scholarly journals Performance Trends For Aerospikes & Supersonic Nozzles With Center-Bodies

2021 ◽  
Author(s):  
Bassel El-Dahr
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Specific Impulse ◽  
Working Fluid ◽  
Base Case ◽  
Conical Nozzle ◽  
Ansys Fluent ◽  
Supersonic Nozzles ◽  
Calculated Mass

The aim of this report is to examine performance trends for Aerospikes and Supersonic nozzles with center – bodies. The initial case that was tested is a convergent – divergent conical nozzle with a geometry and inlet flow conditions obtained from a NASA technical note. The technical note mentions that air was used as the working fluid for the nozzle. This case served as the base case for comparison with the performance of later nozzle designs. Nozzle flow for all the cases that were tested was simulated using ANSYS Fluent, for ambient conditions at 20km standard atmosphere. The convergent – divergent conical nozzle has the following calculated performance parameters using results from ANSYS Fluent: mass flow rate of 9.660 kg/s, axial Thrust of 10,583.5 N, and a specific impulse of 111.7s. All of the Supersonic nozzles with center – bodies have calculated specific impulse values lower than 111.7s by 0.4 – 1.6s, for approximately the same calculated mass flow rates as the base case. Adding a center – body to the original conical nozzle, was simply detrimental to performance. With regards to the Aerospike nozzles, 18 of them were tested. Aerospike 18 has the highest calculated specific impulse, at 115.3s for a calculated mass flow rate of 9.671kg/s. Aerospike 13 came in second at 114.6s, for a calculated mass flow rate of 9.676 kg/s. Several of the Aerospike designs did not out-perform the base case in terms of specific impulse. For those Aerospikes, the convergent – divergent section had a significantly lower thrust than the base case and the center – body was not able to over-compensate for the lower thrust. This report also looks at trends in thrust contribution by the convergent – divergent sections and center – bodies of Aerospikes at different nozzle geometries. The working fluid for all the cases tested in ANSYS Fluent including the base case, is air at a ratio of specific heats equal to 1.4.

scholarly journals Performance Trends For Aerospikes & Supersonic Nozzles With Center-Bodies

2021 ◽  
Author(s):  
Bassel El-Dahr
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Specific Impulse ◽  
Working Fluid ◽  
Base Case ◽  
Conical Nozzle ◽  
Ansys Fluent ◽  
Supersonic Nozzles ◽  
Calculated Mass

The aim of this report is to examine performance trends for Aerospikes and Supersonic nozzles with center – bodies. The initial case that was tested is a convergent – divergent conical nozzle with a geometry and inlet flow conditions obtained from a NASA technical note. The technical note mentions that air was used as the working fluid for the nozzle. This case served as the base case for comparison with the performance of later nozzle designs. Nozzle flow for all the cases that were tested was simulated using ANSYS Fluent, for ambient conditions at 20km standard atmosphere. The convergent – divergent conical nozzle has the following calculated performance parameters using results from ANSYS Fluent: mass flow rate of 9.660 kg/s, axial Thrust of 10,583.5 N, and a specific impulse of 111.7s. All of the Supersonic nozzles with center – bodies have calculated specific impulse values lower than 111.7s by 0.4 – 1.6s, for approximately the same calculated mass flow rates as the base case. Adding a center – body to the original conical nozzle, was simply detrimental to performance. With regards to the Aerospike nozzles, 18 of them were tested. Aerospike 18 has the highest calculated specific impulse, at 115.3s for a calculated mass flow rate of 9.671kg/s. Aerospike 13 came in second at 114.6s, for a calculated mass flow rate of 9.676 kg/s. Several of the Aerospike designs did not out-perform the base case in terms of specific impulse. For those Aerospikes, the convergent – divergent section had a significantly lower thrust than the base case and the center – body was not able to over-compensate for the lower thrust. This report also looks at trends in thrust contribution by the convergent – divergent sections and center – bodies of Aerospikes at different nozzle geometries. The working fluid for all the cases tested in ANSYS Fluent including the base case, is air at a ratio of specific heats equal to 1.4.

scholarly journals Modelling an unconventional closed-loop deep borehole heat exchanger (DBHE): sensitivity analysis on the Newberry volcanic setting

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Hannah R. Doran ◽  
Theo Renaud ◽  
Gioia Falcone ◽  
Lehua Pan ◽  
Patrick G. Verdin
Keyword(s):  
Sensitivity Analysis ◽  
Heat Exchanger ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Energy Flow ◽  
Closed Loop ◽  
Working Fluid ◽  
Valuable Insight ◽  
Deep Borehole

AbstractAlternative (unconventional) deep geothermal designs are needed to provide a secure and efficient geothermal energy supply. An in-depth sensitivity analysis was investigated considering a deep borehole closed-loop heat exchanger (DBHE) to overcome the current limitations of deep EGS. A T2Well/EOS1 model previously calibrated on an experimental DBHE in Hawaii was adapted to the current NWG 55-29 well at the Newberry volcano site in Central Oregon. A sensitivity analysis was carried out, including parameters such as the working fluid mass flow rate, the casing and cement thermal properties, and the wellbore radii dimensions. The results conclude the highest energy flow rate to be 1.5 MW, after an annulus radii increase and an imposed mass flow rate of 5 kg/s. At 3 kg/s, the DBHE yielded an energy flow rate a factor of 3.5 lower than the NWG 55-29 conventional design. Despite this loss, the sensitivity analysis allows an assessment of the key thermodynamics within the wellbore and provides a valuable insight into how heat is lost/gained throughout the system. This analysis was performed under the assumption of subcritical conditions, and could aid the development of unconventional designs within future EGS work like the Newberry Deep Drilling Project (NDDP). Requirements for further software development are briefly discussed, which would facilitate the modelling of unconventional geothermal wells in supercritical systems to support EGS projects that could extend to deeper depths.

scholarly journals Thermal Characteristics Analysis on Multi- Heat Pipe Induced Heat Exchanger

2019 ◽  
Vol 9 (2S2) ◽  
pp. 143-147 ◽  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Pipe ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Cold Water ◽  
Hot Water ◽  
Working Fluid ◽  
Physical Parameters

In this investigation of multi heat pipe induced in heat exchanger shows the developments in heat transfer is to improve the efficiency of heat exchangers. Water is used as a heat transfer fluid and acetone is used as a working fluid. Rotameter is set to measure the flow rate of cold water and hot water. To maintain the parameter as experimental setup. Then set the mass flow rate of hot water as 40 LPH, 60LPH, 80 LPH, 100LPH, 120 LPH and mass flow rate of cold water as 20 LPH, 30 LPH, 40 LPH, 50 LPH, and 60 LPH. Then 40 C, 45 ºC, 50 ºC, 55 C, 60 ºC are the temperatures of hot water at inlet are maintained. To find some various physical parameters of Qc , hc , Re ,, Pr , Rth. The maximum effectiveness of the investigation obtained from condition of Thi 60 C, Tci 32 C and 100 LPH mhi, 60 LPH mci the maximum effectiveness attained as 57.25. Then the mhi as 100 LPH, mci as 60 LPH and Thi at 40 C as 37.6%. It shows the effectiveness get increased about 34.3 to the maximum conditions.

Aerodynamic Performance Evaluation of Axial Flow Fan Using Numerical Techniques

2021 ◽  
Author(s):  
Raghuvaran D. ◽  
Satvik Shenoy ◽  
Srinivas G
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Rotational Speed ◽  
Total Pressure ◽  
Axial Flow ◽  
High Mass ◽  
Ansys Fluent ◽  
Industrial Sectors ◽  
Mass Flow Rates

Abstract Axial flow fans (AFF) are extensively used in various industrial sectors, usually with flows of low resistance and high mass flow rates. The blades, the hub and the shroud are the three major parts of an AFF. Various kinds of optimisation can be implemented to improve the performance of an AFF. The most common type is found to be geometric optimisation including variation in number of blades, modification in hub and shroud radius, change in angle of attack and blade twist, etc. After validation of simulation model and carrying out a grid independence test, parametric analysis was done on an 11-bladed AFF with a shroud of uniform radius using ANSYS Fluent. The rotational speed of the fan and the velocity at fan inlet were the primary variables of the study. The variation in outlet mass flow rate and total pressure was studied for both compressible and incompressible ambient flows. Relation of mass flow rate and total pressure with inlet velocity is observed to be linear and exponential respectively. On the other hand, mass flow rate and total pressure have nearly linear relationship with rotational speed. A comparison of several different axial flow tracks with the baseline case fills one of the research gaps.

Effects of Fe3O4/Water Nanofluid on the Efficiency of a Curved Pipe

2019 ◽  
Vol 11 (4) ◽  
Author(s):  
Milad Kelidari ◽  
Ali Jabari Moghadam
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Volume Concentration ◽  
Volume Fraction ◽  
Working Fluid ◽  
Radius Of Curvature ◽  
Dean Number ◽  
Curved Pipe ◽  
Overall Efficiency

Different-radius of curvature pipes are experimentally investigated using distilled water and Fe3O4–water nanofluid with two different values of the nanoparticle volume fraction as the working fluids. The mass flow rate is approximately varied from 0.2 to 0.7 kg/min (in the range of laminar flow); the wall heat flux is nearly kept constant. The experimental results reveal that utilizing the nanofluid increases the convection heat transfer coefficient and Nusselt number in comparison to water; these outcomes are also observed when the radius of curvature is decreased and/or the mass flow rate is increased (equivalently, a rise in Dean number). The resultant pressure gradient is, however, intensified by an increase in the volume concentration of nanoparticles and/or by a rise in Dean number. For any particular working fluid, there is an optimum mass flow rate, which maximizes the system efficiency. The overall efficiency can be introduced to include hydrodynamic as well as thermal characteristics of nanofluids in various geometrical conditions. For each radius of curvature, the same overall efficiency may be achieved for two magnitudes of nanofluid volume concentration.

scholarly journals Comparison of Swing and Tilting Check Valves Flowing Compressible Fluids

Micromachines ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 758
Author(s):  
Zhi-xin Gao ◽  
Ping Liu ◽  
Yang Yue ◽  
Jun-ye Li ◽  
Hui Wu
Keyword(s):  
Mach Number ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Check Valve ◽  
Small Mass ◽  
Working Fluid ◽  
Valve Disc ◽  
Valve Opening ◽  
The Difference

Although check valves have attracted a lot of attention, work has rarely been completed done when there is a compressible working fluid. In this paper, the swing check valve and the tilting check valve flowing high-temperature compressible water vapor are compared. The maximum Mach number under small valve openings, the dynamic opening time, and the hydrodynamic moment acting on the valve disc are chosen to evaluate the difference between the two types of check valves. Results show that the maximum Mach number increases with the decrease in the valve opening and the increase in the mass flow rate, and the Mach number and the pressure difference in the tilting check valve are higher. In the swing check valve, the hydrodynamic moment is higher and the valve opening time is shorter. Furthermore, the valve disc is more stable for the swing check valve, and there is a periodical oscillation of the valve disc in the tilting check valve under a small mass flow rate.

Three-Dimensional Fluid Dynamics and Radiative Heat Transfer Modeling of a Small Particle Solar Receiver

2013 ◽  
Author(s):  
Pablo Fernández del Campo ◽  
Fletcher Miller ◽  
Adam Crocker
Keyword(s):  
Heat Transfer ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Small Particle ◽  
Radiative Heat ◽  
Three Dimensional ◽  
Solar Irradiation ◽  
Ansys Fluent ◽  
Solar Receiver

We present an investigation of the effects of the solar irradiation and mass flow conditions on the behavior of a Small Particle Solar Receiver employing our new, three-dimensional coupled fluid flow and radiative heat transfer model. This research expands on previous work conducted by our group and utilizes improved software with a set of new features that allows performing more flexible simulations and obtaining more accurate results. For the first time, it is possible not only to accurately predict the overall efficiency and the wall temperature distribution of the solar receiver, but also to determine the effect on the receiver of the window, the outlet tube, real solar irradiation from a heliostat field, non-cylindrical geometries and 3-D effects. This way, a much better understanding of the receiver’s capabilities is obtained. While the previous models were useful to observe simple trends, this new software is flexible and accurate enough to eventually act as a design and optimization tool for the actual receiver. The solution procedure relies on the coupling of the CFD package ANSYS Fluent to our in-house Monte Carlo Ray Trace (MCRT) software. On the one hand, ANSYS Fluent is utilized as the mass-, momentum- and energy-equation solver and requires the divergence of the radiative heat flux, which constitutes a source term of the energy equation. On the other hand, the MCRT software calculates the radiation heat transfer in the solar receiver and needs the temperature field to do so. By virtue of the coupled nature of the problem, both codes should provide feed-back to each other and iterate until convergence. The coupling between ANSYS Fluent and our in-house MCRT code is done via User-Defined Functions. After developing the mathematical model, setting up and validating the software, and optimizing the coupled solution procedure, the receiver has been simulated under fifteen different solar irradiation and mass flow rate cross combinations. Among other results, the behavior of the receiver at different times of the day and the optimum mass flow rate as a function of the solar thermal input are presented. On an average day, the thermal efficiency of the receiver is found to be over 89% and the outlet temperature over 1250 K at all times from 7:30 AM to 4:00 PM (Albuquerque, NM) by properly adapting the mass flow rate. The origin of the losses and how to improve the efficiency of the Small Particle Solar Receiver are discussed as well.

scholarly journals The Preliminary Design of Radial Inflow Turbines

1989 ◽  
Author(s):  
A. Whitfield
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
State Of The Art ◽  
Turbine Rotor ◽  
Working Fluid ◽  
Preliminary Design ◽  
Power Ratio ◽  
Mach Numbers ◽  
Absolute Dimensions

A procedure is described which develops the non-dimensional design of a radial inflow turbine rotor. The design is developed, for any specified non-dimensional power ratio, with the objective of minimising the inlet and discharge Mach numbers so that the passage losses are minimised. Initially state of the art efficiencies are assumed but are later modified through the specification of empirical losses. The resultant non-dimensional design can be transformed to absolute dimensions through the specification of the inlet stagnation conditions and the mass flow rate of the working fluid.

The Preliminary Design of Radial Inflow Turbines

1990 ◽  
Vol 112 (1) ◽  
pp. 50-57 ◽  
Author(s):  
A. Whitfield
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
State Of The Art ◽  
Turbine Rotor ◽  
Working Fluid ◽  
Preliminary Design ◽  
Power Ratio ◽  
Mach Numbers ◽  
Absolute Dimensions

A procedure is described that develops the nondimensional design of a radial inflow turbine rotor. The design is developed, for any specified nondimensional power ratio, with the objective of minimizing the inlet and discharge Mach numbers so that the passage losses are minimized. Initially state-of-the-art efficiencies are assumed, but these are later modified through the specification of empirical losses. The resultant nondimensional design can be transformed to absolute dimensions through the specification of the inlet stagnation conditions and the mass flow rate of the working fluid.

Dynamic Behavior and Off-Design Performance Analysis of Solar Driven ORC Using Scroll Expanders

2019 ◽  
Author(s):  
Ying Zhang ◽  
Arun Kumar Narasimhan ◽  
Mengjie Bai ◽  
Li Zhao ◽  
Shuai Deng ◽  
...  
Keyword(s):  
Experimental Data ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
System Level ◽  
Working Fluid ◽  
Small Scale ◽  
Solar Insolation ◽  
Design Performance ◽  
Fluid Mass

Abstract Solar driven ORC system is a possible solution for small-scale power generation. A scroll expander is considered due to its better suitability among other positive displacement expanders for small-scale power outputs. This work conducted a test of an ORC system with an expansion valve by varying the working fluid mass flow rate in two scenarios. A dynamic system-level model of ORC was developed and validated with experimental data. The validated model was used to predict the ORC performance considering off-design conditions of expander and solar insolation. The experimental data showed that pressures and temperatures exhibited the same trend as that of the working fluid mass flow rate, of which the evaporation pressure was the most sensitive to this variation. The simulation results are in good agreement with the experimental results. Results from the dynamic model showed that the ORC power output was underestimated by up to 54.7%, when off-design performance of expander was not considered. Considering the expander off-design performance and solar insolation, a highest thermal efficiency of 7.6% and an expander isentropic efficiency of 80.6% were achieved.

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