Aerodynamic and Performance Behavior of a Radial Turbine at Design and Off-Design Conditions

2016 ◽  
Author(s):  
Cheng Zhu ◽  
Weilin Zhuge ◽  
Yangjun Zhang ◽  
Jie Peng
Keyword(s):  
High Altitude ◽  
Flow Characteristics ◽  
Leading Edge ◽  
Suction Side ◽  
Expansion Ratio ◽  
Turbine Efficiency ◽  
High Altitude Area ◽  
Ratio Condition ◽  
And Performance ◽  
Supersonic Zone

When a turbocharged engine which was designed to work at sea level works at high altitude area, its power will decrease because of the decrease of the air density. And the expansion ratio of the turbine will increase a lot because of the decrease of the out pressure, leading to a bad efficiency of the turbine. In order to recover the power of the turbocharged engine when it worked at the high altitude area, the efficiency of the turbine should be increased when it worked at high expansion ratio condition. This paper shows a numerical investigation of the flow fields in a radial inflow turbine at design and off design condition. The comparison of the flow characteristics between the design and off design conditions is researched. When the turbine work at a high expansion ratio, there will occur a supersonic zone at the leading edge on the suction side and a shock wave will occur at the trailing edge, causing a flow separation and making a lot of losses, leading the decrease of the turbine efficiency.

scholarly journals Performance and Exit Flow Characteristics of Mixed-Flow Turbines

1997 ◽  
Vol 3 (4) ◽  
pp. 277-293 ◽  
Author(s):  
C. Arcoumanis ◽  
R. F. Martinez-Botas ◽  
J. M. Nouri ◽  
C. C. Su
Keyword(s):  
Steady State ◽  
Velocity Ratio ◽  
Tangential Velocity ◽  
Flow Characteristics ◽  
Mixed Flow ◽  
Cross Sectional ◽  
Flow Angle ◽  
Turbine Efficiency ◽  
And Performance ◽  
Inlet Angle

The performance and exit flow characteristics of two mixed-flow turbines have been investigated under steady-state conditions. The two rotors differ mainly in their inlet angle geometry, one has a nominal constant incidence (rotor B) and the other has a constant blade angle (rotor C), but also in the number of blades. The results showed that the overall peak efficiency of rotor C is higher than that of rotor B. Two different volutes were also used for the tests, differing in their cross-sectional area, which confirm that the new larger area volute turbine has a higher efficiency than the old one, particularly at lower speeds, and a fairly uniform variation with velocity ratio.The flow exiting the blades has been quantified by laser Doppler velocimetry. A difference in the exit flow velocity for rotors B and C with the new volute was observed which is expected given their variation in geometry and performance. The tangential velocities near the shroud resemble a forced vortex flow structure, while a uniform tangential velocity component was measured near the hub. The exit flow angles for both rotor cases decreased rapidly from the shroud to a minimum value in the annular core region before increasing gradually towards the hub. In addition, the exit flow angles with both rotors were reduced with increasing rotational speeds. The magnitude of the absolute flow angle was reduced in the case of rotor C, which may explain the improved steady state performance with this rotor. The results also revealed a correlation between the exit flow angle and the performance of the turbines; a reduction in flow angle resulted in an increase in the overall turbine efficiency.

Numerical Study on Heat Transfer and Flow Characteristics in Double Turning Areas Ribbed Serpentine Channel With Lateral Outflow

2019 ◽  
Author(s):  
Bo-lun Zhang ◽  
Hui-ren Zhu ◽  
Tao Guo ◽  
Chun-yi Yao ◽  
Zhong-yi Fu
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Numerical Study ◽  
Pressure Coefficient ◽  
Flow Characteristics ◽  
Suction Side ◽  
Pressure Side ◽  
Maximum Increase ◽  
Serpentine Channel ◽  
Ratio Condition

Abstract The double turning areas ribbed serpentine channel with lateral outflow is an important structure for designing the internal systems of turbine blade. The current work similarly simplifies the internal channel of the real blade. The Nusselt number and pressure coefficient distribution of the double turning areas ribbed serpentine channel with different outflow ratios are numerically researched under static and rotating conditions. The Realizable k-ε turbulence model with enhanced wall treatment is used in the numerical simulation. The inlet Reynolds number is 11000. The rotation numbers vary from 0 to 0.09. Three outflow ratios are 27%/0%/73%, 27%/49%/24% and 27%/73%/0%, respectively. The rotation radius (R) is 46.4d. The result shows that the Nusselt number distribution of the passage 3 under 27%/49%/24% outflow ratio condition is similar to that under 27%/73%/0% outflow ratio condition. There is a large low Nusselt number area in the passage 3 under Dr = 27%/0%/73% condition. The averaged area Nusselt number ratios on the suction side of the passage 1, passage 2 and passage 3 are higher than that on the pressure side under nonrotating condition. Rotation enhances heat transfer on the suction side of the passage 2, and has a positive effect on pressure side heat transfer of passage 1 and passage 3. The averaged area Nusselt number ratio of passage 3 under 27%/73%/0% outflow ratio condition is higher than that under other outflow ratio conditions. With the rotation number increasing, the pressure coefficient of the complete ribbed serpentine channel gradually increases, and the maximum increase is in the first turning area.

An Experimental Investigation of Flow Characteristics Downstream of Discrete Film Cooling Holes on Turbine Blade Leading Edge

2011 ◽  
Vol 383-390 ◽  
pp. 5553-5560
Author(s):  
Shao Hua Li ◽  
Hong Wei Qu ◽  
Mei Li Wang ◽  
Ting Ting Guo
Keyword(s):  
Turbine Blade ◽  
Film Cooling ◽  
Flow Characteristics ◽  
Leading Edge ◽  
Suction Side ◽  
Wall Region ◽  
Pressure Side ◽  
Blowing Ratio ◽  
Curvature Gradient ◽  
Film Cooling Holes

The gas turbine blade was studied on the condition that the mainstream velocity was 10m/s and the Renolds number based on the chord length of the blade was 160000.The Hot-film anemometer was used to measure the two-dimension speed distribution along the downstream of the film cooling holes on the suction side and the pressure side. The conclusions are as follows: When the blowing ratio of the suction side and the pressure side increasing, the the mainstream and the jet injection mixing center raising. Entrainment flow occurs at the position where the blade surface with great curvature gradient, simultaneously the mixing flow has a wicked adhere to the wall. The velocity gradient of the u direction that on the suction side increase obviously, also the level of the wall adherence is better than the pressure side. With the x/d increasing, the velocity u that on the pressure side gradually become irregularly, also the secondary flow emerged near the wall region where the curvature is great. The blowing ratio on the suction side has a little influence on velocity v than that on the pressure side.

Squealer Tip Leakage Flow Characteristics in Transonic Condition

2013 ◽  
Vol 136 (4) ◽  
Author(s):  
Wei Li ◽  
Hongmei Jiang ◽  
Qiang Zhang ◽  
Sang Woo Lee
Keyword(s):  
Flow Characteristics ◽  
Leading Edge ◽  
Flow Region ◽  
Suction Side ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Cavity Depth ◽  
Tip Leakage ◽  
Flow Flux ◽  
Subsonic Region

The over-tip-leakage (OTL) flow characteristics for a typical squealer tip of a high-pressure turbine blade, which consists of subsonic and transonic flow, have been numerically investigated in the present study, in comparison with the corresponding flat tip results. For the squealer tip employed, flow choking behavior still exists above the tip surface, even though the Mach number is lower and the transonic region is smaller than that for the flat tip. Detailed flow structure analysis shows that most of the fluid entering the squealer cavity is from the frontal leading edge region. The fluid migrates along the cavity and is ejected at various locations near the suction side rim. These fluids form a large subsonic flow zone under the supersonic flow passing over the tip gap which reduces the OTL flow flux. The squealer design works even in the presence of choked OTL flow. Comparisons between results from three different cavity depths with and without relative casing motion suggest that the over-tip-leakage flow flux has much dependence upon the cavity depth for the subsonic region, but is less sensitive to the depth for the transonic tip flow region. Such behavior has been confirmed with and without the existence of relative casing motion.

New FORTRAN meanline code for investigating the volute to rotor interspace effect on mixed flow turbine performance

2021 ◽  
pp. 095440892110070
Author(s):  
Ahmed Ketata ◽  
Zied Driss
Keyword(s):  
Test Data ◽  
Expansion Ratio ◽  
Industrial Applications ◽  
Electricity Production ◽  
Mixed Flow ◽  
Turbine Efficiency ◽  
Wide Range ◽  
Fortran Language ◽  
Design Speed ◽  
And Performance

Mixed flow turbines are widely used in several industrial applications covering turbomachinery, automotive engineering and electricity production. For decades, it is well known that mixed flow turbines are a seat of several loss phenomena such as the volute to rotor interspace loss, subject of this paper. Commonly, the meanline approach is the first step solution for building a preliminary design of such turbines and estimating subsequent losses. The accuracy of the code used in the meanline modeling is crucial for building an optimized turbine design with a minimized loss generation. This paper presents an improved validated meanline code, written in the newest object-oriented version of the FORTRAN language, for turbomachinery performance prediction. Unlike commercially available codes, the code allows the calculation of the rotor passage loss coefficient given the turbine expansion ratio without the need for additional test data. The standard deviation value between the code and test data is less than 10%, for all studied cases which ensure the validity of the developed model. Then, the developed code is exploited to investigate the effect of the volute to rotor interspace geometry on the loss generation and performance of a mixed flow turbine. Indeed, a performance distribution over a wide range of rotational speed and an energy loss breakdown are depicted and discussed showing a significant impact of the volute to rotor interspace. The results revealed an improvement in the turbine efficiency up to 2.9% with a volute to rotor interspace radii ratio of 0.59 at 80% of the design speed.

Squealer Tip Leakage Flow Characteristics in Transonic Condition

2013 ◽  
Author(s):  
Wei Li ◽  
Hongmei Jiang ◽  
Qiang Zhang ◽  
Sang Woo Lee
Keyword(s):  
Flow Characteristics ◽  
Leading Edge ◽  
Flow Region ◽  
Suction Side ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Cavity Depth ◽  
Tip Leakage ◽  
Flow Flux ◽  
Subsonic Region

The Over-Tip-Leakage (OTL) flow characteristics for a typical squealer tip of high pressure turbine blade, which consists of subsonic and transonic flow, have been numerically investigated in the present study, in comparison with the corresponding flat tip results. For the squealer tip employed, flow choking behavior still exists above the tip surface, even though the Mach number is lower and the transonic region is smaller than that for the flat tip. Detailed flow structure analysis shows that most of the fluid entering the squealer cavity is from the frontal leading edge region. The fluid migrates along the cavity and is ejected at various locations near the suction side rim. These fluid forms a large subsonic flow zone under the supersonic flow passing over the tip gap which reduces the OTL flow flux. The squealer design works even in the presence of choked OTL flow. Comparisons between results from two different cavity depths with and without relative casing motion suggest that the over tip leakage flow flux has much dependence upon the cavity depth for subsonic region, but is less sensitive to the depth for transonic tip flow region. Such behavior has been confirmed with and without the existence of relative casing motion.

Flowfield and Performance Measurements in a Vaned Radial Diffuser

1986 ◽  
Vol 108 (2) ◽  
pp. 141-147 ◽  
Author(s):  
J. C. Dutton ◽  
P. Piemsomboon ◽  
P. E. Jenkins
Keyword(s):  
Flow Characteristics ◽  
Leading Edge ◽  
Performance Measurements ◽  
Mean Flow ◽  
Vaned Diffuser ◽  
Flow Angle ◽  
Flow Phenomena ◽  
The Mean ◽  
And Performance ◽  
High Degree

The flow characteristics of a vaned diffuser typical of those currently used in centrifugal compressors have been determined experimentally by using a static diffuser test rig. The vortex test vehicle (VTV) portion of this rig was used to simulate the essential features of the flow leaving the impeller of an actual compressor. The mean flow phenomena at the diffuser entrance and the static pressure recovery along the diffuser passage have been determined. In addition, the flow angle and Mach number distributions at several key locations throughout the diffuser channel have been obtained. The most notable feature of the diffuser flowfield is the high degree of nonuniformity in the inlet/leading edge region.

Influence of Additional Leading-Edge Surface Roughness on Performances in Highly Loaded Compressor Cascade

2015 ◽  
Vol 32 (2) ◽  
Author(s):  
Shaowen Chen ◽  
Hao Xu ◽  
Shijun Sun ◽  
Longxin Zhang ◽  
Songtao Wang
Keyword(s):  
Surface Roughness ◽  
Flow Characteristics ◽  
Axial Compressor ◽  
Leading Edge ◽  
Suction Side ◽  
Local Area ◽  
Compressor Cascade ◽  
Edge Surface ◽  
Aerodynamic Parameters ◽  
Highly Loaded

AbstractExperimental research has been carried out at low speed to investigate the effect of additional leading-edge surface roughness on a highly-loaded axial compressor cascade. A 5-hole aerodynamic probe has been traversed across one pitch to obtain the distribution of total pressure loss coefficient, secondary flow vector, flow angles and other aerodynamic parameters at the exit section. Meanwhile, ink-trace flow visualization has been used to measure the flow fields on the walls of cascades and a detailed topology structure of the flow on the walls has been obtained. Aerodynamic parameters and flow characteristics are compared by arranging different levels of roughness on various parts of the leading edge. The results show that adding surface roughness at the leading edge and on the suction side obviously influences cascade performance. Aggravated 3-D flow separation significantly increases the loss in cascades, and the loss increases till 60% when the level of emery paper is 80 mm. Even there is the potential to improve cascade performance in local area of cascade passage. The influence of the length of surface roughness on cascade performance is not always adverse, and which depends on the position of surface roughness.

scholarly journals Effect of Chordwise Struts and Misaligned Flow on the Aerodynamic Performance of a Leading-Edge Inflatable Wing

2021 ◽  
Author(s):  
Axelle Viré ◽  
Geert Lebesque ◽  
Mikko Folkersma ◽  
Roland Schmehl
Keyword(s):  
Separation Bubble ◽  
Flow Characteristics ◽  
Leading Edge ◽  
Suction Side ◽  
Aerodynamic Performance ◽  
Navier Stokes ◽  
Local Flow ◽  
Energy Applications ◽  
Flow Configurations ◽  
Lift And Drag

Steady-state Reynolds-Averaged Navier-Stokes (RANS) simulations are performed for a leading-edge inflatable wing for airborne wind energy applications. Expanding on previous work where only the inflatable leading edge tube was considered, eight additional inflatable strut tubes that support the wing canopy are now included. The shape of the wing is considered to be constant. The influence of the strut tubes on the aerodynamic performance of the wing and the local flow field is assessed, considering flow configurations with and without side-slip. The simulations show that the aerodynamic performance of the wing decreases with increasing side-slip component of the inflow. On the other hand, the chordwise struts have little influence on the integral lift and drag of the wing, irrespective of the side-slip component. The overall flow characteristics are in good agreement with previous studies. In particular, it is confirmed that at a low Reynolds number of Re=10^5, a laminar separation bubble exists on the suction side of this hypothetical rigid wing shape with perfectly smooth surface. The destruction of this bubble at low angles of attack impacts negatively on the aerodynamic performance.

A New Record of Gloydius strauchi (Viperidae, Crotalinae) from Dêgê County, NW Sichuan, China and symptoms of that species’ bite

2020 ◽  
Vol 27 (2) ◽  
pp. 113-122
Author(s):  
Sylvia Hofmann
Keyword(s):  
High Altitude ◽  
New Record ◽  
Sichuan Province ◽  
High Altitude Area

Gloydius strauchi is a venomous pit viper, which is known from Sichuan, Eastern Xizang, Qinghai, Ningxia, and Shaanxi provinces. Here I report a new, genetically verified record of G. strauchi from a high-altitude area of Dêgê County, Garzê Tibetan Autonomous Prefecture, Sichuan Province, and provide information on a mild envenomation case of that species’ bite.

Sign in / Sign up

Export Citation Format

Share Document