Outlet Surface Area Influence in Spiral Casing Design on Centrifugal Fan Performance

2020 ◽  
Vol 5 (1) ◽  
pp. 37-41
Author(s):  
Ardit Gjeta ◽  
Lorenc Malka
Keyword(s):  
Surface Area ◽  
Static Pressure ◽  
Total Efficiency ◽  
Centrifugal Fan ◽  
Recovery Coefficient ◽  
Fan Performance ◽  
Parameter Variations ◽  
Set Up ◽  
Spiral Casing ◽  
Pressure Recovery Coefficient

In this paper, the effect of the outlet surface area of the spiral casing on the performance of a centrifugal fan was investigated using open source CFD software OpenFOAM [1]. An automized loop with RANS and data post-processing is set up using Matlab, for allowing a large number of parameter variations. The effect was analyzed as a function of total pressure loss and static pressure recovery coefficient and on total efficiency as well.

scholarly journals Effect of Clearance Gap in Spiral Casing Design of a Centrifugal Fan with Optimized Impellers

2019 ◽  
Vol 4 (9) ◽  
pp. 181-185
Author(s):  
Ardit Gjeta
Keyword(s):  
Total Pressure ◽  
Static Pressure ◽  
Geometrical Parameters ◽  
Centrifugal Fan ◽  
Recovery Coefficient ◽  
Parameter Variations ◽  
Set Up ◽  
Operating Points ◽  
Spiral Casing ◽  
Pressure Recovery Coefficient

Industrial fans are subject to European Union energy labeling and Ecodesign requirements. By using more efficient industrial fans, Europe will save 34 TWh and avoid 16 million tones of CO2 emissions annually by 2020 [1]. In this paper, the effect of the clearance gap between the impeller and the volute, on the performance of a centrifugal fan was investigated using open source CFD software OpenFOAM [2]. An automized loop with RANS and data post-processing is set up using Matlab, for allowing a large number of parameter variations. We conducted numerical analysis for all operating points, where starting points are optimal impellers for the whole range of specific speeds [3], [4]. The effect of volute angle and geometrical parameters related to the tongue [5], on total pressure loss, static pressure recovery coefficient and on efficiency are presented.

Effect of the turning angle on the flow and performance characteristics of long S-shaped circular diffusers

2003 ◽  
Vol 217 (1) ◽  
pp. 29-41 ◽  
Author(s):  
R B Anand ◽  
L Rai ◽  
S N Singh
Keyword(s):  
Total Pressure ◽  
Static Pressure ◽  
Area Ratio ◽  
Secondary Flows ◽  
Performance Characteristics ◽  
Pressure Recovery ◽  
Recovery Coefficient ◽  
Turning Angle ◽  
And Performance ◽  
Pressure Recovery Coefficient

The effect of the turning angle on the flow and performance characteristics of long S-shaped circular diffusers (length-inlet diameter ratio, L/Di = 11:4) having an area ratio of 1.9 and centre-line length of 600 mm has been established. The experiments are carried out for three S-shaped circular diffusers having angles of turn of 15°/15°, 22.5°/22.5° and 30°/30°. Velocity, static pressure and total pressure distributions at different planes along the length of the diffusers are measured using a five-hole impact probe. The turbulence intensity distribution at the same planes is also measured using a normal hot-wire probe. The static pressure recovery coefficients for 15°/15°, 22.5°/22.5° and 30°/30° diffusers are evaluated as 0.45, 0.40 and 0.35 respectively, whereas the ideal static pressure recovery coefficient is 0.72. The low performance is attributed to the generation of secondary flows due to geometrical curvature and additional losses as a result of the high surface roughness (~0.5 mm) of the diffusers. The pressure recovery coefficient of these circular test diffusers is comparatively lower than that of an S-shaped rectangular diffuser of nearly the same area ratio, even with a larger turning angle (90°/90°), i.e. 0.53. The total pressure loss coefficient for all the diffusers is nearly the same and seems to be independent of the angle of turn. The flow distribution is more uniform at the exit for the higher angle of turn diffusers.

Some Studies on Low Solidity Vaned Diffusers of a Centrifugal Compressor Stage

2005 ◽  
Author(s):  
T. Ch. Siva Reddy ◽  
G. V. Ramana Murty ◽  
Prasad Mukkavilli ◽  
D. N. Reddy
Keyword(s):  
Centrifugal Compressor ◽  
Static Pressure ◽  
Pressure Ratio ◽  
Pressure Recovery ◽  
Compressor Stage ◽  
Recovery Coefficient ◽  
Vaned Diffuser ◽  
Flow Angle ◽  
Centrifugal Compressor Stage ◽  
Pressure Recovery Coefficient

Numerical simulation of impeller and low solidity vaned diffuser (LSD) of a centrifugal compressor stage is performed individually using CFX- BladeGen and BladeGenPlus codes. The tip mach number for the chosen study was 0.35. The same configuration was used for experimental investigation for a comparative study. The LSD vane is formed using standard NACA profile with marginal modification at trailing edge. The performance parameters obtained form numerical studies at the exit of impeller and the diffuser have been compared with the corresponding experimental data. These parameters are pressure ratio, polytropic efficiency and flow angle at the impeller exit where as the parameters those have been compared at the exit of diffuser are the static pressure recovery coefficient and the exit flow angle. In addition, the numerical prediction of the blade loading in terms of blade surface pressure distribution on LSD vane has been compared with the corresponding experimental results. Static pressure recovery coefficient and flow angle at diffuser exit is seen to match closely at higher flows. The difference at lower flows could be due to the effect of interaction between impeller and diffuser combinations, as the numerical analysis was done separately for impeller and diffuser and the effect of impeller diffuser interaction was not considered.

A Preliminary Study of Annular Diffusers With Constant Diameter Outer Walls (Suitable for Turbine Exits)

1983 ◽  
Author(s):  
R. C. Adkins ◽  
O. H. Jacobsen ◽  
P. Chevalier
Keyword(s):  
Static Pressure ◽  
Short Length ◽  
Pressure Recovery ◽  
Recovery Coefficient ◽  
Constant Diameter ◽  
Preliminary Study ◽  
Pressure Recovery Coefficient

A systemmatic series of tests has been conducted on a family of annular diffusers where the outer casing is maintained at constant diameter. Such a diffuser is typical of turbine exits. Data, in the form of static pressure recovery coefficient is plotted against diffuser length for several different designs of centerbody closure. It has been shown that such diffusers can have short length centerbodies for which a set of design guides has been established.

Numerical Investigations on the Aerodynamic Performance of Last Stage – Exhaust Hood for Steam Turbines

2011 ◽  
Author(s):  
Rui Yang ◽  
Jiandao Yang ◽  
Zeying Peng ◽  
Liqun Shi ◽  
Aping He ◽  
...  
Keyword(s):  
Working Conditions ◽  
Static Pressure ◽  
Aerodynamic Performance ◽  
Pressure Recovery ◽  
Computational Domain ◽  
Steam Turbines ◽  
Exhaust Hood ◽  
Recovery Coefficient ◽  
Last Stage ◽  
Pressure Recovery Coefficient

The aerodynamic performance and internal flow characteristics of the last stage and exhaust hood for steam turbines is numerically investigated using the Reynolds-Averaged Navier-Stokes (RANS) solutions based on the commercial CFD software ANSYS CFX. The full last stage including 66 stator blades and 64 rotor blades coupling with the exhaust hood is selected as the computational domain. The aerodynamic performance of last stage and static pressure recovery coefficient of exhaust hood at five different working conditions is conducted. The interaction between the last stage and exhaust hood is considered in this work. The effects of the non-uniform aerodynamic parameters along the rotor blade span on the static pressure recovery coefficient of the non-symmetric geometry of the exhaust hood are studied. The numerical results show that the efficiency of the last stage has the similar values ranges from 89.8% to 92.6% at different working conditions. In addition, the similar static pressure recovery coefficient of the exhaust hood was observed at five working conditions. The excellent aerodynamic performance of the exhaust hood was illustrated in this work.

Aerodynamic Optimization Design of Exhaust Hood Diffuser for Steam Turbine With Three-Dimensional Reynolds-Averaged Navier-Stokes Solutions

2014 ◽  
Author(s):  
Jiandao Yang ◽  
Taowen Chen ◽  
Jun Li ◽  
Zhenping Feng
Keyword(s):  
Optimization Design ◽  
Static Pressure ◽  
Three Dimensional ◽  
Aerodynamic Performance ◽  
Navier Stokes ◽  
Exhaust Hood ◽  
Aerodynamic Optimization ◽  
Recovery Coefficient ◽  
Last Stage ◽  
Pressure Recovery Coefficient

Combined with three-dimensional parameterization method of exhaust diffuser profile, aerodynamic performance evaluation method, response surface approximation evaluation model and Hooke-Jeeves direct search approach, aerodynamic optimization design of exhaust hood diffuser for steam turbine is presented. The aerodynamic performance of exhaust hood design candidate is evaluated using three-dimensional Reynolds-Averaged Navier-Stokes (RANS) solutions. Aerodynamic optimization design of exhaust hood is conducted for the maximum of the static pressure recovery coefficient of exhaust hood. The design variables are specified by the exhaust diffuser profile parameterization method. The aerodynamic performance of the optimized exhaust hood and referenced design is numerically calibrated with consideration of the full last stage and rotor tip clearance. The static pressure recovery coefficient of the optimized exhaust hood is higher than that of the referenced design with consideration of the upstream last stage influence. Furthermore, the detailed flow pattern of the optimized exhaust hood and referenced design is also analyzed and compared.

Effects of casing angle on the performance of parallel hub axial annular diffuser

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Hardial Singh ◽  
B.B. Arora
Keyword(s):  
Static Pressure ◽  
Swirling Flow ◽  
Pressure Recovery ◽  
Recovery Coefficient ◽  
Pressure Loss Coefficient ◽  
Swirl Angle ◽  
Annular Diffuser ◽  
Inlet Swirl ◽  
Total Pressure Loss Coefficient ◽  
Pressure Recovery Coefficient

Abstract In this paper, the effects of non-swirling and swirling flow on the performance of parallel hub axial annular diffuser has been investigated. The study was conducted on a fully developed swirling flow and non-swirling flow to predict the separation of the flow from the wall. Three different annular diffusers were used with casing wall angles of 3°, 6°, and 9°. Furthermore, various swirl angles (0–25°) at the inlet of diffusers have been investigated to analyze the performance across the length. It was found that parallel hub axial annular diffuser performance increases up to a certain length as the inlet swirl angle increases. However, the performance also improves as the diffuser area ratio (AR) increases. The performance is evaluated based on the static pressure recovery coefficient (Cp) and the total pressure loss coefficient (CTL). The highest possible pressure recovery is achieved by the 12° swirl angle with a casing angle of 6°.

CFD Analysis of a Centrifugal Compressor Impeller and Volute

1999 ◽  
Author(s):  
Harri Pitkänen ◽  
Hannu Esa ◽  
Petri Sallinen ◽  
Jaakko Larjola
Keyword(s):  
Centrifugal Compressor ◽  
Static Pressure ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Prediction Method ◽  
Navier Stokes ◽  
Recovery Coefficient ◽  
Compressor Impeller ◽  
Compressor Performance ◽  
Pressure Recovery Coefficient

In this study, centrifugal compressor performance was predicted using CFD. Three-dimensional time-averaged impeller and volute simulations were performed using a Navier–Stokes code. The presented performance prediction method has been divided into three phases. Firstly, the impeller was calculated with a vaneless diffuser. That gives inlet boundary conditions for the volute analysis and the pressure ratio at the diffuser exit. Next, the volute analysis was performed and a static pressure recovery coefficient obtained. Finally, that result was combined with the pressure ratio prediction from the impeller analysis, and the overall compressor performance thus obtained.

Flow Characteristics in a Large Area Ratio Curved Diffuser

1996 ◽  
Vol 210 (1) ◽  
pp. 65-75 ◽  
Author(s):  
B Majumdar ◽  
S N Singh ◽  
D P Agrawal
Keyword(s):  
Turbulence Intensity ◽  
Marked Improvement ◽  
Static Pressure ◽  
Flow Characteristics ◽  
Flow Distribution ◽  
Area Ratio ◽  
Large Area ◽  
Recovery Coefficient ◽  
Convex Wall ◽  
Pressure Recovery Coefficient

Flow characteristics in a large area ratio curved diffuser (AR = 3.4, Δβ = 90°, AS = 0.685) have been experimentally evaluated with splitter vanes installed at different angles to the flow at the inlet of the diffuser. The splitter vanes deflect the flow towards the convex wall and simultaneously increase the turbulence intensity. A marked improvement in flow distribution inside the diffuser and a significant increase in the static pressure recovery coefficient are obtained with splitter vanes at a 10° angle.

Numerical Investigation of Vaneless Diffuser by Pinching and Rotation

2019 ◽  
Author(s):  
Porika Niveditha ◽  
Bhamidi V. S. S. S. Prasad
Keyword(s):  
Pressure Loss ◽  
Static Pressure ◽  
Stagnation Pressure ◽  
Pressure Recovery ◽  
Vaneless Diffuser ◽  
Recovery Coefficient ◽  
Pressure Loss Coefficient ◽  
Energy Coefficient ◽  
Pressure Recovery Coefficient ◽  
Isentropic Efficiency

Abstract Non-conventional diffuser designs are introduced to minimize the energy losses associated with diffusion and to enhance stable operating range of the diffusion system. This is achieved by reducing width of the diffuser by modifying a hub or shroud curves by keeping the diffuser diameter ratio constant which is often known as pinch. The comparison of modified compressor with base model is accomplished by using performance characteristics such as static pressure recovery coefficient, stagnation pressure loss coefficient, energy coefficient and isentropic efficiency. Simulations are performed at various hub pinch (5%–20%), shroud pinch (5%–20%) and combined hub and shroud pinch (5%–20%). Among all the cases shroud pinch of 10% shows best results in terms of stagnation pressure loss coefficient, static pressure recovery coefficient and energy coefficient. Further, simulations are carried out with forced rotating vaneless diffuser. It gives better results in terms of pressure rise with lower stagnation pressure losses. But there is a moderate decrement in isentropic efficiency of compressor when compared to the base model.

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