Peak Cp Research Articles

Experimental and artificial neural network (ANN) study on the impact of three different metal oxide nanoparticle combustion enhancers enriched on mahua biodiesel-diesel fuelled CI engine

Abstract The prediction of CI engine parameters has acquired significant attention and is regarded as a crucial tool for engine research and diagnosis studies. This contribution compares two different approaches for diesel engine viz. experimental and artificial neural networks (ANNs) predictions of performance and emission outputs. The base fuel M30 blend consist of mahua biodiesel 30 (% v) and 70 (% v) of diesel. The M30 blend and 50 ppm concentration of NPs (CeO2, CuO, and TiO2) were chosen for basic experimentation. The findings indicate an increase in BTE by 9.1%, peak CP by 11.3%, and HRR by 10.2%, with a decrease in BSFC by 13.7%, CO by 30.4%, HC by 30.1%, smoke by 34.7%, and NOx by 7.1%, resulting from the addition of 50 ppm CeO2 NP to D70M30 blend. The widely used backpropagation technique for ANN is implemented in multilayered feedforward design. To forecast the engine characteristics of a CI engine, a network structures including two inputs and one output is used. The given ANN model examined D100, M30, M30CeNP50, M30CuNP50, and M30TNP50 blends, using engine load and biodiesel with nanoparticle blend as the two input factors. A data-driven ANN model was created to forecast the optimised engine characteristics. The lowest and highest value of correlation coefficient (R2) and mean square errors (MSE), mean relative error (MRE) were found to for peak CP, HRR, BTE, BSFC, CO, CO2, HC, NOx and smoke. Using ANN one can choose right blend ratio among the variety of fuels blends for an appropriate requirement without much experimentation.

Numerical and experimental investigation of Darrieus vertical axis wind turbines to enhance self-starting at low wind speeds

Wind energy, being renewable, cost-effective, and environmentally friendly, has attracted global attention. However, due to suboptimal performance and limited research, vertical axis wind turbines (VAWTs) lag behind horizontal axis wind turbines (HAWTs) in commercial applications, particularly for large-scale installations. This study aims to improve the self-starting capability of the Darrieus VAWT. While some parameters, such as the number of blades (N) and solidity (σ), have been studied extensively, the airfoil shape has not received as much attention. This study compares the performance of National Advisory Committee for Aeronautics (NACA) airfoils and Selig airfoils at a Reynolds number (Re) of 40,673. The investigation revealed that the NACA0015 airfoil exhibited the highest peak power coefficient (Cp). Further analysis utilizing an advanced double multiple stream tube (DMST) code in MATLAB increased the peak Cp by adjusting the thickness-to-camber ratio (t/c) of the NACA0015 airfoil, resulting in a 12.50 % increase in the maximum achievable Cpat a Re of 40,673. This study compared four modes of VAWT operation, utilizing the NACA0015 airfoil and a modified NACA0015 airfoil for both straight-bladed and embossed-bladed VAWTs. The results showed that the modified NACA0015 airfoil for embossed-bladed VAWTs exhibited the best self-starting capability and rotation at wind velocities of 1 to 9 m s-1. Additionally, the self-starting force required by embossed-bladed VAWTs was lower than that needed by straight-bladed VAWTs due to the ability of the embossed material to enhance airflow attachment to the VAWT and suppress turbulence.

Numerical Investigation of Vertical-Axis Hydrokinetic Turbine on Side-by-Side Configuration

Abstract Indonesia, a maritime country, has a renewable energy source that has not been utilized to date, which is ocean current energy, with a potential reaching 17.9 GW. Ocean current energy conversion can be harnessed by using a turbine. A turbine farm is one of the solutions that can be applied to harvest energy and utilize the full potential of the energy available. The arrangements of the turbine on a turbine farm become crucial because the wake generated may affect the performance of the turbines. In this study, numerical simulation will be carried out to find the best y/D distance for twin turbine in low-velocity ocean currents. The simulation is carried out using Computational Fluid Dynamics software with different variations of lateral spacing (y/D 1.2, 1.5, and 2.0). The performance of each turbine, such as torque and Cp, is obtained and compared to a single turbine arrangement. At y/D 1.5 peak Cp achieved at 0.45, a 53% increase from single turbine arrangement. Using a twin turbine arrangement may be beneficial in developing ocean current turbine farms in the future.

Increased coproporphyrin serum levels in healthy volunteers treated with the cholesterol uptake inhibitor ezetimibe.

Ezetimibe undergoes glucuronidation that results in the active metabolite ezetimibe phenoxy-glucuronide (ezetimibe-glucuronide). This phase-II metabolite was shown to interact with the clinically relevant hepatic transporter organic anion transporting polypeptide (OATP) 1B1. In recent years, coproporphyrin I (CPI) was established as a Tier 1 biomarker for OATP1B-mediated interactions among other endogenous substrates like CPIII. To evaluate whether levels of the biomarker are affected by ezetimibe treatment, we assessed the impact of ezetimibe and ezetimibe-glucuronide on OATP1B1-mediated transport of CPs invitro. Then, we quantified CP levels in serum samples of healthy volunteers treated with a single oral dose of ezetimibe (20 mg) alone or in combination with rifampin (600 mg). Results from our invitro experiments showed a significant reduction in cellular CPI accumulation in the presence of ezetimibe-glucuronide with an IC50 of 1.97 μM [95% CI: 1.04 to 3.96], while CPIII accumulation was impacted by 10 μM and above. In the invivo study, we observed peak CP concentrations 1.33 h after dosing, which is closest to the tmax of the ezetimibe metabolite. Co-administration of ezetimibe with rifampin resulted in even higher serum CP levels. The AUC0-24h of CPI and CPIII increased two- and threefold, respectively, after concomitant dosing compared to ezetimibe alone. Moreover, we quantified CP levels in cumulative urine from both study phases where the renally excreted amount (Ae) of CPI and CPIII increased after ezetimibe and rifampin co-administration compared to ezetimibe alone. In conclusion, our findings indicate that rifampin co-administration results in additional inhibition of OATP1B1 invivo.

Scaling effects on peak wind load estimation for low-rise buildings: An experimental and analytical study

Though scaling effects on estimation of peak wind loads are extensively documented in the literature, there is a lack of systematic comparison of such scaling effects across different model scales tested in wind tunnels. Moreover, the limited studies on large-scale physical models accepted the inadequacy of simulating the large turbulent eddies rather than addressing the missing low-frequency turbulence simulation inherent in such large-scale testing. This study provides an in-depth comparison of estimates of peak wind loads obtained using a range of experimental scaled models (1:100 and 1:6 model scales) of the Wind Engineering Research Field Laboratory (WERFL) building while applying a Partial Turbulence Simulation (PTS) methodology to incorporate the effects of turbulence. Large-scale wind tunnel testing of structures provides the advantage of achieving an improved Reynolds number (Re) similarity, more accurate geometric similarity, and enhanced resolution of flow details such as corner vortices, than is possible with the use of smaller model scales. However, as the model scale increases, achieving turbulence similarity becomes challenging due to limitations in simulating the low-frequency turbulent eddies in the wind tunnel. The PTS method has been used in the recent past to account for the low-frequency turbulence effects in the peak wind load estimation. The method is referred to as 1DPTS when considering longitudinal turbulence components only and 2DPTS when considering both longitudinal and lateral turbulence components in the analysis. The computationally intensive 2DPTS can be further simplified by using a weighted average method as described in this paper as “weighted average PTS.” The current study explores the effect of scaling on peak wind load estimation by using the 1DPTS, 2DPTS, and weighted average PTS methods. Results from the multi-scale experimental tests demonstrate that using larger model scales and compensating for the low-frequency turbulence deficit in the post-test analysis significantly improve the agreement with the prototype data owing to the simulation of a higher Reynolds number. Furthermore, comparing the results of the proposed weighted average method with full-scale data reveals its potential as a substitute for the original 2DPTS method, offering enhanced accuracy, particularly at the roof corner for oblique wind directions. While the effects of Re are well known, the findings of this study explore its impact in conjunction with the application of the PTS methods on peak Cp estimation across five different model scales with Re ranging from 3.65 × 104 to 2.43 × 106, the latter being closest to the full-scale (field) Re. The findings provide new insights into how large-scale physical model testing in high Re flows, supported by analytical PTS-based compensation, can enhance the accuracy of peak wind load estimations for critical scenarios including cornering winds that generate conical vortices.

Wind tunnel tests of a two-bladed Savonius wind rotor with novel parabolic blades

The study presents an experimental research on a vertical-axis Savonius wind rotor featuring optimized parabolic blades. This parabolic blade is developed by optimizing its sectional cut-angle through a series of numerical simulation. The parabolic-bladed Savonius rotor of various aspect ratios is tested in a low-speed wind tunnel to evaluate its power coefficient ( CP) along with its self-starting capability. For a direct comparison, the tests are also conducted for a rotor with the semicircular blades. The wind tunnel tests demonstrate the peak CP of the parabolic and conventional semicircular bladed rotors to be 0.165 and 0.138, respectively at a tip-speed ratio of 0.67 and an aspect ratio of 0.9. The wind rotor with the parabolic blades shows an improvement of CP by 19.56% against its conventional semicircular counterpart. With the inclusion of blockage correction, the test rotors with parabolic and semicircular blades show the CP of 0.161 and 0.134, respectively.

Dependence of drag coefficient on the spectral width of ocean waves

The sea-surface roughness or drag coefficient is ascribed to the effect of various components of ocean waves. Many studies have been focused on the investigation of the dependence of drag coefficient on sea states that are usually denoted by wave age. However, no universally accepted relationship has been obtained up to now and the results are significantly scattered or even contradicted. We reviewed the parameterizations of sea-surface roughness as a function of wave age, and found that the phase speed at spectral peak cp is an important parameter to characterize the drag coefficient. For the same wave age, drag coefficient increases with increasing cp. Contrary to the traditional concept, the older waves with greater cp possesses higher sea-surface roughness for the same wind speed because more wave components participate the air–sea interaction and intensify the wind stress. With the buoy meansurements and the theory of equilibrium range of wind waves, we estimated fricition velocity and proposed that the frequency bandwidth and spectral width of the wave spectrum are more suitable parameters than the traditional wind speed and wave age to be used to parameterize drag coefficient. This study provides a new way to estimate wind stress through the reliable spectra of ocean waves.

Parameters Cp and Ct in Snyder Synthetic Unit Hydrograph Due to Land Use Changes in Napel Sub-watershed, Bengawan Watershed

The parameters Cp and Ct depend on the characteristics and slope of the watershed. Watershed characteristics include types of land use that are always dynamic over time. The slope of the watershed affects the smoothness and velocity of runoff flow. The development of an area will cause changes in land use which tend to become more impermeable, of course also affecting the smoothness and speed of runoff flow. This of course results in changes in Cp and Ct in a watershed. Changes in land use in the Napel watershed within 7 years starting from 2015 to 2021 have decreased in areas of jungle forest and other water catchment areas. This research was conducted to determine the influence of land use change on peak discharge and Cp and Ct parameters. The method used is the Snyder Synthetic Unit Hydrograph, which has been tested for suitability against the Measured Unit Hydrograph with validation results included in the very strong correlation category. The Ct value used in 2015 was 1.65 and in 2021 it was 0.78 while the Cp value used in 2015 was 1.4 and in 2021 it was 1.1. The results of the analysis using the Snyder method produced a discharge of 417.882 m3/s in 2015 and 619.52 m3/s in 2021. The resulting discharge shows a significant increase.

Avaliação da Influência dos Parâmetros de Processamento na Manufatura Aditiva do Aço VP50IM por PCGTAW

Abstract The wire arc additive manufacturing process or WAAM (Wire Additive Arc Welding) is recognized as a process able of making pieces of high geometric complexity, with mechanical properties comparable to those of the cast material. However, there are significant challenges associated with WAAM, such as undesirable microstructures and mechanical properties, high residual stresses and geometric distortion. This study aims to contribute to the selection of deposition parameters for VP50IM steel using WAAM via pulsed TIG (Tungsten Inert Gas) and characterization of the generated stacking, using the Central Composite Complete methodology, CCC. In this study, the peak (Cp) and base (Cb) current, wire feed speed during peak (Vap), base (Vab) and welding speed (Vs) were varied. The ideal parameter presented was Cp=200A, Cb=100A, Vap=2.9cm/min, Vab=1.2cm/min and Vs=20cm/min. Tensile tests showed up to 15% greater resistance in the samples in the longitudinal section in the welding direction compared to the transverse direction. Hardness tests demonstrated up to 9% less hardness at the center of the stack compared to the top and bottom. The fracture analysis of the specimens showed ductile fracture.

Performance Improvement of a Savonius Wind Turbine using Wavy Concave Blades

As the best replacement for fossil fuels, green energy resources have established their significance on a worldwide basis. The availability of wind energy makes it the best promising form of green energy. For transforming wind kinetic energy into mechanical energy at low wind speeds, the Savonius wind rotor is regarded as the best choice. The main goal of the current study is to improve the power coefficient (Cp) and torque coefficient (Ct) of the Conventional Savonius wind turbine (SWT) by modifying the inner surface of the blade using a wavy profile. The aerodynamic performance of the wavy turbine is then compared with the conventional turbine in terms of Cp and Ct. The study is conducted using numerical simulation with the assistance of the ANSYS software. The flow characteristics around the turbines are solved utilizing the SST k-ω turbulence model. The simulation outcomes confirmed that the Cp of the wavy rotor increased by about 14.5% at a tip speed ratio of λ= 0.4. Additionally, outcomes showed the peak Cp is 0.18 at λ=0.7 which is 12.5% greater than the conventional SWT

Assessment of fairing geometry effects on H-Darrieus hydro turbine performance using 2D URANS CFD simulations

This study aims to enhance the hydrodynamic efficiency of the fairing system and increase the power coefficient Cp of a three-bladed H-Darrieus turbine by investigating various geometries and configurations in comparison to the reference model. 2D CFD modeling and URANS calculations along with the k-ω SST turbulence model are employed for conducting parametric studies. The analysis focuses on assessing the geometric parameters of the fairing system that affect its behavior, such as the angle of incidence α and the chord length C of the fairing profile. It was found that at x/C=0.39934, the normalized power coefficient Cp/Cp,max of H-Darrieus equipped with the fairing amounts to 0.967581, whereas at x/C=0.750825, it attains Cp=0.486284. A power coefficient of Cp=0.621315 is achieved when an angle of attack α=10∘ and a tip speed ratio λ=2 are combined. In addition, the optimal operating point Cp for both fairing profiles is λ=2. In addition, maximum performance is reached at α=18∘ for the Eppler-420 profile, with a peak Cp=0.662, whereas the S1223-RTL profile demonstrates optimal performance at α=30∘ , with a peak Cp=0.728. Differences in the maximum and minimum ΔP∗ values between the Eppler-420 and S1223-RTL are also noted. It is observed that the S1223-RTL profile displays lower drag Cd and lift Cl coefficient values than the Eppler-420 profile up to α≈22∘. finally yet importantly, the highest Cp is observed at a chord length of C=4.0R, while the lowest occurs at a chord length of C=2.5R. Both Cd and Cl exhibit relative constancy for chord lengths shorter than C=4.0R.

Extracellular volume is an independent predictor of peak cardiac power in asymptomatic patients with moderate-to-severe aortic stenosis

Abstract Funding Acknowledgements Type of funding sources: Other. Main funding source(s): The PRIMID study was funded by an NIHR fellowship (Post-Doctoral Fellowship supported by the National Institute for Health Research (NIHR-PDF 2011–04–51 Gerald P McCann.) Background Cardiac power (CP) describes the cardiac work done to maintain arterial pressure in the vasculature and peak CP is the ceiling of pumping performance the heart can achieve. Mean pressure gradient adjusted CP (MPG-CP) gives a more accurate representation of afterload in patients with aortic stenosis (AS) but its association with left-ventricular remodelling parameters is unknown. Purpose To establish the determinants of peak MPG-CP in asymptomatic patients with AS. Methods In this prospective, multi-centre observational study, asymptomatic patients with moderate to severe AS underwent echocardiography, cardiovascular magnetic resonance (CMR) imaging and cardiopulmonary exercise testing. Peak MPG-CP was calculated at peak exercise during an incremental symptom-limited exercise test on semi-supine ergometer, using the formula shown (Figure-1). Clinical and imaging univariable and multivariable associations of peak MPG-CP were assessed by linear regression. Results Peak MPG-CP was measured in 86 patients (mean age 66±12 years, 77% male, mean aortic valve area (AVA) 1.08±0.33 cm^2). On univariable analysis, peak MPG-CP was directly correlated with echocardiogram-measured AVA, peak pressure gradient, max velocity, and CMR-measured myocardial perfusion reserve (MPR), LV mass index (LVMI) and LV end-diastolic volume index (LVEDVI), and inversely correlated with extracellular volume (ECV) and NT-proBNP (Table-1). ECV was the only variable independently associated with peak MPG-CP regardless of which measure of AS severity was inputted in the multivariable model. Conclusions ECV, a marker of diffuse interstitial fibrosis, is an independent predictor of peak MPG-CP in asymptomatic patients with moderate-severe AS. Given ECV's role as a prognosticator, CP parameters may be important markers of subclinical disease and serve as surrogates for fibrotic burden and risk-stratification tools in asymptomatic AS.

Experimental and numerical aerodynamic analysis of an elevated beachfront house

Elevating coastal houses enables residential communities to reduce the risk of flooding due to tropical cyclones. However, wind-induced damage during such events requires an understanding of the inherent wind forces to improve damage mitigation techniques and assessment of climate-related risk in insurance models. In this study, wind-tunnel experiments and computational fluid dynamics (CFD) simulations are conducted for a typical elevated 1:25 scale beachfront house, possessing a 5:12 pitched gable roof with overhanging eave. An atmospheric boundary layer (ABL) wind field is generated in a low-speed wind-tunnel to replicate conditions experienced during tropical cyclones. Testing is performed for a range of incident wind angles to understand the full aerodynamic consequences of strong winds. Measured pressure coefficient (Cp) distributions are compared with CFD simulations using steady-state and transient Delayed Detached-Eddy Simulation (DDES) within ANSYS Fluent 2021 R1. Net Cp values surrounding the overhanging eave are considered to evaluate the role of this typical geometrical feature. It was found that larger uplift suction occurred at incident wind angles of 45°and above, after which the suction remained stable. The roof panels are subjected to the greatest upward suction, where critical regions occur at the roof ridge. The size of the low-pressure regions is determined by the incident wind angle and ensuing flow separation wherein DDES is found to reproduce additional aerodynamic features arising from unsteady turbulent flow. DDES offers improved predictive capability when mean pressure forces are considered but falls short as an accurate means to efficiently evaluate peak Cp distributions.

Validation metrics and turbulence frequency limits for LES-based wind load evaluation for low-rise buildings

The accuracy of Large-Eddy-Simulation (LES) in modeling wind loads, especially components and cladding loads, does not currently fulfill its potential. The lack of extensive consideration for wind loading requirements and their direct influence on LES duration and mesh size are identified as research gaps. This study presents a validation metric for LES modeling of low-rise buildings, including the wind field and aerodynamics. Most of the proposed validation requirements are adapted from Boundary Layer Wind Tunnel (BLWT) testing requirements to highlight the challenges and opportunities for LES. The turbulence spectral frequency limits significantly contribute to the cost-accuracy trade-off in LES. A stationarity test of recorded time histories is proposed to determine the optimal duration, i.e., low-frequency limit, for statistical parameters other than the peak. An analytical expression is proposed for the LES mesh size estimation from the target maximum frequency limit and corresponding spectral energies. The proposed validation metric is demonstrated with LES models of a low-rise building targeting respective BLWT tests in three wind directions and in three exposures. Despite some limitations, the peak Cp error was within ±10% of the BLWT value range. The optimal normalized durations from LES were one order of magnitude shorter than those from the BLWT cases. The peak values did not show a significant difference in trend from BLWT; hence the duration dependence of peak uncertainties remains relevant for LES. The BLWT data supports the previously proposed high-frequency limit of two. LES models can produce reasonably acceptable wind loads with proper attention to the existing and new requirements, as shown in the present study.

Archimedes Spiral Wind Turbine performance study using different aerofoiled blade profiles: Experimental and numerical analyses

Wind power is one of the most quickly expanding forms of clean energy. A novel horizontal axis wind turbine type, the Archimedes Spiral Wind Turbine (ASWT), is built for residential applications. The influence of the rotor pitch to diameter ratio (2s/D) and the aerofoil blade profile on the productivity of ASWT is investigated using experimentation and computer simulation. To fulfill the validation of the experimental work, the ANSYS Fluent solver provides the numerical solution. The tests are performed on a modified ASWT with a nominal blade thickness and blade angles of α1 = 25°, α2 = 50°, and α3 = 60° for the first, middle, and third blades. Wind speeds of 8 and 10 m/s were used. The NACA4401 ASWT with (2s/D) = 0.30 is the best-studied design. At a wind speed of 10 m/s, the maximum CP of the conventional, modified, and aerofoiled ASWTs is 0.243, 0.286, and 0.3045, respectively, at tip speed ratios (λ) of 1.5, 2, and 2. Compared to the conventional and modified ASWT, the aerofoiled ASWT exhibits a 26.88% and 6.47% improvement in the peak CP.

An empirical and CFD analysis of combustion performance of a diesel engine fueled with tomato seed oil biodiesel

Abstract Tomato seed oil biodiesel (TSOB) could be considered as a second generation and clean-burning renewable substitute for petroleum diesel. It is about 72% by weight of tomato waste, which contains an average of 24% oil. This paper investigated the effects of four different Diesel-TSOB blends on the combustion performance of an indirect injection (IDI) diesel engine. In-cylinder pressure (CP) and combustion parameters at five different engine loads and seven speeds were experimentally measured. Then for 2D CFD simulation of the emissions and combustion processes, AVL FIRE software was used and the results evaluated with experimental data. The purpose of the study was to determine the combustion process and its effects on the performance and emissions of the engine. The outcomes for B10 at 100% load addressed that, the peak CP of about 67 MPa was found at 1200 rpm which occurred at 13° ATDC, while at 2200 rpm the peak CP was 69 MPa and occurred at 1° ATDC, and at 2400 rpm the peak CP was found to be about 66 MPa which occurred approximately at TDC. The simulated results found that the peak in-cylinder temperature of 1600° K corresponds to the 10% TSOB blend (B10) and the longest mixing-controlled period occurs for B10 at 27° CA. The simulation also showed that B5 had the longest jet penetration of about 44 mm (at about 100° CA) in comparison to 43 mm for B20, 41 mm for B10 and 39.8 mm for B0 (pure diesel) which occurred at less than 100° CA. The longest jet penetration duration of was found to be about 44 mm for B5 at about100° CA. The results showed that B10 has the biggest accumulative heat release (approximately 1900 J) and highest fuel energy efficiency. The 2-D CFD simulation revealed that the unburnt equivalence ratio in the main combustion chamber is lesser than in the spherical combustion chamber.

Study of wind loads on asphalt shingles using full-scale experimentation

Asphalt shingles constitute more than 80% of the roofing materials in current residential housing in the United States. Many post-disaster surveys have reported the failure of these roofing elements below the design level wind event. Research to realistically model the aerodynamics of asphalt shingles at full-scale is limited, resulting in knowledge gaps in peak wind loads and effects of permeability. In this study, the aerodynamics and wind resistance of asphalt shingles are studied by using a monoslope roof tested at Florida International University's Wall of Wind Experimental Facility. Results from both aerodynamic and failure assessment test protocols showed that shingles near the upper corners of the roof were subjected to high suctions due to cornering winds. This presents a critical loading case for which asphalt shingle roofing systems are not typically tested using current standard tests. Moreover, the extent of permeability underneath the shingles was observed to vary with the spatial location of shingles and wind direction. Finally, the comparison of area-averaged peak Cp values obtained from this study with GCp plots in ASCE 7-16 Standard showed that these provisions, which do not consider the effects of permeable roofing elements (e.g., shingles), can underestimate wind loads on asphalt shingles.

Water consumption peak demand factor: Effectiveness analysis with different approaches

The design of the water distribution networks in a given region must guarantee 24-hour supply, meeting the times of greatest demand, defined as factors of peak consumption. Thus, it is important that water reaches users effectively, ensuring adequate quantity and quality for carrying out daily activities. The premise then is the average flow demanded by the population, and the fluctuations that may occur from this value, weighted from the dimensionless peak coefficients K1 (coefficient of the day of greatest consumption) and K2 (coefficient of the hour of greatest consumption). In this paper, these coefficients are calculated from both water consumption data and from the application of empirical equations. These values were compared with those suggested by the NBR 12218/2017 standard, which suggests K1 = 1.2 and K2 = 1.5 in the absence of water consumption data. However, some surveys that assessed water consumption in three regions based on water consumption data for three to four years indicated that the peak coefficients recommended by the standard may lead to undersizing of the supply network. In one of the cases assessed, the values of K1 and K2 respectively corresponded to 2.19 and 4.95. Results of two studies previously developed at the Faculty of Civil Engineering, Architecture and Urbanism of the State University of Campinas (FEC-UNICAMP) were used for the calculation based on water consumption data. These studies defined the peak water consumption coefficients for the same three regions examined by the present research: Parque Jambeiro and Parque Oziel, located in the city of Campinas (third most populous city in the State of São Paulo, with an estimated 1,204,703 inhabitants in 2019), and Jardim América II, located in the municipality of Várzea Paulista, in the interior of the State of São Paulo, based on data provided by the water provider. The analyses carried out considered that the peak water consumption factor Cp is given by the product of K1 and K2. Seven empirical equations, available in the specific literature and developed in different locations, were used. As the empirical equations were developed in different regions, the average of the results obtained through these equations was used in order to reduce the existing uncertainties, related, for example, to the socioeconomic profile and climate, parameters that vary according to the region of study. As a result, this research shows that in all the neighborhoods observed, the normative suggestion for the Cp value was below those obtained by applying the empirical equations in all the years used to calculate the coefficient. So, there was no year in which the normative reference was sufficiently adequate to describe water consumption. Furthermore, the evaluation using water consumption data resulted in a peak coefficient equivalent to 240% of the normative suggestion (2.4 times higher) whereas the empirical equations suggest the adoption of a value corresponding to 200% of the indicated value by the standard (twice as high). It was also found that the computation of Cp through empirical equations resulted in values 1.55 times higher than those obtained from the water consumption data. As the calculation of the design flow depends directly on the peak consumption coefficient, the use of smaller values leads to lower design flow and, consequently, to undersized network diameters. As a direct consequence, there are greater head losses at times of higher flow. This situation should result in a lack of water in peak consumption days and times, so as not to serve the population continuously, which is a premise of the public supply system. Future research may focus on expanding the number of regions evaluated in the comparison between different ways to calculate the peak water consumption coefficients, and it is also possible to explore the evaluation of water consumption data to determine the Cp value and the subsequent correlation with local factors such as resident population, supplied area, typical climate, among other factors, adding value to the results already existing in the specific literature, and also expanding the knowledge related to the dimensioning of water distribution networks.

Optimization of radial inflow wind turbines for urban wind energy harvesting

Radial (inflow) turbines with volutes have received limited attention in the body of literature for open-field wind harvesting. Few existing data in the literature indicate low maximum Cp, around 0.1. This study pursues demonstration of competitive radial wind turbines (RWT) towards exploring their potentials and increase the alternatives for a future urban energy planner. RWT may have advantages in adapting the renewable energy concept into buildings due to their an order-of-magnitude lower rotational speeds compared to propeller turbines, enclosed rotors and discharge of air uniquely from the top of the turbine (therefore the building). Moreover, such features may enable low-noise and fatigue-free rotors made of less durable but recyclable materials, crucial for acoustical comfort, safety and sustainability in urban areas. Design exploration over the complex 3D flowfield of the turbine is pursued by machine learning algorithms coupled with Computational Fluid Dynamics simulations. With the achieved peak Cp of 0.29 at Rec = 1.7 × 105, 103% improvement is attained relative to the existing RWTs with identical simulation methodologies. A sensitivity analysis revealed the most important parameters. The optimized turbine is compared with traditional alternatives, and it was elucidated that RWT is a competitive alternative among conventional alternatives with the described additional fundamental advantages.

Peak lift-to-drag ratio enhancement of the DU12W262 airfoil by passive flow control and its impact on horizontal and vertical axis wind turbines

Recent studies have revealed that passive leading-edge slots on the pressure side has the potential to increase both the peak and overall CL/CD of airfoils and may possess an advantage over active methods. This work pursues application of such novel slots to the modern DU12W262 airfoil with a flexible slot-shape parametrization coupled with an optimizer to allow other slot concepts as well (suction side and trailing edge slots). Experimentally validated Computational Fluid Dynamics (CFD) simulations are employed for this purpose. It is shown that 16% peak CL/CD improvement and overall α-CL/CD rise are observed without any penalty in stall range. Implications of these are demonstrated on Horizontal- and Vertical-Axis Wind Turbines (HAWT and VAWT) by CFD. It is shown that, HAWT peak Cp of increases by 3.2%. Alternative BEM simulations predict this as high as 7.5%. For the VAWT, the peak Cp remains unchanged, however high tip-speed-ratio (λ > 3, low wind speed) Cp increases between 3.5 and 9.6% throughout the operational range. This may directly reflect into VAWT urban operation. In summary, the concept is highly successful in improving peak and overall CL/CD of a modern airfoil, and this yields to significant enhancements in both HAWTs and VAWTs.