenomenon. The structure optimizing can improve the performance and infrared absorptivity of the thin film sensor.

This paper designed one kind of thin film heat flux sensor (HFS) with antireflective coating based on transparent conductive oxide thermopile. The introduced membrane structure is so thin that it has little impact on sensor performance. Fabrication of thin film sensors were fabricated by physical vapor deposition (PVD) process.

The steady-state and dynamic response characteristics of the HFS were investigated by calibration platform. The experimental results shown that the absorptivity of the membrane structure (for1070nm) improved compared with that before optimization. The sensitivity of heat flux gauge was 48.56 µV/ (kW/m2) and its frequency response was determined to be about 1980 Hz.

The thin film HFS uses thermopile based on Indium Tin Oxid and In2O3. The antireflective coating is introduced to hot endpoint of HFS to improve sensitivity on laser thermal source. The infrared optical properties of membrane layer structure were investigated. The steady-state and the transient response characteristics of the heat flux sensor were also investigated.

The purpose of this paper is to present an engineering inviscid‐boundary layer method for the calculation of convective heating rates on three‐dimensional non‐axisymmetric geometries at angle of attack.

Based on the axisymmetric analog, convective heating rates are calculated along the surface streamlines which are determined using the inviscid properties calculated on an unstructured grid.

Since the method is capable of using inviscid properties calculated on an unstructured grid, it is applicable to a variety of configurations and it requires much less computational effort than a Navier‐Stokes code. The results of the present method are evaluated on different wing body configurations in laminar and turbulent hypersonic equilibrium flows. In comparison to experimental data, the present results are found to be fairly accurate in the windward and leeward regions.

With this approach, heating rates can be predicted on general three‐dimensional configurations at hypersonic speeds in an accurate and fast scheme.

In order to calculate the heating rates at any specific point on the surface, a technique is developed to calculate the inviscid surface streamlines in a backward manner using the inviscid velocity components. The metric coefficients are also calculated using a new simple technique.

The purpose of this study is to explore the effects of aerospike and hemispherical aerodisks on flow characteristics and drag reduction in supersonic flow over a blunt body. Specifically, the study aims to analyze the impact of varying the length of the cylindrical rod in the aerospike (ranging from 0.5 to 2.0 times the diameter of the blunt body) and the diameter of the hemispherical disk (ranging from 0.25 to 0.75 times the blunt body diameter). CFD simulations were conducted at a supersonic Mach number of 2 and a Reynolds number of 2.79 × 10⁶.

ICEM CFD and ANSYS CFX solver were used to generate the three-dimensional flow along with its structures. The flow structure and drag coefficient were computed using Reynolds-averaged Navier–Stokes equation model. The drag reduction mechanism was also explained using the idea of dividing streamline and density contour. The performance of the aero spike length and the effect of aero disk size on the drag are investigated.

The separating shock is located in front of the blunt body, forming an effective conical shape that reduces the pressure drag acting on the blunt body. It was observed that extending the length of the spike beyond a specific critical point did not impact the flow field characteristics and had no further influence on the enhanced performance. The optimal combination of disk and spike length was determined, resulting in a substantial reduction in drag through the introduction of the aerospike and disk.

To predict the accurate results of drag and to reduce the simulation time, a hexa grid with finer mesh structure was adopted in the simulation.

The blunt nose structures are primarily employed in the design of rockets, missiles, and re-entry capsules to withstand higher aerodynamic loads and aerodynamic heating.

For the optimized size of the aero spike, aero disk is also optimized to use the benefits of both.

The purpose of this paper is to explore the acceptability of an identified staple product enriched with amaranth grain, a traditionally used wild plant familiar to most of the population, after households’ food security status revealed that the majority of them were either at risk or food insecure.

A two-phase non-experimental, quantitative survey design with purposive sampling was used to explore the variety of foods consumed and the food security status of lower skilled (n=63) and higher skilled (n=81) income-earning households. During the second phase, recipe development and sensory acceptance of bread enriched with grain amaranth (n=91) were determined. Descriptive and inferential statistics were used to analyse the data.

Food insecurity was evident among the majority of the lower skilled income households while nearly one in four households in both groups were at risk to become insecure. Daily consumption of chicken and maize meal was evident in lower income households while the frequency in higher income households were significantly less. Bread was found to be the most consumed food product among all households (p=0.001; r=0.455). Supplementation of wheat flour with amaranth flour, a nutritious traditionally familiar wild plant, to support households’ food consumption was investigated. Results from sensory evaluation panels revealed that both bread samples with different percentage of amaranth flour (15 and 25 per cent) were acceptable.

The most important contribution of this study is the re-introduction and incorporation of a traditional food, amaranth, into a modern frequently consumed food to support households’ nutritional and monetary demands to ultimately contribute to general well-being and household food security.