Verification in Relevant Environment of a Physics-Based Synthetic Sensor for Flow Angle Estimation

In the area of synthetic sensors for flow angle estimation, the present work aims to describe the verification in a relevant environment of a physics-based approach using a dedicated technological demonstrator. The flow angle synthetic solution is based on a model-free, or physics-based, scheme and, therefore, it is applicable to any flying body. The demonstrator also encompasses physical sensors that provide all the necessary inputs to the synthetic sensors to estimate the angle-of-attack and the angle-of-sideslip. The uncertainty budgets of the physical sensors are evaluated to corrupt the flight simulator data with the aim of reproducing a realistic scenario to verify the synthetic sensors. The proposed approach for the flow angle estimation is suitable for modern and future aircraft, such as drones and urban mobility air vehicles. The results presented in this work show that the proposed approach can be effective in relevant scenarios even though some limitations can arise.

Correlation between the Internal Flow Pattern and the Blade Load Distribution of the Centrifugal Impeller

The blade load distributions reflect the working characteristics of centrifugal impellers, and the vortexes in the impeller channel affect the blade load distribution, but the mechanism of this phenomenon is still unclear. In this study, particle image velocimetry (PIV) was adopted to clarify the correlation between the internal flow pattern and the blade load distribution. The internal flow pattern and the blade load distribution were presented under different working conditions to study the influence of the internal flow pattern on the blade load. Results showed that the vortexes in the flow channel redistributed the blade load. The clockwise vortex made the position of the maximum blade load closer to the outlet, while the counterclockwise vortex had the opposite effect. Meanwhile, the vortexes caused the blade load distribution to be steeper, which reduced energy conversion efficiency. Moreover, the mean absolute flow angle was introduced to explain the mechanism of the effects of vortexes on blade load. The results can be used as a theoretical basis for the design of high-performance impellers.

FORMULASI TABLET HISAP EKSTRAK RIMPANG TEMULAWAK (Curcuma xanthorrhiza Roxb) DENGAN BAHAN PENGISI SORBITOL DAN LAKTOSA

Abstrak Temulawak adalah tanaman yang tumbuh berumpun, yang telah dimanfaatkan oleh sebagian masyarakat Indonesia, baik sebagai obat tradisional, sebagai pewarna maupun sebagai bahan pangan. Perlu dibuat sediaan tablet hisap agar dapat digunakan dengan nyaman dan praktis. Tujuan penelitian ini adalah untuk menguji pengaruh kombinasi bahan pengisi sorbitol dan laktosa terhadap karakteristik granul ekstrak rimpang temulawak dan terhadap mutu fifik tablet hisap ekstrak temulawak. Tablet hisap esktrak rimpang temulawak dibuat dengan campuran bahan pengisi sorbitol dan laktosa dengan konsentrasi berbeda yaitu F1 (sorbitol 5%: laktosa 95%), F2 (Sorbitol 10% dan laktosa 90%), F3 (Sorbitol 15%: Laktosa 85%), F4 (Sorbitol 20% : laktosa 80%), F5 (Sorbitol 25%: laktosa 75%). Tablet dibuat dengan granulasi basah. Penelitian ini menggunakan desain eksperimental laboratorium dengan melakukan pengamatan dan pencatatan hasil dari formulasi tablet hisap ekstrak rimpang temulawak (Curcuma xanthorrhiza Roxb) dengan bahan pengisi sorbitol dan laktosa. Data yang diperoleh dianalisis menggunakan SPSS versi 21 dengan metode ANOVA oneway dengan tingkat kepercayaan 95%. Hasil dari penelitian ini yaitu konsentrasi sorbitol dan laktosa terbaik untuk menghasilkan tablet hisap ekstrak temulawak adalah konsentrasi sorbitol (5%) dan laktosa (95%) dengan kecepatan alir 16,5±0,304 g/detik, persen kompresibilitas 6,57±0,069%, kadar lembab 1,47±0,06%, kekerasan 10,25±0,79 kP. Dari penelitian ini dapat disimpulkan bahwa penambahan konsentrasi sorbitol dapat menurunkan sifat tabletasi dan memperbaiki sifat fisik dari granul, makin tinggi konsentrasi sorbitol kekerasan tablet semakin menurun, dan meningkatkan kerapuhan dan waktu hancur tablet. Sedangkan semakin banyak konsentrasi laktosa meningkatkan sifat alir sudut diam, persen kompresibilitas dan menurunkan kadar lembab. Kata kunci : Temulawak, Tablet hisap, Sorbitol, Laktosa Abstrak Temulawak is a plant that grows in clumps, which has been used by some Indonesian people, both as traditional medicine, as a dye and as a food ingredient. It is necessary to make lozenges so that they can be used comfortably and practically. The purpose of this study was to examine the effect of the combination of sorbitol and lactose as fillers on the granule characteristics of the temulawak rhizome extract and on the physical quality of the lozenges of the temulawak extract. Temulawak rhizome extract lozenges were made with a mixture of sorbitol and lactose as fillers with different concentrations, namely F1 (sorbitol 5%: lactose 95%), F2 (Sorbitol 10% and lactose 90%), F3 (Sorbitol 15%: Lactose 85%), F4 (Sorbitol 20%: lactose 80%), F5 (Sorbitol 25%: lactose 75%). Tablets are prepared by wet granulation. This study used a laboratory experimental design by observing and recording the results of the formulation of lozenges of temulawak rhizome extract (Curcuma xanthorrhiza Roxb) with sorbitol and lactose as fillers. The data obtained were analyzed using SPSS version 21 with the one-way ANOVA method with a 95% confidence level. The results of this study are the best concentrations of sorbitol and lactose to produce lozenges of temulawak extract are concentrations of sorbitol (5%) and lactose (95%) with a flow rate of 16.5±0.304 g/second, percent compressibility 6.57±0.069%, moisture content 1.47±0.06%, hardness 10.25±0.79 kP. From this research, it can be concluded that the addition of sorbitol concentration can decrease the tableting properties and improve the physical properties of the granules, the higher the sorbitol concentration, the lower the tablet hardness, and increase the friability and disintegration time of the tablets. Meanwhile, the more lactose concentration increases the flow angle of repose, the percent compressibility and reduces the moisture content Keywords : Temulawak, Lozenges, Sorbitol, Lactose Keywords : Temulawak, Lozenges, Sorbitol, Lactose

Numerical Analysis on the Crosswind Influence Around a Generic Train Moving on Different Bridge Configurations

In this article, a numerical approach is applied to study the flow regimes surround a generic train model travelling on different bridge configurations under the influence of crosswind. The bridge is varies based on the different geometry of the bridge girder. The crosswind flow angle (Ψ) is varied from 0° to 90°. The incompressible flow around the train was resolved by utilizing the Reynolds-averaged Navier-Stokes (RANS) equations combined with the SST k-ω turbulence model. The Reynolds number used, based on the height of the train and the freestream velocity, is 3.7 × 105. In the results, it was found that variations of the crosswind flow angles produced different flow regimes. Two unique flow regimes appear, representing (i) slender body flow behaviour at a smaller range of Ψ (i.e. Ψ ≤ 45°) and (ii) bluff body flow behaviour at a higher range of Ψ (i.e. Ψ ≥ 60°). As the geometries of the bridge girder were varied, the bridge with the wedge girder showed the worst aerodynamic properties with both important aerodynamic loads (i.e. side force and rolling moment), followed by the triangular girder and the rectangular girder. This was due to the flow separation on the windward side and flow structure formation on the leeward side, both of which are majorly influenced by the flow that moved from the top and below of the bridge structures.

Influence of a rotating nozzle diaphragm on the characteristics of axial low-consumption turbines

Экспериментально исследуются различные компоновки турбинных ступеней с целью обеспечения многорежимности у осевых малорасходных турбин. Определено, что под многорежимностью понимается способность турбины поддерживать величину КПД неизменной, или с небольшими изменениями в достаточно широком диапазоне изменения внешних нагрузок. С новой точки зрения обращено внимание на то, что наиболее выраженными свойствами многорежимности обладают турбины в состав которых входит вращающийся сопловой аппарат. В этой связи рассмотрены авторские результаты экспериментальных исследований биротативных турбин с большим углом поворота потока и двух-ступенчатых осевых турбин с частичным облопачиванием рабочего колеса. Выявлено, у исследованных биротативных турбин свойство многорежимности проявляется при степени парциальности, близкой к единице и регулируется путем изменения соотношения частот вращения соплового аппарата и рабочего колеса. А у одновальных турбин с частичным облопачиванием рабочего колеса свойство многорежимности проявляется в широком диапазоне изменения степени расширения в турбине также при полном подводе рабочего тела. Various arrangements of turbine stages are experimentally investigated in order to ensure multiplicity of operating levels for axial low-consumption turbines. It has been determined that multiplicity is understood as the ability of a turbine to maintain the efficiency value unchanged, or with small changes in a fairly wide range of external loads. From a new point of view, attention is drawn to the fact that the most marked properties of operating levels multiplicity are relevant to the turbines which include a rotating nozzle diaphragm. In this regard, the author's results of experimental studies of birotative turbines with a large flow angle and two-stage axial turbines with partial blading of the running wheel are considered. It was revealed that in the investigated birotative turbines the property of multiplicity is manifested at a degree of partiality close to 1 and is regulated by changing the ratio of the rotation frequencies of the nozzle diaphragm and the running wheel. And in single-shaft turbines with partial blading of the running wheel, the multiplicity property is manifested in a wide range of changes in the degree of expansion in the turbine, also with full supply of the working fluid.

Theoretical Estimation of Minimum and Maximum Allowable Rotational Speed of Supercritical CO2 Inward Flow Radial Turbine

Supercritical CO2 inward flow radial turbines necessitate high operating speeds due to the high density of sCO2, especially in sub-MW scale power generation where rotational speeds can be in the range of 50k to 150k rpm. Although designing the turbine at these high rotational speeds is reasonable from the aerodynamic efficiency point of view but generally not practical to operate. A theoretical framework based on 1-D meanline analysis is built to evaluate the minimum and maximum rotational speed limits corresponding to a set of boundary conditions and operating constraints. The results show that minimum allowable speed depends on the inlet velocity triangle (IVT) and is constrained by inlet Mach number, inlet blade height, and inlet flow angle. On the other hand, maximum allowable speed depends on the outlet velocity triangle (OVT) and is constrained by outlet relative Mach number, outlet hub radius, and blade speed. The theoretical models are demonstrated from kilowatt to megawatt power levels, and the results are compared with commercial software and Balje’s Ns-Ds diagram. Although this study is highlighted in the context of supercritical CO2 as the working fluid, in principle, the same models are equally valid for any working fluid.

Enhanced production from an Air Gap Membrane Distillation Desalination system by varying the feed entry angle

The membrane distillation (MD) process is an evaporative metho driven by the partial pressure difference between two different temperature solutions, namely the hot feed and the coolant. The hot feed evaporates, and the vapour gets condensed to the cooler side. A hydrophobic membrane maintains the evaporating surface. Air Gap Membrane Distillation(AGMD) separates the hot feed from the coolant by a narrow air gap and a coolant plate. The condensate forms on the coolant plate, and the air gap works as an insulation for the heat loss through the membrane. The salient parameters like feed temperature, coolant temperature, and air gap thickness have already been identified through research in previous years. In this study, an innovative technique has been tested to minimize the polarization and increase the production from an AGMD lab-scale unit. The effect of the feed flow entry angle has been investigated. Also, the combined effect of inclined flow entry and a finned coolant surface has been studied. It has been found from the experiments that with a feed flow entry angle of 60°, the system shows an average of 10% to 14% boost in performance. When 60° inlet flow angle and finned coolant plate work in combination, an average of 69% to 78% increase of distillate flux was observed with the same energy input.

Investigation of the effects of main geometric parameters and flow characteristics on secondary flow losses in a turbine cascade

This paper presents numerical simulation results of a three-dimensional (3D) transitional flow in a stator cascade of an axial turbine. The influences of the main geometric parameters and flow characteristics including, the blade aspect ratio, pitch-to-chord ratio, inlet flow angle, and exit Mach number, on secondary flows development and end-wall losses, were studied. The numerical results were validated by the results of experiments conducted in the laboratory of the steam and gas turbine faculty of the Moscow Power Engineering Institute. The maximum difference between computed and experimental results was 2.4 %. The total energy losses decrease by 20 % when the exit Mach number changes from 0.38 to 0.8. Numerical results indicated that the blade aspect ratio had the most effect on secondary flow losses. The total energy losses increase by 46.6 % when the aspect ratio decreases from 1 to 0.25. The total loss of energy by 13.2 % decreases by increasing the inlet flow angle from 60 degrees to 90 degrees. Then by increasing the inlet flow angle from 90 to 110 degrees, the total loss rises by 3.6%. As the pitch-to-chord ratio increases from 0.7 to 0.75, the total energy losses are reduced by 12.2 %. Then by increasing the pitch-to-chord ratio from 0.75 to 0.8, the total energy losses increase by 6 %. As with experimental data, the numerical results showed that the optimal inlet flow angle and relative pitch for the cascade are 90 degrees and 0.75, respectively.

Analysis of surface acoustic wave properties in CaYAl3O7 single crystal

The success on the growth of new piezoelectric materials allows sufficiently increase the operating temperature of the surface acoustic wave (SAW) devices from 300°C to 1000°C. A new calcium yttrium aluminate (CaYAl3O7) single crystal of the tetragonal symmetry has piezoelectric properties up to the temperature of 1000°C. The paper presents a numerical study of the surface acoustic wave properties in the crystal. The SAW velocity, electromechanical coupling coefficient and power flow angle are studied for different crystal cuts of CaYAl3O7. It is shown that the maximum value of SAW coupling coefficient (0.24%) is on the Z+60°-cut and wave propagation direction along the X-axis of the crystal. For the Z-cut and wave propagation direction along the X+45°-axis of crystal, the SAW coupling coefficient is equal to 0.2%. These two cuts of the crystal are potentially useful for SAW device applications.

Study on the Influence of Triangular Groove Structure on Steady-State Flow Force Compensation Characteristics

In this study, a structurally improved spool was designed. The diameter of one side of the spool stem was reduced, making the spool stem into a rounded table shape. A triangular groove was circumscribed on the step and on the same side. After liquid flow was guided through the triangular groove, the flow direction changed. A flow component in the negative direction was generated, which reversely impacted the liquid flow in the positive direction. The liquid flow angle at the outlet increased; that is, jet angle increased and flow force decreased. The simulation results show that, increasing the depth, H, of the triangular groove has a positive effect on flow-force compensation and was conducive to the stability of the valve core. Properly increasing the groove’s bottom diameter, D1, of the triangular groove was conducive to the stability of the spool, but when D1 was too large, the flow force increased. The experimental results are consistent with the simulation results, which proves that the improved structure can effectively reduce the flow force of the spool.