Total Pressure Values Research Articles

Pressure Change in a Duct with a Flow of a Homogeneous Gaseous Substance in the Presence of a Point Mass and Momentum Sink of Gas

The flow characteristics of homogeneous gases in complex systems are an important issue in many areas, including underground mines. The flow in mine excavations and ventilation systems is described by known mathematical relationships that could be applied to various cases. In this paper, a flow in a duct with a local sink of mass and momentum for multiple variants of cooperation of a mechanical fan was analyzed. The relationships for the total and static pressure of air in the duct were derived. In the next stage, a calculation example of how the mass flow rate of air, and the total and static pressure of the flowing air will change in the tested sections for the duct with and without a sink, is presented. The derived formulas and calculated values for the considered calculation case allow the verification of the obtained relationships at the measurement station. Analyzing the results of the examples presented in the article, it can be concluded that the total and static pressure at the sink point differ depending on the equation of motion used. In the case of the classic equation, the value of total pressure is lower than the value calculated from the new equation of motion, and the difference between them is about 20 Pa. In the case of static pressure, this difference is about 46 Pa. Qualitative differences in the static pressure distribution at the release location were also demonstrated. Depending on the applied approach, positive or negative changes in the static pressure are noticed. The presented form of the equation of motion made it possible to determine the flow characteristics in the duct with a point mass and momentum sink in the case of the operation with and without a fan.

Resolving nonuniform flow in gas turbines: challenges, progress, and moving forward

Abstract The flow in gas turbines exhibits a highly unsteady, complex and nonuniform manner, which presents two main challenges. Firstly, it introduces instrumentation errors, contributing to uncertainties when calculating one-dimensional performance metrics during rig or engine tests using fixed-location rakes. Secondly, it raises mechanical concerns, including high-cycle fatigue due to blade row interactions in turbomachines and thermal fatigue caused by hot-streaks at the combustor exit. Experimental characterisation of the flow nonuniformity in gas turbines is highly challenging due to the confined space and harsh environment for instrumentation. This paper presents recent efforts to address this issue by resolving the nonuniform flow in gas turbines using spatially under-sampled measurements. The proposed approach utilises discrete probe data and leverages a ‘Fourier-based approximation’ method developed by the author. The technique has undergone preliminary experimental validation involving reconstruction of the total pressure distribution in a multi-stage axial compressor and the total temperature field at the exit of the combustor and high-pressure turbine. Results show that, in the multi-stage axial compressor environment, reconstruction of inter-stage total pressure is achieved using a reduced dataset covering less than 20% of the annulus with reasonably good accuracy. The reconstructed total pressure yields almost identical mean total pressure values at all spanwise locations, with a maximum deviation of less than 0.02%. Additionally, reconstruction of the total temperature distribution at an engine-representative full annulus combustor is achieved using measurements at ten carefully selected circumferential locations. Results show that the reconstructed temperature field successfully captures the primary features associated with combustor exit temperature flow. The reconstructed temperature field yields excellent agreement in the magnitude of radial temperature distribution factor (RTDF) and overall temperature distribution factor (OTDF) predictions to the experiment, with a deviation of less than 0.5% for RTDF and less than 2.5% for OTDF. Lastly, reconstruction of the total temperature distribution at the exit of the GE E3 high-pressure turbine (HPT) is achieved using measurements at eight carefully selected circumferential locations. Results demonstrate remarkable robustness in resolving the temperature profile at the HPT exit with high fidelity, irrespective of the HPT inlet conditions. The initial validation results are promising, demonstrating that the new probe layout scheme and the Fourier-based approximation method enable effective characterisation of flow nonuniformity in gas turbines, thereby providing valuable insights into the complex flow of gas turbine engines.

Design, assembly and testing of an upgraded aeroacoustics wind tunnel facility

The Aeroacoustics Laboratory in the Department of Aerospace Engineering at Penn State currently serves several areas of experimental research. Most notable in the laboratory is the Anechoic Chamber of which the Aeroacoustics Wind Tunnel is an integral part. In recent years the dominant areas of research have included model aircraft exhaust jets and model rotors for helicopter applications involving detailed noise experiments. In the jet noise area, the applications have included aircraft in both flyover and take-off configurations. In the flyover application the air flow surrounding the exhaust jet has a significant effect on the radiated noise and must be simulated to produce experimental results that will be most useful in preliminary design of noise suppression applications. The Aeroacoustics Wind Tunnel at Penn State serves the purpose for this simulation. During aircraft take-off, the aircraft airspeed is in a range exceeding 250 ft per second, or Mach number of over M = 0.22. In the years preceding 2022, the velocity of the free jet flow of the Penn State facility was limited to less than 200 ft/sec. This paper reports on a project to design upgrades to the existing wind tunnel to improve the test section flow velocity to values closer to the 250 ft/sec target. The approach began with a preliminary design of the return flow ducting to convert the open jet, open return wind tunnel to a closed return tunnel. The concept is to make use of the flow energy in the exhaust of the tunnel to boost the input energy to the inlet fan that drives the flow to the test section. An integral part of the preliminary design involved making use of an upgraded flow analysis computer code to predict the gain in test section velocity of the new facility. For the available horsepower of two fans in the facility, the configurations of the existing and upgraded wind tunnel were entered into this analysis code based on a quasi-one-dimensional formulation. The code included empirical data formulated to include the various shapes of the components of the tunnels. The relative flow velocities in each section used simple incompressible continuity to calculate all velocities in the component sections. The average dynamic pressure in each section is calculated from the flow (constant) density and the velocity squared. Each section had a non-dimensional pressure loss parameter calculated from empirical data (from the relevant literature). The basic code (using the Excel algorithms) was based on a predictor-corrector concept in which the calculation was initialized with the estimated velocity and pressure of the flow at the entrance to the test section. The loss in each following section is estimated to determine the loss in the total pressure and the cumulated loss compared to the gains made at the two fans in the circuit. The initial guess is adjusted based on the total pressure value at the end of the circuit. During the related experiments, measurements of the total and dynamic pressure were performed at several joints between sections and compared to the values predicted in the analysis code. Various settings of the horsepower of the drive fans were used and the results were compared to flow measurements for the tunnel configurations (predominantly for the open return and closed return tunnel setups available before and after the upgrade project.) Results of the analysis and experiments are presented and analyzed together with the remaining activities planned for the coming months.

Intake Characteristics and Inhomogeneity of Supersonic Passage

The type, quantity, location, geometry and size of the intake passage will directly affect the quality of the engine, and then affect the whole propulsion system and even the performance of the aircraft. In this paper, the intake characteristics and inhomogeneity of three different passage structures are studied under supersonic conditions. The numerical simulation models of the intake passages of F-16, F-18 and J-10 were established, and the steady-state calculations were carried out under the condition of Mach number 1.2. In the three intake passages, the total pressure decreases gradually along the flow direction, and the pressure loss near the wall is large, while the total pressure value far from the wall is large, and the pressure field is relatively uniform. The F-18 intake passage has relatively small inlet pressure and total inlet and outlet pressure loss. In terms of inlet uniformity, the intake passage of F-16 has the highest value, F-18 has lower value, and J-10 has the lowest level of inhomogeneity.

SolidWorks Flow Simulation: Selecting the optimal mesh for conducting CFD analysis on a centrifugal fan

The accuracy of mesh use determines the suitability of simulation results with experimental test results, therefore it is necessary to study the type and number of mesh used for flow simulation. This study aims to investigate the type of mesh and the number of cells that are appropriately used in the simulation of centrifugal fans using the Solidworks Flow Simulation module. The research was conducted by comparing the simulation results with the experimental results on centrifugal fans that have been carried out by previous studies. In this research, the type of mesh used is global mesh. The parameter of determining the number of cells is done by varying the mesh level because the mesh level affects the number of cells. In this simulation study, the boundary condition is set to one flow volume of 5 m3/h and a rotation speed of 92.362 rad/s. In this study, the total pressure and efficiency of the centrifugal fan are the things that are seen from the comparison of flow simulation with the experiment. Based on the simulation results that have been carried out, mesh levels 1 to 4 show results that differ significantly from the experimental results. At machine levels 5 to 7, the results are close to the experimental results, but the closest total pressure and efficiency values are at mesh level 5. The results of this study can be a reference for research that simulates centrifugal fans.

Air and hydrogen injection tests on saturated compacted bentonite

Air and hydrogen injection tests on saturated compacted bentonite

The efficacy and safety of cupping as complementary and alternative therapy for metabolic syndrome: A systematic review and meta-analysis.

This systematic review and meta-analysis aimed to assess the efficacy and safety of cupping therapy in patients with metabolic syndrome (MetS). This systematic review focused on patients with MetS and included randomized controlled trials (RCTs) that compared the effects of cupping therapy with control groups. A total of 12 electronic databases were searched from inception until February 03, 2023. The main outcome after the meta-analysis was waist circumference; the others included anthropometric variables, blood pressure, lipid profile, fasting blood glucose level, and high-sensitivity C-reactive protein level. The incidence of adverse events and the follow-up courses were also evaluated. Risk of bias (ROB) was evaluated using ROB 2.0 from the Cochrane Handbook. This systematic review included five studies involving 489 patients. Some risks of bias were also identified. The meta-analysis revealed a statistically significance in waist circumference (MD = -6.07, 95% CI: -8.44 to -3.71, P < .001, I2 = 61%, τ2 = 3.4), body weight (MD = -2.46, 95% CI: -4.25 to -0.68, P = .007, I2 = 0%, τ2 = 0) and body mass index (MD = -1.26, 95% CI: -2.11 to -0.40, P = .004, I2 = 0%, τ2 = 0) between the cupping therapy and control groups. However, there were no significant results in total fat percentage and blood pressure values. Regarding biochemical markers, cupping significantly lowered the concentration of low-density lipoprotein cholesterol (MD = -3.98, 95% CI: -6.99 to -0.96, P = .010, I2 = 0%, τ2 = 0) but had no significant effect on total cholesterol, triglyceride, high-density lipoprotein cholesterol, fasting blood glucose, and high-sensitivity C-reactive protein. 3 RCTs reported no adverse events. Despite some ROB and low to substantial heterogeneity of the included studies, cupping therapy can be considered a safe and effective complementary intervention for reducing waist circumference, body weight, body mass index, and low-density lipoprotein cholesterol in patients with MetS. In the future, well-designed, high-quality, rigorous methodology, and long-term RCTs in this population are required to assess the efficacy and safety of cupping therapy.

Investigation of pressure gain characteristics of RDE with Tesla valve inlet scheme

Total pressure gain is one of the most significant performance metrics for rotating detonation engines. In this study, a Tesla valve is introduced with the intention of suppression of pressure feedback to improve the total pressure gain of RDE. A Tesla RDE has larger total pressure gain than a baseline RDE in some cases of 1.3Kg/s and 1.0Kg/s for A8/A3.2 of 0.25 because it can delay the onset of Longitudinal pulsed detonation (LPD). Compared with published data, kerosene/oxygen-enriched achieves slightly higher total pressure gain than gaseous fuels. The maximum total pressure gain measured using the Equivalent available pressure (EAP) is −6.84%. As injection stiffness decreases, total pressure gain increases towards zero. Injection stiffness tends to decrease with increasing velocity for the given mass flow rates of air and nozzle. The pressure of the combustor inlet is positively correlated with the product of the detonation wave velocity and the mass flux of the nozzle outlet. Values of outlet total pressure calculated using EAP and Mach corrected static pressure (MCSP) are nearly the same, and deviations of them are summarized. When the Mach number of the nozzle outlet and total pressure recovery coefficient are taken into consideration, MCSP decreases while EAP increases.

EVALUATION OF ENDOMETRIAL Bcl-2 EXPRESSION AND Ki-67 PROLIFERATIVE INDEX IN INFERTILE PATIENTS WITH AND WITHOUT POLYCYSTIC OVARY SYNDROME

Objective: In women of reproductive age, polycystic ovary syndrome (PCOS) is the most prevalent cause of infertility. The purpose of this study is to compare the Bcl-2 and Ki-67 values between infertile patients with and without PCOS.&#x0D; Material and methods: The study included twenty-seven infertile patients diagnosed with PCOS and another twenty-eight infertile patients who did not meet the criteria for PCOS. Smoking, pelvic infection symptoms, endometrial polyps and submucosal myomas during a transvaginal ultrasound, pituitary insufficiency, hyperprolactinemia, congenital adrenal hyperplasia, having had adnexal surgery and having a male factor that will result in infertility are all considered exclusion criteria. All patients' data were collected, including age, the length of their infertility, body mass index (BMI), waist-to-hip ratio (WHR), hirsutism score, blood pressure, total testosterone, triglyceride, total cholesterol, LDL, and HDL values, as well as Homa-IR and Hs-CRP readings. The pathology specialist in the examples evaluated Bcl-2 and Ki-67 levels.&#x0D; Results: We found that BMI, WHR, total testosterone level, blood pressure, total cholesterol, HOMA-IR, and hs-CRP values were significantly higher in infertile cases with PCOS. We also found that the Ki-67 and Bcl-2 values were higher in endometrial cells in sterile PCOS cases than in the control group. &#x0D; Conclusions: Ki-67 and Bcl-2 levels rise in PCOS patients, preventing apoptosis, limiting the formation of a suitable endometrial environment, and preventing embryo implantation. PCOS patients may frequently experience infertility and recurrent pregnancy losses. The cause of this problem may be the increased activity of estrogen. The primary treatment for PCOS will depend on further investigation into the variables affecting estrogen synthesis and GnRH release. The care plan should be built around this goal.

Temperature dependence of the absorption of the R(6) manifold of the 2ν3 band of methane in air in support of the MERLIN mission

Fifty nine high sensitivity spectra of the R(6) manifold of the 2ν3 band of methane in air, near 1.64 µm, have been recorded in support of the MERLIN mission. For this purpose, a cavity ring down spectrometer (CRDS) with a spectrally narrowed and stable (sub-kHz) laser source was coupled to a temperature regulated high-finesse optical cavity. The frequency scale of each spectrum was accurately determined from measurements of the beat note between a part of the laser light and the closest tooth of a frequency comb referenced to a rubidium clock. Series of spectra were recorded between 243 and 313 K with a 10 K temperature step. For each series, total pressure values of 50, 100, 250, 500 and 750 Torr were adopted. A multi-spectrum fitting procedure with the Hartmann-Tran (HT) line profile, including the first-order line-mixing parameter, has been used to derive the spectroscopic parameters for each of the six R(6) components, along with the temperature dependence of the line-shape parameters. The results show that the fitted effective model is able to reproduce the experimental spectra with a relative precision better than 0.2% for the entire R(6) manifold spectral region and better than 0.05% at the ON-line position of the MERLIN mission for the 250, 500 and 750 Torr spectra. The relative precision increases to 0.3% and the residuals at the ON-line position to 0.1% when including the 50 and 100 Torr spectra. Comparisons with ground-based atmospheric measurements show that these data significantly improve the modeling of methane absorption in this spectral region. The complete line list of the methane spectrum in the region of the R(6) manifold allowing notable improvement of the modeling of the absorption cross-section at the ON-line position of the MERLIN mission is provided as Supplementary Material.

Computational analysis on flow induced stress and acoustic vibration in a proposed silencer design for a three-cylinder in-line four-stroke spark ignition engine

Computational analysis of flowing exhaust gases inside a non-perforated silencer chamber of a commercially available three-cylinder inline four-stroke spark-ignition engine and in a modified perforated design was conducted and their respective levels of performance were predicted. Study on the existing and proposed silencer designs was carried out by way of computational fluid dynamics (CFD) analysis, structural analysis and modal analysis. Modal analysis has been performed in order to compute up to six fundamental frequencies on the aforementioned structure for analysing the response spectra for obtaining the natural frequencies at different modes of excitation. A reduction of 23.8% and 23.6% in the maximum values of static pressure and total pressure, respectively, has been observed for the proposed perforated model against the existing non-perforated silencer. The maximum acoustic power level and the maximum surface acoustic power level were found to be 9.5% and 7.3% respectively, less for the proposed design.

가상현실 체험을 위한 팬티 형태의 하네스 개발 및 하중 압력 고찰

Background/Objectives: Because the COVID-19 pandemic increases the time spent at home, the demand for active and active leisure life is steadily increasing. In particular, in the leisure and game industry, the demand for virtual-reality games combined with network technology is rapidly increasing from the desktop-type virtual-reality to active virtual reality experiences using various media and devices. Among these experiential activities, the basic equipment is mainly worn on the upper body, and the harness is worn on the lower body. However, conventional harnesses have problems as they are uncomfortable to wear and cause continuous pain.&#x0D; Methods: To improve the comfort and discomfort of the harness, a harness pattern was developed by predicting the load and pressure applied to the body using a three-dimensional (3D) virtual wearing system. After wearing the harness developed using the CLO 3D program virtual model, the clothing pressure in the flight state due to virtual wear was predicted and compared with the actual pressure distribution measured through experiments. For the experiment, pressure sensors were attached to the waist of a human mannequin to observe the change in the load and pressure distribution of the harness.&#x0D; Results: The total pressure value was very similar to the actual measured value as a result of comparing the pressure value measured the clothing pressure in the flight state due to virtual wear predicted in the CLO 3D program.&#x0D; Conclusion/Implications: Therefore, this study aims to improve the problem of existing harnesses by increasing the immersion of virthal-reality in various activities by suggesting the use of a panty-type harness that allows physical activity to be more free and distribute the instantaneously.

REALIZATION OF CONTINIOUSLY ROTATING DETONATION FOR SYNGAS-AIR MIXTURES

Numerical simulation of continuously rotating detonations (CRD) of stoichiometric two-fuel mixture with air has been carried out for the cylindrical annular detonation chamber (DC) of the rocket-type engine. Thesyngas (1 - α)óO + αH2, a binary mixture of hydrogen H2 and carbon monoxide CO, is taken as a fuel. The global flow structure in the DC and the detailed structure of the transverse detonation wave (TDW) front in thecontinuously rotating regime have been studied. Integral characteristics of the detonation process - the distribution of average values of static and total pressure along the length of the DC - and the value of specific impulse on the DC exit have been obtained. The regions of existence of stable CRD regime in coordinates “stagnation pressure pm - stagnation temperature Tm” in the injection manifold (receiver) have been determined. The minimal values of the DC length and radius for CRD for some regions at the pm-Tm plane have been found.

Computational fluid dynamics model to predict the dynamical behavior of the cerebrospinal fluid through implementation of physiological boundary conditions.

Cerebrospinal fluid (CSF) dynamics play an important role in maintaining a stable central nervous system environment and are influenced by different physiological processes. Multiple studies have investigated these processes but the impact of each of them on CSF flow is not well understood. A deeper insight into the CSF dynamics and the processes impacting them is crucial to better understand neurological disorders such as hydrocephalus, Chiari malformation, and intracranial hypertension. This study presents a 3D computational fluid dynamics (CFD) model which incorporates physiological processes as boundary conditions. CSF production and pulsatile arterial and venous volume changes are implemented as inlet boundary conditions. At the outlets, 2-element windkessel models are imposed to simulate CSF compliance and absorption. The total compliance is first tuned using a 0D model to obtain physiological pressure pulsations. Then, simulation results are compared with in vivo flow measurements in the spinal subarachnoid space (SAS) and cerebral aqueduct, and intracranial pressure values reported in the literature. Finally, the impact of the distribution of and total compliance on CSF pressures and velocities is evaluated. Without respiration effects, compliance of 0.17ml/mmHg yielded pressure pulsations with an amplitude of 5mmHg and an average value within the physiological range of 7-15mmHg. Also, model flow rates were found to be in good agreement with reported values. However, when adding respiration effects, similar pressure amplitudes required an increase of compliance value to 0.51ml/mmHg, which is within the range of 0.4-1.2ml/mmHg measured in vivo. Moreover, altering the distribution of compliance over the four different outlets impacted the local flow, including the flow through the foramen magnum. The contribution of compliance to each outlet was directly proportional to the outflow at that outlet. Meanwhile, the value of total compliance impacted intracranial pressure. In conclusion, a computational model of the CSF has been developed that can simulate CSF pressures and velocities by incorporating boundary conditions based on physiological processes. By tuning these boundary conditions, we were able to obtain CSF pressures and flows within the physiological range.

Effects of counterflow jet on the performance of a generic rocket at Mach 4 to 9

Effects of a jet emanating from the nose of a generic rocket in the opposite direction of the incoming freestream in reducing the drag and the heat loading of the rocket for flight Mach numbers 4 to 9 are reported. Computations to determine the counterflow jet total pressures that would result in most drag reduction are made for 40,000 ft (12,192 m) atmospheric conditions using an ideally expanded Mach 1.5 jet flow as the counterflow jet. In comparison to the baseline case, counterflow jet results in ∼20% reduction in drag at every Mach number studied. The area-weighted average surface temperature is also reduced by 30–70% with increasing flight Mach number.Additional computations were made using the jet total pressure that resulted in most drag reduction for the Mach 6 case to determine the effects of the jet total temperature on the area-weighted average surface temperature. For this purpose, the jet total temperature was varied between 300 and 1000 K. Results indicate that the area-weighted average surface temperature is reduced by 500 K even for jet total temperature of 1000 K.Computations were also made using the jet total pressure that resulted in most drag reduction for the Mach 6 case but for flight Mach numbers ranging from 4 to 9, while jet total temperature was kept as a constant at 500 K. Results indicate that use of a constant jet total pressure value results in 14–22% drag reduction with the peak reduction observed at Mach 6. Results also indicate that area-weighted average surface temperature is decreased by 33–50% with peak reduction observed at Mach 6.

Pineapple Drying Analysis in Packing Plants Through Computational Fluid Dynamics

The aim of this research is to determine the average fluid velocity values and the average total pressure at the outlet of the ventilation system conduit for the drying, by air impulsion, of pineapples in packing plants, in order to ensure the required humidity level of the crown for its proper packaging. The CAD model of the air conduction was obtained in Solidworks and Computational Fluid Dynamics (CFD) techniques were applied to simulate the performance of the ventilation system. Air was indicated as the type of fluid, and an internal analysis of the pipe with roughness Rz = 3.2 μm. As a computational domain, the pipeline was established, from the connection to the fan to the outlet diffuser. As boundary conditions were established; a W and Z Manufacturing regenerative fan at the inlet of the flow pipe 618,439 m3/h, and at the outlet of the pipe the value of atmospheric pressure. As a result of the simulation, an average velocity value at the diffuser outlet of 127.294 m/s was obtained, higher than the required 96.06 m/s. An average total pressure value of 111718.73 Pa was obtained in the conduit suitable for the proposed purposes. For the conveyor belt, it is recommended to use, in each row of pineapples, the simulated fan with a simple diffuser with a rectangular section of 1 x 20 cm, or a regenerative fan with a flow of 1248.77 m3/h and a diffuser with two-outlet bifurcation.

Studi Numerik Centrifugal Fan Tipe Impeller Backward dengan Variasi Putaran Fan

The primary air fan functions as a primary air producer which is used as air to transport coal powder from the pulverizer to the burner to be burned in the boiler furnace. This study aims to obtain the effect of the rotation variation of fan to fluid flow characteristics such as the distribution of total pressure, the dynamic pressure, the pressure static contours, velocity distribution, and the fan optimal efficiency. This study was numerical study with simulated a backward impeller type centrifugal fan in a two-dimension model using Fluid Computational software with the multiple reference frame method with the variation of fan rotation. Based on the visualization of the pressure contour and velocity distribution, it could be concluded that there was a volute phenomenon, this was indicated that the greater the volume area in the volute is the greater the total pressure value too. Based on the visualization of the outlet velocity distribution at the position of -0,8531m to -1,01301m, it was found that the velocity is close to the value of 0 m/s2. It showed that the minimum velocity in the area due to the volute tongue radius occurs a flow collision and it impacted the velocity in the area decreased up to V=0. From the simulation results, it was found that the greater the fan rotation value was the greater the efficiency value too. It would be verified by the actual operating data of the centrifugal fan with a minimum rotation range value of 1194 rpm to a maximum of 1468 rpm

Static Analysis of Unsteady Aerodynamics Wake of Simplified Helicopter Model Via Simulation Work

Computational tools have led and helped researchers in providing advanced results, notably in rotorcraft research, as flow around the helicopter is dominated by complex aerodynamics and flow interaction phenomena. This research work aimed to evaluate the aerodynamic computational results on a simplified model helicopter when the model was subjected to the angles of attack 0°, -5°, -15°, and -20°, respectively. The study also examined the unsteady flow behaviour on the three-dimensional elliptical shape of a fuselage equipped with a rotor hub of the single rotor blade. The computational domain for the aerodynamic flow field was created within the size of 7 m (length) x 5 m (width) x 5 m (height). Results showed that an increase in the angle of attack in the rotor component caused additional drag of about 34% to 45% whilst the fuselage component contributed about 55% to 65% to drag increment. Also, a significant value of total pressure from -235 Pa to 250 Pa demonstrated along the simplified model helicopter distinctly showed that the complexity of geometry caused adverse pressure. The findings of this research work could potentially improve the understanding of complex flow surrounding the helicopter that has always baffled the aerodynamicists.

Numerical study of continuously rotating detonation in two-fuel gaseous mixture

Numerical simulation of continuously rotating detonations of stoichiometric two-fuel mixture with air has been carried out for the cylindrical annular detonation chamber (DC) of the rocket-type engine. The syngas (1-α)СO+αH2, a binary mixture of hydrogen H2 and carbon monoxide CO, is taken. We studied the global flow structure in DC, and the detailed structure of the transverse wave (TW) front in the continuous rotating regime. Integral characteristics of the detonation process − the distribution of average values of static and total pressure along the length of the DC, and the value of specific impulse have been obtained. The region of existence of stable continuous detonation regime in coordinates of the stagnation pressure - temperature in injection manifold (receiver) and the geometric limit of stable TW have been determined.

CFD tool application in predicting the behavior of a centrifugal fan designed by one-dimensional theory

Computational fluid dynamics (CFD) is the most current technology in the fluid flow study. Experimental methods for predicting the turbomachinery performance involve greater time consumption and financial resources compared to the CFD approach. The purpose of this article is to present the analysis of CFD simulation results in a centrifugal fan. The impeller was calculated using the one-dimensional theory and the volute the principle of constant angular momentum. The ANSYS-CFX software was used for the simulation. The turbulence model adopted was the SST. The simulation provided the characteristic curves, the pressure and velocity distribution, and the static and total pressure values at impeller and volute exit. An analysis of the behavior of the pressure plots, and the loss and recovery of pressure in the volute was performed. The results indicated the characteristic curves, the pressure and velocity distribution were consistent with the turbomachinery theory. The pressure values showed the static pressure at volute exit was smaller than impeller exit for some flow rate. It caused the pressure recovery coefficient negative. This work indicated to be possible design a centrifugal fan applying the one-dimensional theory and optimize it with the CFD tool.