Research on the Applicability of Using a Curved Blade to Optimize the Flow Loss Weight Distribution of a Linear Compressor Cascade With Different Flow Separation Types

2018 ◽  
Author(s):  
Xiaoxu Kan ◽  
Songtao Wang ◽  
Lei Luo ◽  
Jiexian Su
Keyword(s):  
Flow Separation ◽  
Pressure Loss ◽  
Total Pressure ◽  
Loss Coefficient ◽  
Total Pressure Loss ◽  
Suction Surface ◽  
Pressure Loss Coefficient ◽  
Flow Loss ◽  
Curved Blade ◽  
Total Pressure Loss Coefficient

Due to the influence of an adverse pressure gradient, three types of flow separation occur on the suction surface of a linear compressor cascade: full-span open separation, corner closed separation and a corner stall condition. A numerical simulation was performed using a topological analysis method to determine the applicability of using a curved blade to improve the total pressure loss coefficient of a cascade with different types of flow separation situations on the suction surface. First, the accuracy of the ANSYS CFX program was verified against existing experimental data to balance the relationship between the calculation accuracy and the time savings. Second, the incidence characteristics of the cascade were analyzed to determine the incident conditions for three types of flow separation. Three factors of the cascade were considered to analyze a cascade with and without a curved blade: the transferring process of the topological structure on the blade suction surface, the evolution process of the vortex structure in the cascade passage and the weight distribution of the total pressure loss coefficient. The results indicate that the strength and scale of the concentrated shedding vortex (CSV) is distinctly reduced in the corner stall condition due to the influence of radial migration by the curved blade; thus, the flow loss is observably reduced. In the corner closed separation condition, the scale of the corner separation was too small to be notably reduced. In the full-span open separation condition, the curved blade not only reduced the total pressure loss coefficient but also increased the strength and scale of the passage vortex (PV). Finally, the curved blade method improved the applicability of reducing the flow loss in the corner stall condition and increased the stability and margin of a highly loaded compressor.

Numerical Investigation of Flow Separation Control of Low-Pressure High-Lift Blade With Different Grooves and Protrusions

2013 ◽  
Author(s):  
Huancheng Qu ◽  
Ping Li ◽  
Jianhui Chen ◽  
Zhongyang Shen ◽  
Yonghui Xie ◽  
...  
Keyword(s):  
Flow Separation ◽  
Pressure Loss ◽  
Total Pressure ◽  
Suction Side ◽  
Loss Coefficient ◽  
Total Pressure Loss ◽  
Flow Separation Control ◽  
Pressure Loss Coefficient ◽  
Flow Loss ◽  
Total Pressure Loss Coefficient

The shear stress transport (SST) turbulence model and γ-Reθ transition model were employed when solving the Reynolds-averaged Navier-Stokes (RANS) equations. The flow separation in the suction side of the typical high-lift low-pressure gas turbine PakB blade was investigated. Different sets of mesh were adopted and the results of grid independence study show that the precision is maintained when the grid system of 126,780 is adopted. And the computational results were compared with the existing experimental and computational results, which indicate that the numerical method can predict the separated transition flow reliably. Different kinds of structures including V grooves and protrusions, curved grooves and protrusions, rectangular grooves and protrusions were used to passive control of the flow separation in the suction side of the PakB blade. The structures have the same locations including 65%Cax, 68%Cax and 71%Cax on the suction side of the blade as well as length and height for better comparison. All of these cases are compared with the flow of PakB cascade without control with Re = 86,000 and FSTI = 1%. The shear layer is uplifted when the flow passes the passive device. And the separation bubble inside the grooves almost occupies the whole groove space which makes the length of the separation shorter than that in the case without control. The separation inside the grooves joins into the downstream separation in the case of grooves located in 71%Cax. The flow starts to separate in the leeside of the protrusion wherever the protrusion locates. And the attachment point moves forward significantly in the comparison with the case of without control. However, it brings in more flow loss because of the protrusion’s resistance to the boundary flow. In the total pressure loss coefficient comparison with the case without control, the grooves produce less flow loss while the protrusions at all the locations bring more flow loss. The nearer the groove is away from the separation point in the case without control, the higher the efficiency could be in the view of total pressure loss coefficient. The rectangular grooves are considered as a more effective structure for the flow separation control of PakB blade. Moreover, the flow separation bubble length and the total pressure loss coefficient decrease as Reynolds number increases in the cases without control. The total pressure loss coefficient in the different Reynolds numbers cases with rectangular groove is lower than that in the cases without control and the flow control performance gets much better when Reynolds number increases.

An Experimental Investigation of Contoured Leading Edges for Secondary Flow Loss Reduction

2004 ◽  
Author(s):  
Sandor Becz ◽  
Mark S. Majewski ◽  
Lee S. Langston
Keyword(s):  
Secondary Flow ◽  
Pressure Loss ◽  
Total Pressure ◽  
Leading Edge ◽  
Loss Coefficient ◽  
Total Pressure Loss ◽  
Loss Reduction ◽  
Pressure Loss Coefficient ◽  
Flow Loss ◽  
Total Pressure Loss Coefficient

Experimental results are presented which provide mass averaged total pressure loss coefficient measurements for three different turbine airfoil leading edge configurations. A baseline (Langston) configuration, a leading edge bulb, and a leading edge fillet were tested in a large-scale, low aspect ratio, high turning linear cascade. Results show that while the fillet geometry reduced overall loss by approximately 7%, the bulb did not exhibit a loss reduction. For the fillet, overall turning was slightly reduced, while for the bulb turning increased slightly. Thus, the bulb shows potential for increasing airfoil loading without an associated loss penalty. Contour plots of total pressure loss coefficient and vorticity are presented for all geometries and the major differences between each are discussed. Through investigation of pitch averaged loss profiles it is found that the area of greatest reduction differs between the bulb and fillet, leading to the possibility that the mechanisms through which each is affecting the flow may be different. This provides hope that the best features of each may potentially be combined to determine an optimum shape for secondary flow loss reduction.

Relationship Between Optimum Curved Blade Generate Line and Cascade Parameters in Subsonic Axial Compressor

2014 ◽  
Author(s):  
Jing Ling ◽  
Xin Du ◽  
Songtao Wang ◽  
Zhongqi Wang
Keyword(s):  
Aspect Ratio ◽  
Pressure Loss ◽  
Total Pressure ◽  
Loss Coefficient ◽  
Total Pressure Loss ◽  
Angle Variation ◽  
Pressure Loss Coefficient ◽  
Camber Angle ◽  
Curved Blade ◽  
Total Pressure Loss Coefficient

Curved blade has been widely used to reduce the endwall loss, but there is no criterion for curved blade design. Relationship of the optimum curved blade generate line (stack line) and the inlet Mach number, solidity, aspect ratio and camber angle in a linear compressor cascade were researched by optimization method in present paper. The stack line is vertically symmetrical, composed of two third-order Bezier curves and a straight line. The results show that total pressure loss coefficient decreases with the curved height increasing in the present calculate conditions at the same curved angle, and the optimum curved height is 0.5. The total pressure loss coefficient variation with curved angle presents a approximate parabola line type at the same curved height, there is an optimum curved angle, at which the total pressure loss coefficient is minimal. The optimum curved angle variation with the cascade parameters. Optimum curved angle increases with the inlet Ma and camber angle increasing, optimum curved angle variation with inlet Ma shows a polynomial curve type, optimum curved angle varied linearly with camber angle increasing. Optimum curved angle has little changes with solidity and aspect ratio increasing, optimum curved angle is about 6.5° in present conditions, but optimum curved angle will change with the blade loading. The benefit of the optimum curved blade increases with the inlet Mach number and camber angle increasing, and it has little change with solidity and aspect ratio increasing.

scholarly journals Preliminary Experimental Study on Pressure Loss Coefficients of Exhaust Manifold Junction

2014 ◽  
Vol 2014 ◽  
pp. 1-10
Author(s):  
Xiao-lu Lu ◽  
Kun Zhang ◽  
Wen-hui Wang ◽  
Shao-ming Wang ◽  
Kang-yao Deng
Keyword(s):  
Mass Flow ◽  
Pressure Loss ◽  
Total Pressure ◽  
Loss Coefficient ◽  
Total Pressure Loss ◽  
Flow Ratio ◽  
Pressure Loss Coefficient ◽  
Loss Coefficients ◽  
Total Pressure Loss Coefficient ◽  
Mass Flow Ratio

The flow characteristic of exhaust system has an important impact on inlet boundary of the turbine. In this paper, high speed flow in a diesel exhaust manifold junction was tested and simulated. The pressure loss coefficient of the junction flow was analyzed. The steady experimental results indicated that both of static pressure loss coefficientsL13andL23first increased and then decreased with the increase of mass flow ratio of lateral branch and public manifold. The total pressure loss coefficientK13always increased with the increase of mass flow ratio of junctions 1 and 3. The total pressure loss coefficientK23first increased and then decreased with the increase of mass flow ratio of junctions 2 and 3. These pressure loss coefficients of the exhaust pipe junctions can be used in exhaust flow and turbine inlet boundary conditions analysis. In addition, simulating calculation was conducted to analyze the effect of branch angle on total pressure loss coefficient. According to the calculation results, total pressure loss coefficient was almost the same at low mass flow rate of branch manifold 1 but increased with lateral branch angle at high mass flow rate of branch manifold 1.

Optimization of Tandem Blade Based on Improved Particle Swarm Algorithm

2016 ◽  
Author(s):  
Song Zhaoyun ◽  
Bo Liu ◽  
Mao Xiaochen ◽  
Lu Xiaofeng
Keyword(s):  
Particle Swarm Optimization ◽  
Pressure Loss ◽  
Total Pressure ◽  
Particle Swarm ◽  
Loss Coefficient ◽  
Total Pressure Loss ◽  
Swarm Optimization ◽  
Improved Particle Swarm Optimization ◽  
Pressure Loss Coefficient ◽  
Total Pressure Loss Coefficient

To improve the design quality of high-turning tandem blade, a coupling optimization system for the shape and relative position of tandem blades was developed based on an improved particle swarm optimization algorithm and NURBS parameterization. First of all, to increase convergence speed and avoid local optima of particle swarm optimization (PSO), an improved particle swarm optimization (IPSO) is formulated based on adaptive selection of particle roles, adaptive control of parameters and population diversity control. Then experiments are carried out using test functions to illustrate the performance of IPSO and to compare IPSO with some PSOs. The comparison indicates IPSO can obtain excellent convergence speed and simultaneously keep the best reliability. In addition, the coupling optimization system is validated by optimizing a large-turning tandem blade. Optimization results illustrate IPSO can obviously increase the optimization speed and reduce the time and cost of optimization. After optimization, at design condition, the total pressure loss coefficient of the optimized blade is decreased by 40.4%, and the static pressure ratio of optimized blade is higher and the total pressure loss coefficient is smaller at all incidence angles. In addition, properly reducing the gap area of tandem blade can effectively reduce the friction loss of the blade boundary layer and the mixing loss created by mixing the gap fluid and the mainstream fluid.

Active Separation Control in Circular and Transitioning S-Duct Diffusers Using Vortex Generator Jets

2006 ◽  
Author(s):  
A. M. Pradeep ◽  
R. K. Sullerey
Keyword(s):  
Pressure Loss ◽  
Total Pressure ◽  
Static Pressure ◽  
Vortex Generator ◽  
Loss Coefficient ◽  
Total Pressure Loss ◽  
Separation Control ◽  
Pressure Loss Coefficient ◽  
Distortion Coefficient ◽  
Total Pressure Loss Coefficient

Performance enhancement of three-dimensional S-duct diffusers by separation control using vortex generator jets is the objective of the current experimental investigation. Two different diffuser geometries namely, a circular diffuser and a rectangular–to–circular transitioning diffuser were studied in uniform inflow conditions at a Reynolds number of 7.8 × 105 and the performance evaluation of the diffusers was carried out in terms of static pressure improvement and quality (flow uniformity) of the exit flow. Detailed measurements that included total pressure, velocity distribution, surface static pressure, skin friction and boundary layer measurements were taken and these results are presented here in terms of static pressure rise, distortion coefficient and total pressure loss coefficient at the duct exit. The mass flow rate of the air injected through the VGJ was about 0.06 percent of the main flow for separation control. The distortion coefficient reduced by over 25 percent and the total pressure loss coefficient reduced by about 30 percent in both the diffusers. The physical mechanism of the flow control devices used has been explored using smoke visualization images.

Accurate Estimation of Profile Losses and Analysis of Loss Generation Mechanisms in a Turbine Cascade

2017 ◽  
Vol 139 (12) ◽  
Author(s):  
D. Lengani ◽  
D. Simoni ◽  
M. Ubaldi ◽  
P. Zunino ◽  
F. Bertini ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Pressure Loss ◽  
Total Pressure ◽  
Loss Coefficient ◽  
Total Pressure Loss ◽  
Accurate Estimation ◽  
Loss Mechanism ◽  
Pressure Loss Coefficient ◽  
Generation Mechanisms ◽  
Total Pressure Loss Coefficient

The paper analyzes losses and the loss generation mechanisms in a low-pressure turbine (LPT) cascade by proper orthogonal decomposition (POD) applied to measurements. Total pressure probes and time-resolved particle image velocimetry (TR-PIV) are used to determine the flow field and performance of the blade with steady and unsteady inflow conditions varying the flow incidence. The total pressure loss coefficient is computed by traversing two Kiel probes upstream and downstream of the cascade simultaneously. This procedure allows a very accurate estimation of the total pressure loss coefficient also in the potential flow region affected by incoming wake migration. The TR-PIV investigation concentrates on the aft portion of the suction side boundary layer downstream of peak suction. In this adverse pressure gradient region, the interaction between the wake and the boundary layer is the strongest, and it leads to the largest deviation from a steady loss mechanism. POD applied to this portion of the domain provides a statistical representation of the flow oscillations by splitting the effects induced by the different dynamics. The paper also describes how POD can dissect the loss generation mechanisms by separating the contributions to the Reynolds stress tensor from the different modes. The steady condition loss generation, driven by boundary layer streaks and separation, is augmented in the presence of incoming wakes by the wake–boundary layer interaction and by the wake dilation mechanism. Wake migration losses have been found to be almost insensitive to incidence variation between nominal and negative (up to −9 deg) while at positive incidence, the losses have a steep increase due to the alteration of the wake path induced by the different loading distribution.

Different Effects of Cantilevered and Shrouded Stators on Axial Compressor Performance

2017 ◽  
Author(s):  
Xiayi Si ◽  
Jinfang Teng ◽  
Xiaoqing Qiang ◽  
Jinzhang Feng
Keyword(s):  
Pressure Loss ◽  
Total Pressure ◽  
Loss Coefficient ◽  
Total Pressure Loss ◽  
Axial Position ◽  
Leakage Flow ◽  
Flow Angle ◽  
Design Point ◽  
Pressure Loss Coefficient ◽  
Total Pressure Loss Coefficient

Numerical simulations with the steady 3D RANS were performed on the rear stage of a modern high pressure compressor. The labyrinth seal cavity model of the shrouded stator was simplified according to the actual stator structure, which the seal cavity gap is 1% of blade height. Several typical configurations (shrouded stator, idealized stator and cantilevered stators) were designed and carried out, and cantilevered stators contained no gap, small gap (CS1%), design gap (CS2.5%) and large gap (CS4%/CS5%). The results indicate due to the effect of leakage flow from 1% span seal cavity gap, the total pressure loss of SS is larger than IS, while IS instead of SS in the process of the compressor design, the stall margin will be enlarged nearly 6% numerically. At the design point, when the hub gap is 3.5% span clearance CS has the same loss with IS, and when the hub gap is 4.5% span clearance CS has almost the same loss with SS. Among all operation range, the total pressure loss of S1 increases with the increase of the hub clearance. When the hub gap is 0 (CS0), there is no leakage flow and the loss is the least. At the design point, comparing with SS, the total pressure loss coefficient of CS0 decreases 18.34%, CS2.5% decreases 8.46% and IS decreases 6.45%. It means if the cantilevered stator with 2.5% span hub clearance were adopted in the HPC, the performance would be better than the shrouded stator. However, because of the matching condition, the rotor that follows after cantilevered stator should be redesigned according to blade loading and inlet flow angle changed. The performance of cantilevered stator is impacted of various hub clearance, the loss below 25% span increases significantly with hub clearance, the maximum value of outlet flow angle deviation is 2.3 degree. The stator hub peak loading is shifted upstream toward the leading edge when hub clearance size is increased. The total pressure loss coefficient and pressure coefficient at different axial position had the function relation. When the hub clearance increases, the position of double leakage flow start backwards, in the rear part of stator the secondary flow becomes stronger leading to more mixing loss and lower total pressure.

scholarly journals Investigation of Wash Fluid Preheating on the Effectiveness of Online Compressor Washing in Industrial Gas Turbines

2020 ◽  
Author(s):  
Roupa Agbadede ◽  
Biweri Kainga
Keyword(s):  
Gas Turbines ◽  
Pressure Loss ◽  
Total Pressure ◽  
Loss Coefficient ◽  
Total Pressure Loss ◽  
Compressor Cascade ◽  
Flow Angle ◽  
Pressure Loss Coefficient ◽  
Industrial Gas Turbines ◽  
Total Pressure Loss Coefficient

Abstract This study presents an investigation of wash fluid preheating on the effectiveness of online compressor washing in industrial gas turbines. Crude oil was uniformly applied on the compressor cascade blades surfaces using a roller brush, and carborundum particles were ingested into the tunnel to create accelerated fouled blades. Demineralized water was preheated to 500C using the heat coil provided in the tank. When fouled blades washed with preheated demineralized and the one without preheating were compared, it was observed that there was little or no difference in terms of total pressure loss coefficient and exit flow angle. However, when the fouled and washed cases were compared, there was a significant different in total pressure loss coefficient and exit flow angle.

Development of High-Efficiency Half-Ducted Propeller Fan for Air-Conditioners by Blade Tip Shape Modification

2019 ◽  
Author(s):  
Masashi Yoshikawa ◽  
Hiroyuki Toyoda ◽  
Hisashi Daisaka
Keyword(s):  
Pressure Loss ◽  
Total Pressure ◽  
Static Pressure ◽  
Leading Edge ◽  
Loss Coefficient ◽  
Total Pressure Loss ◽  
Trailing Edge ◽  
Pressure Loss Coefficient ◽  
Blade Tip ◽  
Total Pressure Loss Coefficient

Abstract We developed a high-efficiency half-ducted propeller fan to reduce the electric power consumption of the outdoor unit of air conditioner by using computational fluid dynamics (CFD). Total pressure loss coefficient on the cylindrical surface of blade tip started increasing at the middle of the blade, and the region of high total pressure loss coefficient was formed after trailing edge. Therefore, we assumed that decreasing this region helped increasing static pressure efficiency. Limiting stream lines on the pressure surface showed that the flow from leading edge leaked at the middle of the blade tip, so it was assumed that the region of the high total pressure loss coefficient arose from the leakage at the middle of the blade tip. We confirmed that static pressure at the middle of blade tip, which was the leakage point, was low. We assumed that low inward force to the flow caused the leakage. On the other hand, static pressure at trailing edge of the blade tip was high. Therefore, it was found that the inward force could be increased by making the static pressure higher at the meddle of the blade tip. In order to make the static pressure higher at the middle of the blade tip, we attempted to move the maximum camber position of the blade tip from trailing edge side to leading edge side. Calculation results showed leakage at the blade tip decreased and the static pressure efficiency increased by 0.5%. Experimental results showed that the static pressure efficiency increased by 1.7 % and sound pressure level was almost the same. For the above reasons, we found leakage of flow from leading edge could be decreased by adjusting the maximum camber position of the blade tip. Decreasing leakage contributed to increasing static pressure efficiency and decreasing electric power consumption.

Sign in / Sign up

Export Citation Format

Share Document