Tesla Turbine Research Articles

Identifying and mitigating energy losses in Tesla turbines: A study on CFD optimization

AbstractThis study investigates the flow dynamics and energy losses of Tesla turbines using Computational Fluid Dynamics with OpenFOAM. Our goal is to identify the main sources of energy loss. Four main sources of energy loss were identified. The most significant loss occurred during the conversion of pressure energy to kinetic energy, estimated to range from to of the total energy. Energy losses due to leaks between the rotor and the casing were also quantified, ranging from to of the kinetic energy at peak efficiency points. Design modifications, such as incorporating a nozzle at the entrance of the turbine, can improve efficiency. These findings highlight specific areas for efficiency improvement, offering opportunities for improved turbine design and integration into energy‐generation systems.

Application of roughness models to stationary and rotating minichannel flows

PurposeThe performance of a bladeless Tesla turbine is closely tied to momentum diffusion, kinetic energy transfer and wall shear stress generation on its rotating disks. The surface roughness adds complexity of flow analysis in such a domain. This paper aims to assess the effect of roughness on flow structures and the application of roughness models in flow cross sections with submillimeter height, including both stationary and rotating walls.Design/methodology/approachThis research starts with the examination of flow over a rough flat plate, and then proceeds to study flow within minichannels, evaluating the effect of roughness on flow characteristics. An in-house test stand validates the numerical solutions of minichannel. Finally, flow through the minichannel with corotating walls was analyzed. The k-ω SST turbulent model and Aupoix's roughness method are used for numerical simulations.FindingsThe findings emphasize the necessity of considering the constricted dimensions of the flow cross section, thereby improving the alignment of derived results with theoretical estimations. Moreover, this study explores the effects of roughness on flow characteristics within the minichannel with stationary and rotating walls, offering valuable insights into this intricate phenomenon, and depicts the appropriate performance of chosen roughness model in studied cases.Originality/valueThe originality of this investigation is the assessment and validation of flow characteristics inside minichannel with stationary and corotating walls when the roughness is implemented. This phenomenon, along with the effect of roughness on the transportation of kinetic energy to the rough surface of a minichannel in an in-house test setup, is assessed.

Extended analytical model of Tesla turbine with advanced modelling of velocity profile in minichannel between corotating disks with consideration of surface roughness

Consideration of roughness effects in the flow in a minichannel has been a major scientific problem for many decades. Roughness can alter the momentum diffusion, heat transfer conditions or laminar-turbulent transition. These effects are even more pronounced in minichannel flows where the roughness can occupy a large part of the cross-section. Modelling methods applied so far usually fall short in internal flows with high relative roughness. The presented paper pertains to the analytical flow model in Tesla turbine components with consideration of roughness on the rotor walls. The model uses the equivalent sand grain approach to modify dynamic viscosity in the governing equations to achieve a desired downward shift of the dimensionless velocity profile. The model solves two-dimensional equations of continuity, momentum and energy. The semi-empirical function was derived to consider the change in the shape of the radial velocity. The applied model incorporates Euler's turbomachinery equation to determine the influence of roughness on the turbine performance under varied operating conditions. Roughness shortens the streamlines inside the rotor, but the overall turbine's performance is improved. The roughness equal to 10−5 m increased the power generated and isentropic efficiency by factors of 3 and 2.5, respectively, compared to the smooth rotor.

Analytical Analysis of the Bladeless Rotor Turbine Design for Enhanced Performance

The growing desire for clean and efficient energy solutions has fueled considerable advances in turbine technology. This study proposed a conceptual approach to enhancing the performance of bladeless turbines using an analytical technique, and the analytical solutions bear a resemblance to the experimental setup for a fluid dynamics investigation of a rotor for real-flow effects. The Navier-Stokes equations for fluid flow in cylindrical coordinates were simplified to two-dimensional flow by ignoring axial direction and velocity, and direct integration was used in conjunction with series expansion solutions. The experiment data were used to verify the rotor's fluid dynamics analytical solutions. The model's result was compared to previously calculated solutions of the fluid dynamics of a disc rotor in a bladeless turbine. The disc turbine models were used to predict radial velocity, tangential velocity, pressure gradient, volumetric flow rate, rotor torque, shear stress on the inner and outer disc walls, and rotor efficiency. The model was validated using experimental data with an efficiency of 23.9%, the theoretical solution model was 34%, and the analytical efficiency was 24.3%. The efficiency comparison of the analytical solutions model to the theoretical solutions model revealed a substantial difference, however, the correlation between computed theoretical and analytical results is significant. Previous studies used computed solutions for models, but current analytical solutions outperformed them. The model's output will be valuable to engineers building the disc turbine. It demonstrates a strong link between the analytical and experimental research of the bladeless turbine.

An experimental investigation of a solar chimney integrated with a bladeless wind turbine for sustainable energy harvesting

The current study explores the potential of combining small-scale solar chimney systems with blade-less wind turbines for sustainable energy solutions in Egypt through mathematical modelling, numerical simulation, and experimental work. The integration of a vortex bladeless turbine and a conventional horizontal axis wind turbine in a hybrid energy harvester solar chimney system (VBSCS) was evaluated, as well as the effect of changing the absorber material on improving the system's performance. Shredded rubber improves heat absorption in solar chimney collectors, optimizing energy conversion and providing a sustainable, eco-friendly solution while addressing challenges and cost-effectiveness in implementing this hybrid solution. The mathematical model predicted the highest power at 0.38 W, while the CFD model yielded 0.298 W. Experimental results showed power outputs of 0.18 and 0.25 W for the SCS with concrete and shredded rubber absorbers, respectively. In addition, the VBSCS with a concrete absorber produced 0.29 W. The determined percentage improvement over the SCS with a concrete absorber was 61.1 % for the VBSCS and 38.9 % for the SCS with a black rubber absorber. These findings demonstrate the delicate interplay of design aspects and material choices that influence the performance of both bladeless wind turbines and solar collector systems.

Design of a New Supersonic Shock Wave Generator and Application in Power Generation

Wind energy is a kind of renewable energy with great potential for development. This study mainly investigated the application of shock waves generated by high-pressure gases (wind energy) for generating energy. In this study, we designed a new supersonic shock wave generator that can be reused without disassembling and assembling bolts and developed a shock wave monitoring system. It could measure the velocity of the generated shock waves at about Mach 3–5, and the output pressure exceeded 900 kg/cm2 (more than 100 times the input pressure). Then, we developed a power generation system driven by supersonic shock waves based on the characteristics of the new shock wave generator, which could generate high-pressure and high-speed blast waves and could be reused. The shock wave generator can repeatedly generate high-pressure waves to drive the Tesla turbine and then rotate the magnetic energy generator for power generation. This paper used tank pressure, output pressure, gas flow, rotation speed, voltage, and current detected by the system to conduct power generation performance analysis. When the minimum rotation speed was set to 1500 rpm and three bulbs were turned on as loads, the system could generate an average voltage of 36.64 V and an average current of 211.01 mA as output (power about 7731.41 mW).

Enhanced Efficiency of Tesla Turbines with Variable Disc Configurations in Indonesia

The rapid development of technology increases the demand for energy while non-renewable sources decline. This study explores the Tesla turbine, which converts fluid energy into mechanical energy using circular discs stacked with specific gaps. We tested three configurations with 4, 6, and 8 discs, each 0.3 mm thick, at Universitas Muhammadiyah Sidoarjo. Using direct observation, experimental testing, and literature review, we measured turbine performance with a digital tachometer and spring scale. Results showed that modifying the disc number effectively influenced energy output, offering insights for enhancing Tesla turbine efficiency as a renewable energy solution. Highlight: Tesla turbine converts fluid energy to mechanical using circular discs. Tested configurations: 4, 6, and 8 discs, each 0.3 mm thick. Study offers insights into enhancing Tesla turbine efficiency Keywoard: Tesla Turbine, Energy Conversion, Fluid Dynamics, Renewable Energy, Disc Configuration

A Practical Design Approach of the Tesla Turbine for Hydro Power Applications

In the global push for harnessing energy in a vast number of scenarios, the Tesla Turbine stands out as a potential niche device in various small-scale applications. This device can be fabricated rapidly, using locally available materials and conventional manufacturing operations. Despite these advantages, several technological challenges have held back the development of the Tesla Turbine. Besides, modern bladed turbines have a much broader range of applications. Another issue is that this turbine’s most recent experiments were focused on numerical tests or findings from the computational simulation. Very few studies that were conducted resulted in low-efficiency ratings. For advanced applications such as particulate flow, biomedical, and some modern machining methods that use abrasive particle-rich fluids, Tesla turbines can also be used as it is not sensitive to mixed fluids compared to conventional bladed turbines. Moreover, the construction cost of a Tesla turbine is meager compared to bladed turbines. Thus, the cost-to-performance ratio is higher than that of conventional turbines, which the authors believe could pose much interest for both further research and development.

Numerical simulation of vortex-induced vibration in a bladeless turbine: Effects of separation distance between tandem harvesters

<p>Bladeless wind turbines are attracting attention as energy harvesters due to several conveniences like the ease of construction and suitability for operating under small wind speed. As a grouped energy generation system, it is likely the simplest configuration compared to wind farms. However, the characterization of tandem harvesters requires a deep understanding of the effects produced by the interaction of the two. Therefore, this work considered a set of two conical cylinders representing tandem harvesters, which lie on the bottom of a wind tunnel and were subjected to resonance conditions. The attention focused on evaluating the effects of separation distance between conical cylinders by three distances: $\ell$ = 0.25<italic>h</italic>, 0.5<italic>h,</italic> and 0.75<italic>h</italic>, where <italic>h</italic> is the cylinder's total height. Oscillation due to vortex shedding was numerically predicted. The analysis centered on the fluid-structure interaction in pairs of wind generators subjected to wind-induced resonance, and how the distance between them affects their oscillation. Experimental data of cylinder vibration measured in a wind tunnel served to validate the numerical results. The results showed strong effects of the wake on the second cylinder placed downstream from the first one for a distance $\ell$ = 0.25<italic>h</italic>. In contrast, minimum effects were observed for $\ell$ = 0.5<italic>h</italic> and $\ell$ = 0.75<italic>h</italic>.</p>

Numerical and experimental investigations on a bladeless turbine: Tesla's cohesion-type innovation

The design, numerical simulation, manufacturing, and physical experimentation of Tesla's bladeless centripetal turbine for electrical power production are the topics of this research project. The turbine generates rotational motion in the discs by directing pressurized air and water tangentially across parallel smooth disc surfaces. The fluid speed parameter at the nozzle inlet determines the power generated. To ensure optimal mechanical design parameters, SolidWorks design software, fluid dynamics concepts, and machine element design were employed. The numerical simulation software ANSYS CFX was used. The numerical and qualitative findings of the models and physical experiments coincided well. The study revealed that the power production and turbine efficiency were regulated by the input sources and blade size. Variations in the fluid composition between the discs may additionally have an impact on the outcomes. The researchers investigated the connection between input fluid pressure and turbine efficiency, as well as the number of discs and turbine power. The prototype could generate 76.52 W of electricity at 50 bar pressure and 1.01e+05 Reynolds number. The operation was efficiently simulated using CFD, with only a 9.3% difference between experimental and simulated results. Overall, this research provides an in-depth assessment of Tesla's bladeless centripetal turbine. It verifies the design and numerical simulation methodologies used, as well as identifies the essential aspects impacting turbine performance and efficiency. The findings contribute to a better understanding of the turbine's behavior and give ideas for improving its performance.

Pengaruh Lubang Dan Jumlah Disk Terhadap Performa Turbin Tesla

This research focuses on the effect of holes and the number of disks on the performance of the Tesla turbine, where this experiment uses one Tesla turbine unit with a constant inflow discharge of 0.037 m3/s and a constant load of 50 kg on. Then testing was carried out by varying the number of holes on the disk (4, 6, 8) and varying the number of disks (11,13, 15) with a hole diameter of 10 mm, disk diameter of 160 mm, disk thickness of 0.5 mm. After testing and data analysis, it can be seen that the variations in the number of holes on the disk (4,6,8) and the number of disks factor can be concluded that the maximum power is 310,148 Watts for the number of holes on the disk factor while for the number of disks factor it is 301,154 Watts, where there is a difference of 8,994 Watts. Meanwhile, the maximum efficiency is 73.754 for the number of holes in the disk, while for the number of disks it is 71.652, where there is a difference of 2.102.
 Keywords : Turbine, Tesla, Disk, Performance

USE OF TESLA TURBINES IN LIGHTING SYSTEMS OF MULTI-STORY RESIDENTIAL BUILDINGS

The energy efficiency of the Tesla turbine of various designs in pico-hydro systems was studied. The reconstruction of the drainage system for the installation of a pico-hydro system is substantiated. The scheme of the pico-hydro system for lighting stai

Performance Investigation of Stator-Less and Blade-Less Radial Expander

Abstract Interests in small-scale turbomachinery are gaining momentum, particularly around waste heat recovery using Organic Rankine Cycle (ORC), energy harvesting, pico-hydro, refrigeration and heat pumps and small-scale power generation. These applications demand to have economical, simple construction, and reasonably efficient machines. The performance of bladed turbomachine at a small scale is poor mainly due to viscous losses and relatively large clearances. In some cases, like ORC, it requires a lubrication system, making it complex and costly. Bladeless or Tesla turbomachinery is seen as one of the solutions for these applications due to its simple construction and cost-effectiveness. However, the experimental efficiency of the bladeless turbines/compressors is found in the low region, <40%. In this article, the performance of a bladeless turbine is investigated using a vaneless volute configuration, making the turbine stator-less (vaneless volute) and bladeless (vaneless rotor). This study presents numerical and experimental performance investigation with a volute as a stator of the bladeless rotor. Three-dimensional (3D) Numerical results show very promising performance of the turbine with total to static efficiencies calculated above 65%. In the second part of the article, turbine prototype components, assembly, and test setup are discussed. Experimental maximum efficiency of 41.5 ± 0.88% at 3.5 kg/s@5000 rpm and power of 915 W is obtained. This is the highest recorded efficiency for the Tesla turbine in peer-reviewed research. The overall turbine performance from 3D numerical simulation with ventilation and mechanical losses is compared with experimental results. This work demonstrates that the proposed stator-less/volute configuration provides an efficient way for bladeless or Tesla turbines, particularly for low-head applications.

Using Tesla turbine for waste heat recovery: Currents status and future directions

Using Tesla turbine for waste heat recovery: Currents status and future directions

Study on the Effects of Individual Pitot Tube Inlet of a Bladeless Tesla Microturbine using Numerical Analysis

In this paper, a comprehensive numerical analysis of a bladeless Tesla microturbine is presented. Various studies on the effects of Tesla design parameters have shown promising results. However, the limitations associated with the inherent nozzle design have often highlighted the low efficiency of the turbine. Therefore, the study was carried out using computational fluid dynamics (CFD) to demonstrate the efficiency of the turbine as a function of the performance of different openings of the inlet nozzles, i.e., as 1-opening and individual pitot tube opening. In this work, a validation study was performed with the existing manuscript before further investigating the effects of the different openings of the inlet nozzles. The results show that the configuration of 4 inlets with 4 openings (4i4o) results in higher velocity and pressure distribution compared to 4 inlets with 1 opening (4i1o). Consequently, 4i4o obtained a higher torque value compared to 4i1o with a difference of 10%. Hence, the thrust and efficiency values for the 4i40 were 33.69% and 34.30%, respectively, higher compared to the 4i1o. The performance of the Tesla turbine with the specified optimal configuration increased very significantly compared to the previous research studies. It can be concluded that the introduction of the functional theory of the ‘pitot-tube’, which considers the gaps individually by having a separate inlet for each of them, had a great impact on the performance of Tesla turbine.

Advantages of the aerodynamic performance of micro‐Tesla turbines

AbstractTesla turbines, featuring bladeless turbomachinery and energy transformation using the viscosity of the working medium, have wide application prospects in renewable energy utilization as micropower equipment and portable power units and show better aerodynamic performance with a smaller turbine size. In this paper, a miniaturization method of Tesla turbines, including the stator and rotor, was proposed based on its sensitivity analysis results and flow similitude law. A typical Tesla turbine with a disc outer diameter of 100 mm was miniaturized to 50, 20, and 10 mm, respectively. In addition, the miniaturized Tesla turbines, including both the simplified single‐channel turbine model and the multichannel turbine model used in practical applications, were simulated numerically. The results show that the miniaturization method that maintains the two high‐impact dimensionless parameters at their optimal values is simple, reasonable, and effective. The isentropic efficiency of the single‐channel Tesla turbine decreases slightly with its scaling down. However, for the multichannel Tesla turbine in practical applications, the isentropic efficiency increases significantly with a decrease in turbine size, due to a decrease in the impact of the outermost disc channel on the flow fields of the inner disc channels (called the casing wall effect). This is embodied by the phenomenon that part of the working medium in the inner disc channels flows into the outermost disc channel through the nozzle‐rotor chamber, and the proportion of this part of the working medium decreases significantly with a decrease in turbine size. In conclusion, the Tesla turbine with a smaller turbine size exhibits better aerodynamic performance and has great potential in the field of microturbomachinery.

An Updated Design Procedure for Tesla Turbines

Tesla turbine rotor, a special case of the flow between two corotating disks, has been studied in the past analytically and the performance is discussed both qualitatively and quantitatively. However, there is no systematic design criteria/process given to design the rotor of a Tesla expander in the peer-reviewed literature. Such design procedure, presented in this article, allows researchers and engineers to design and optimise the rotor for a given fluid and design condition (Power, flow and rotational speed). In this article, we present a 0-D design methodology to calculate rotor design parameters such as disk diameters, the gap between disks, the number of disks and the rotational speed of the expander, and efficiency and power estimation. This design procedure is based on the correlations and optimal ranges present in the literature. The 0-D model discussed in this article is a promising design approach to the preliminary design of the Tesla rotor and then further fine-tuning could be done based on the CFD simulations when coupled with the stator. A case study is presented with a 3-kW air bladeless expander prototype in which the rotor is designed using the 0-D model approach and compared with 2D Computational Fluid Dynamics results.

FEATURES OF THE BOUNDARY LAYER ORGANIZATION IN TESLA DISC TURBINES

To ensure maximum efficiency of bladeless Tesla turbines, it is important to maintain a laminar flow regime within the boundary layer that forms on the disc surfaces. Depending on the flow regime, the state of the disc surfaces, and the geometry of the interdisk gaps, the nature of the boundary layer varies. It is crucial for the flow regime to remain laminar, and the distance between the discs should not exceed twice the thickness of the boundary layer. Experimental investigations of the characteristics of the boundary layer during the flow around turbine blades were proposed to determine the parameters necessary for achieving maximum efficiency. These experiments were conducted in an aerodynamic test rig that provided a uniform velocity field with minimal turbulence (0.7 %) within a speed range up to 0.33 Mach. The primary focus of these studies was to determine the location of the transition zone within the boundary layer, which allows for the examination of conditions for stable maintenance and characteristics of laminar flow. The transition zone was determined based on changes in the tangential friction stress in the experiments. The obtained results facilitated the establishment of the necessary dimensions for the inter-disk gaps and the optimum values of the similarity criterion Re from the perspective of flow regime. For a smooth surface, laminar flow within the boundary layer is maintained up to a relative coordinate of 0.17 x= from the start of the surface, across a wide range of Reynolds numbers. For a rough surface, the extent of the zone with a laminar boundary layer is approximately the same as that for a smooth surface at Re=3.6∙105. However, at Re=7.4∙105 the laminar flow terminates slightly earlier, at 0.13 x= , with a very short transitional zone between laminar and turbulent flow characteristics. The thickness of the laminar boundary layer on a smooth surface is 0.5…0.7 mm, while for a rough surface, it is slightly greater at 0.7…0.8 mm. Therefore, to ensure high efficiency of Tesla disc turbines, the distance between the discs should be maintained at 1…1.5 mm, considering the requirements for laminar flow.

Thermodynamic analysis of Tesla turbine in Organic Rankine Cycle under two-phase flow conditions

In the field of clean energy, Organic Rankine Cycle (ORC) is considered a vital method to utilize low-grade waste heat effectively. Due to certain application advantages in low power level ORC systems, the Tesla turbine is considered one of the essential choices for the core components of ORC systems. Given the inadequacy of the current research on the performance of the Tesla turbine under two-phase flow conditions, a one-dimensional model of the Tesla turbine was constructed in this paper to make it equally applicable to the two-phase flow conditions of wet working fluids. A model of the Tesla turbine and ORC system was constructed from the thermodynamic point of view, and five typical wet working fluids (R22, R417a, R134a, R152a, and R290) were selected to study the effects of the five wet working fluids on the thermal performance of Tesla turbine and ORC system. The effects of the changes in key structural parameters of the Tesla turbine on the performance of the Tesla turbine and the ORC system were further analyzed when different wet working fluids were used in the ORC system. The results showed that the highest turbine efficiency of 42.0 % was achieved when the Tesla turbine used R22 as the working fluid under the design conditions, while the highest turbine output power and the highest system thermal efficiency of 1.19 kW and 3.96 % were achieved when R417a was used as the working fluid. The analysis of the key structural parameters of the system showed that for the five different wet working fluids, the turbine efficiency, turbine output power, and system thermal efficiency increased monotonically with increasing rotor inlet radius. For each of the five wet working fluids, an optimum rotor speed, rotor outlet radius, and rotor gap distance exist, resulting in optimal turbine efficiency and system performance. The related work provides an important reference for the optimal design of Tesla turbines with wet working fluids.

CFD Simulation of Tesla Turbines Performance Driven by Flue Gas of Internal Combustion Engine

The reduced production of fossil energy, especially petroleum, has encouraged researchers to continuously increase the role of new and renewable energy as part of energy security and independence. A Tesla turbine is a device that can be used to recover wasted energy from exhaust gases, thereby increasing the overall energy use. The purpose of this study was to assess the performance of a Tesla turbine using various parameters such as engine speed, the gap between the disks, the diameter of the disks, and the number of disks. In this study, the performance of a Tesla turbine was simulated using computational fluid dynamics (CFD). The reference dimensions of this Tesla turbine are made with a slit diameter of 44 mm, a hole diameter of 10 mm, disc diameter of 140 mm, a disc width of 1.5 mm, a disc gap of 35 mm, a disc gap width of 4 mm, and a shaft length of 50 mm. The results of this study were in the form of torque and pressure drop values. In the variation of engine speed, the highest torque was at 1800 rpm with a torque value of 0.422 Nm, and the highest pressure drop was at 1800 rpm with a pressure drop value of 79161.5 Pa. In the disk gap variation, the highest torque is at a 7 mm disk gap with a torque value of 0.54 Nm and the highest pressure drop is at a 4 mm disk gap with a pressure drop value of 79161.5 Pa. In the variation of disk diameter, the highest torque was found on the disk with a diameter of 180 mm and a torque value of 0.831 Nm, and the highest pressure drop was on a disk with a diameter of 180 mm and a pressure drop value of 86753.5 Pa. In the variation of the number of disks, the highest torque was found at eight disks with a torque value of 0.765 Nm, and the highest pressure drop was found at eight disks with a pressure drop value of 82031.3 Pa. After performing this simulation, it can be concluded that at variations in engine speed, the higher the engine speed, the higher the value obtained and the variations in the disk gap, disk diameter, and number of disks. There are several values of torque that increase and decrease because the input value given cannot always increase the torque value in these variations.