Due to the variable stiffness through their length, their resistance against buckling, damping characteristics due to the friction between their chains, and their small solid length, Volute Springs are widely used in applications where other mechanisms cannot be employed to provide variable Spring stiffness. Meanwhile, the complexities of equations, governing their dramatic non-linear behavior caused the designers to use experimental equations, as well as some simplifications. Therefore, no research has been reported yet that aims to simultaneously optimize the evaluation criteria of these Springs (i. e. their weight and energy conservation capacity) considering their strength, stiffness and natural frequency. In this article providing the governing equations for mechanical behaviors of Volute Springs, the problem of optimized design for this type of Springs are addressed as an optimization problem with its constraints, taking into account the aforementioned goals and considerations. To find a set of Pareto front, an improved version of a multiobjective genetic algorithm is employed, performance of which has been improved, adding a migration operator to a classical NSGA II algorithm. To indicate the proposed method efficiency, a Volute Spring used in a suspension system of a military motorcar was modeled, and its design was optimized. The results show that the functional performance of the designed Volute Spring, such as minimizing the Spring mass and maximizing the stored energy while maintaining design limitations such as dimensions, strength and critical frequency, has been significantly improved.

An optimal design and fabrication of compressors requires flow investigation through the compressor components. Flow field inside the Volute is fully three dimensional and turbulent. Better understanding of flow mechanism leads to improve the Volute design procedure. In this research the experimental and numerical flow investigation through a radial flow compressor Volute are performed to recognize flow field pattern and its effect on pressure loss. The whole compressor components are modeled and the flow field inside the Volute is explored. Numerical studies are verified by measuring the pressures at different cross sections using pressure taps. Flow field investigation through Volute cross sections at different operating range of the compressor is performed utilizing a five-hole probe. The experimental and numerical result differences for Volute total pressure loss prediction are limited and decrease by mass flow rate increase. Flow field measuring results show the flow forced vortex structure at Volute cross section. The effect of diffuser discharge on the fluid field in semi-external Volute cross section is recognized as an extra pressure loss source in addition to creating the non-uniformity in velocity profile.

The Volute of a squirrel cage fan controls the flow .field through the rotor and therefore the complete fan. Performance tests on fans with four rotors of the same diameter but with different widths. Inside two different Volutes showed that larger Volute widths flatten the fan characteristics curve and allow a larger maximum volumetric flow into the fan. When the Volute width is fixed, the performance curves closely overlap and the rotor width only changes the maximum flow rate. The velocity profiles after the rotor were measured using laser Doppler anemometry for four different fans. They show that in each of the four Volute/rotor combinations, the flow out of the rotor is not uniform at different peripheral angles. This pattern changes with Volute width and at different operating conditions. At angular positions closer to fan exit where the cross section is larger and the Volute resistance is smaller, more flow exits the rotor. This flow has a shorter path inside the Volute before it reaches the fan exit and therefore a higher efficiency ensues.

In this study, an impeller and Volute of a centrifugal pump were designed and numerically analyzed in order to improve the pump efficiency. Before design, experimental and theoretical studies were performed on a centrifugal water pump taken as Model Pump (MP). Design parameters were taken as 100 m3/h for volume flow rate, 18m for head and 1480 rpm for rotating speed. After the inspection of the flow field in the MP, some geometrical modifications such as impeller inlet and outlet diameters, blade inlet and exit angles, blade wrap angle, blade thickness, blade inletand exit widthswere realized to design a new pump. Numerical analyses were performed for 8 different volume flow rates overlapping with experimental operation points by Ansys-Fluent Software. In numerical studies, k-ε turbulence model and standard wall function were utilized.The experimental and computational results were compared with the model pump. According to the analysis results at design flow rate, hydraulic torque value is decreased from 56.62 Nm to 51.05 Nm, while hydraulic efficiency is increased from 55.98% to 63.09%. In addition, in order to see the roughness effect and increase the pump efficiency, the wetted surfaces of the impeller and Volute were coated with a polyurethane dye material. Later, performance curves of the coated and uncoated pumps were experimentally obtained which showed that the shaft power of the pump for the coated case was decreased around 10% and the hydraulic efficiency of the pump was increased approximately 18%. According to the economic analysis by basic payback period of the polyurethane coating is less than one year and the internal income ratio for ten-year life-cycle period is around %114.

To research the effect of the Volute geometry on the radial force characteristics of the centrifugal pump during the starting process, choosing a centrifugal pump with a head of 87m as the research object. The pumping chamber is redesigned into a single-Volute and a double-Volute with similar external characteristics, and a circulation pipeline system is established. RNG k-ε turbulence model is employed to calculate the unsteady starting process of two kinds of centrifugal pumps. The variation trends of radial force received by the impeller and Volute during the start-up process are obtained. The radial force characteristics and internal flow field evolution of two centrifugal pumps are compared and analyzed. The results show that the radial force vector distribution of the impeller changes in spiral periodicity during the startup process, and the spiral geometry is influenced by the number of impeller blades. The direction of the spiral is opposite to the rotational speed. The double-Volute geometry can effectively reduce the radial force and pulsation amplitude of the impeller during the start-up process of the centrifugal pump, reducing the radial force by about 80% at rated speed. But the radial force vector distribution of the double-Volute is more complicated and disordered than the single-Volute.

The Research has shown that the primary sound source in centrifugal turbomachines is the blade passing frequency noise, which is caused by due to impac rotor exit flow with the Volute and the wild pressure fluctuations. In this paper, a centrifugal blower with forward facing blades has been selected and the sound created by it in the output channel has been investigated in different operating conditions. Also, to study the relationship between the pressure fluctuations on the Volute and the radiated sound, the amplitude of the pressure fluctuations in different Volutes areas (from the cutt-off to the near-outlet channel) has been investigated. The results show remarkable noise at the blade passing frequency in all fan state modes. It also increases by increasing the fan outlet flow. The pressure fluctuations on the Volute are also evidence of pressure in the blade passing frequency. The intensity of this pressure is reduced far from the Volute tongue, which means that the flow of jet in those areas is lower. Also, at 300 degrees from the cut-off, a strong pressure fluctuation was observed that is the second primary source of the tonal sound (other than the cut-off).

A double-Volute molten salt pump with two outlet pipes is proposed based on the original pump model. A numerical approach coupling finite element analysis and computational fluid dynamics (CFD) is implemented to investigate the operational stability and energy performance of two molten salt centrifugal pumps for high-temperature molten salt. The entropy production of the single-Volute and double-Volute molten salt pumps is investigated. The effects of the Volute structures on the mechanical behavior of the impeller and shaft are considered. According to the findings, the local entropy production in the molten salt pump is dominated by the local pulsating entropy production (Spro-T), with the double-Volute scheme achieving reduced energy loss. A visualization of the flow field and the local entropy production rate (LEPR) distributions indicate that the LEPR is positively correlated with the complexity of the flow, and higher levels of turbulence intensity lead to greater LEPR. The double-Volute scheme enhances the complexity of the flow in the impeller, resulting in an increase in the LEPR compared with the single-Volute design. However, the LEPR in the whole double-Volute molten salt pump is reduced compared with the single-Volute design. It is discovered that the double-Volute molten salt pump experiences a less radial hydraulic force. Although the double-Volute design has a slightly higher maximum equivalent stress on the impeller than the single-Volute scheme, the rotor deformation is significantly less. In general, the double-Volute scheme reduces energy loss and ensures better structural stability.

The rotor-stator interaction between the impeller and the Volute is the main reason for the pump pressure pulsation and vibration. This work aims at designing a new type of tongue to minimize pressure pulsation, reduce vibration noise and energy loss. Inspired by the humpback pectoral fin, four Volute tongues are investigated in this paper, three of which are sinusoidal tubercle Volute tongues (STVT) and one is the original Volute tongue (OVT). Based on the detached-eddy simulation (DES) turbulence model, the influence of the sinusoidal tubercle Volute tongues on the pressure pulsation was investigated, and the flow structure and enstrophy of the four pumps were analyzed, aiming to minimize pressure pulsation, maximize hydraulic performance and reduce the energy dissipation in centrifugal pumps. The results show that the pressure pulsations of the STVT profiles are all lower. The reductions of the average pressure pulsation at the monitoring points are 13. 3% (STVT-1), 20. 6% (STVT-2), and 16. 2% (STVT-3), respectively. The difference in pressure pulsation at the monitoring points closer to the tongue is more obvious. At the design flow rate, the efficiencies of the three bionic pumps are increased by 0. 5% (STVT-1), 1. 5% (STVT-2), 0. 9% (STVT-3), respectively. The STVT profiles change the vortex structure near the tongue and minimized the vortex strength. Meanwhile, the flow in the pump with the STVT profiles have lower enstrophy. The enstrophy of the flow with the STVT-2 profile is the lowest, which is reduced by about 8%. This reduces the dissipation of mechanical energy. The results can be used as a guide for pump design optimization.

Introduction: One of the most difficult procedures in orthodontics is the treatment of skeletal open bite. This malocclusion is characterized by back ward rotation of mandible, an obtuse gonial angle, an increased anterior facial height, and a E long face appearance. The treatment strategy of skeletal open bite has been mainly based on vertical growth inhibition, forward autorotation of mandible, and intrusion of posterior dent alveolar structures. Early treatment of this malocclusion is of great interest because the therapeutic approach is functional before growth has been completed and is surgical afterwards. Posterior bite-blocks are one of the functional appliances which are commonly used. The purpose of this study was to evaluate the effect of Spring loaded posterior occlusal bite block (SLPOBB) on dento-facial structures in patients with skeletal open bite. Materials & Methods: In this clinical trial study, our sample group consisted of 23 skeletal open bite subjects (9 males and 14 females) having a mean age of 9.8, treated by SLPOBB until the open bite was completely dissolved and a favorable overjet was achieved. Cephalometric tracing was carried out on the lateral cephalograms taken prior to and after treatment. The data were analyzed using paired t-test to determine significant changes (a=0.05).Results: Skeletal changes: A statistically significant increase in SNB, ArGoGn, mandible length, anterior facial height, UFH, LFH, and posterior facial height was found.Decrease in ANB, Palatal plane/MeGo, SArGo, SNGoAr, and Y-Axis was also significant. Dental changes: The results revealed a significant increase in Upperl/Palatal plane height, Lower1/GoMe height & Upper 6/Palatal plane height and a decrease in Lower1/GoMe angle. Conclusion: SLPOBB was found to be effective in treatment of skeletal open bite by: 1) A significant decrease of mandibular posterior angles, an increase of posterior facial height, and upward and forward rotation of mandible. 2) Intrusion of mandibular first molars. 3) Extrusion of anterior dentoalveolar height, and lingual inclination of lower incisors.