A simplified representation of the off-design characteristics of high speed, high pressure ratio axial turbomachinery stages

1993 ◽  
Author(s):  
R. GRAY ◽  
M. DAHLSTROM
Keyword(s):  
High Pressure ◽  
High Speed ◽  
Pressure Ratio ◽  
High Pressure Ratio ◽  
Design Characteristics

scholarly journals The Design and Evaluation of a High Pressure Ratio Radial Turbine

1992 ◽  
Author(s):  
K. R. Pullen ◽  
N. C. Baines ◽  
S. H. Hill
Keyword(s):  
High Pressure ◽  
High Speed ◽  
Pressure Ratio ◽  
Performance Measurements ◽  
Turbine Engine ◽  
High Pressure Ratio ◽  
Turbine Efficiency ◽  
Wide Range ◽  
Dimensional Parameters ◽  
Very High

A single stage, high speed, high pressure ratio radial inflow turbine was designed for a single shaft gas turbine engine in the 200 kW power range. A model turbine has been tested in a cold rig facility with correct simulation of the important non-dimensional parameters. Performance measurements over a wide range of operation were made, together with extensive volute and exhaust traverses, so that gas velocities and incidence and deviation angles could be deduced. The turbine efficiency was lower than expected at all but the lowest speed. The rotor incidence and exit swirl angles, as obtained from the rig test data, were very similar to the design assumptions. However, evidence was found of a region of separation in the nozzle vane passages, presumably caused by a very high curvature in the endwall just upstream of the vane leading edges. The effects of such a separation are shown to be consistent with the observed performance.

Design and Test Results of a Ultra High Loaded Single Stage High Pressure Turbine

2013 ◽  
Author(s):  
Harjit S. Hura ◽  
Scott Carson ◽  
Rob Saeidi ◽  
Hyoun-Woo Shin ◽  
Paul Giel
Keyword(s):  
High Pressure ◽  
Total Pressure ◽  
High Speed ◽  
Pressure Ratio ◽  
Single Stage ◽  
Test Results ◽  
High Pressure Turbine ◽  
Technology Program ◽  
High Pressure Ratio ◽  
Expected Performance

This paper describes the engine and rig design, and test results of an ultra-highly loaded single stage high pressure turbine. In service aviation single stage HPTs typically operate at a total-to-total pressure ratio of less than 4.0. At higher pressure ratios or energy extraction the nozzle and blade both have regions of supersonic flow and shock structures which, if not mitigated, can result in a large loss in efficiency both in the turbine itself and due to interaction with the downstream component which may be a turbine center frame or a low pressure turbine. Extending the viability of the single stage HPT to higher pressure ratios is attractive as it enables a compact engine with less weight, and lower initial and maintenance costs as compared to a two stage HPT. The present work was performed as part of the NASA UEET (Ultra-Efficient Engine Technology) program from 2002 through 2005. The goal of the program was to design and rig test a cooled single stage HPT with a pressure ratio of 5.5 with an efficiency at least two points higher than the state of the art. Preliminary design tools and a design of experiments approach were used to design the flow path. Stage loading and through-flow were set at appropriate levels based on prior experience on high pressure ratio single stage turbines. Appropriate choices of blade aspect ratio, count, and reaction were made based on comparison with similar HPT designs. A low shock blading design approach was used to minimize the shock strength in the blade during design iterations. CFD calculations were made to assess performance. The HPT aerodynamics and cooling design was replicated and tested in a high speed rig at design point and off-design conditions. The turbine met or exceeded the expected performance level based on both steady state and radial/circumferential traverse data. High frequency dynamic total pressure measurements were made to understand the presence of unsteadiness that persists in the exhaust of a transonic turbine.

The Use of the 3D-Viscous Codes in the Analysis of High Speed High Pressure Ratio Centrifugal Impellers

2000 ◽  
Author(s):  
Tarek Mekhail ◽  
Du Zhao Hui ◽  
Chen Han Ping ◽  
Willem Janson
Keyword(s):  
High Pressure ◽  
High Speed ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Internal Flow ◽  
Tip Clearance ◽  
Centrifugal Impeller ◽  
Field Calculation ◽  
High Pressure Ratio ◽  
Industrial Gas Turbine

Abstract The flow inside a centrifugal impeller has various complex three dimensional phenomena (flow separation, jet-wake structure, shock wave, etc.). In this study, the internal flow field calculation of Samsung, high pressure ratio, high speed, centrifugal impeller with splitter blades is obtained by commercially available CFX-Tascflow code with CFX-Turbogrid for grid generation. The results are compared to that obtained previously by Denton and Dawes codes. The impeller is used in the first stage centrifugal compressor of an industrial gas turbine. The CFX-Tascflow results showed some differences Mach number contours. Also, the calculations are performed for Krain’s backswept impeller and the results are compared to the experimental measurements. Simulation of tip clearance has been done and the results were in a good agreement with the previous experiments.

Rotordynamic Validation of an Ultra High Speed Multistage Centrifugal Compressor Stacked Rotor

2014 ◽  
Author(s):  
Giuseppe Vannini
Keyword(s):  
High Pressure ◽  
Centrifugal Compressor ◽  
High Speed ◽  
Pressure Ratio ◽  
Technical Literature ◽  
High Rotational Speed ◽  
Common Solution ◽  
High Pressure Ratio ◽  
Rotor Design ◽  
Multistage Centrifugal Compressor

The author’s company is currently developing some centrifugal compressor prototypes where the traditional rotor design based on shrunk on wheels and spacers is not suitable due to the specific service requirements (e.g. high peripheral speed or high temperature). For instance the development of a new centrifugal compressor technology aimed to reduce the number of compressor units needed to fulfill a given service is ongoing. In order to accomplish this challenging target a very high rotational speed is required together with special “high pressure ratio” centrifugal stages. The rotor mechanical configuration which has been selected here is a stacked configuration where each centrifugal wheel is integral with the relevant shaft portion. The several shaft portions are mated together through high precision toothed connections (Hirth couplings) and the assembly is secured through a pre-stretched tie-rod. This rotor stacked configuration is not typical for the most of the industrial centrifugal compressors (a solid shaft with shrink fitted impellers is the common solution, as anticipated) but it is allowed by API standards [1], and it is referenced in Turbomachinery technical literature [2]. The rotordynamics of this special prototype is very challenging since it deals with a seven piece stacked rotor running supercritical. An extensive validation program was required in addition to careful design. This is the specific subject of the present paper which will cover the main following items: validation of the “rotor alone” rotordynamic modelization through comparison with the relevant ping test results, selection of special high speed journal bearings, and overview of the low and high speed balancing process. All these steps together finally allowed the author’s company to fully demonstrate the soundness of this stacked rotor technology for application in High Pressure Ratio Compression service.

Effects of Reynolds number on the performance of a high pressure-ratio turbocharger compressor

2013 ◽  
Vol 56 (6) ◽  
pp. 1361-1369 ◽  
Author(s):  
XinQian Zheng ◽  
Yun Lin ◽  
BinLin Gan ◽  
WeiLin Zhuge ◽  
YangJun Zhang
Keyword(s):  
Reynolds Number ◽  
High Pressure ◽  
Pressure Ratio ◽  
High Pressure Ratio

Effect of Recirculation Device With Counter Swirl Vane on Performance of High Pressure Ratio Centrifugal Compressor

2011 ◽  
Author(s):  
Hideaki Tamaki
Keyword(s):  
High Pressure ◽  
Mach Number ◽  
Flow Rate ◽  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Negative Slope ◽  
Tip Leakage Flow ◽  
Recirculation Flow ◽  
Operating Range ◽  
High Pressure Ratio

Centrifugal compressors used for turbochargers need to achieve a wide operating range. The author has developed a high pressure ratio centrifugal compressor with pressure ratio 5.7 for a marine use turbocharger. In order to enhance operating range, two different types of recirculation devices were applied. One is a conventional recirculation device. The other is a new one. The conventional recirculation device consists of an upstream slot, bleed slot and the annular cavity which connects both slots. The new recirculation device has vanes installed in the cavity. These vanes were designed to provide recirculation flow with negative preswirl at the impeller inlet, a swirl counterwise to the impeller rotational direction. The benefits of the application of both of the recirculation devices were ensured. The new device in particular, shifted surge line to a lower flow rate compared to the conventional device. This paper discusses how the new recirculation device affects the flow field in the above transonic centrifugal compressor by using steady 3-D calculations. Since the conventional recirculation device injects the flow with positive preswirl at the impeller inlet, the major difference between the conventional and new recirculation device is the direction of preswirl that the recirculation flow brings to the impeller inlet. This study focuses on two effects which preswirl of the recirculation flow will generate. (1) Additional work transfer from impeller to fluid. (2) Increase or decrease of relative Mach number. Negative preswirl increases work transfer from the impeller to fluid as the flow rate reduces. It increases negative slope on pressure ratio characteristics. Hence the recirculation flow with negative preswirl will contribute to stability of the compressor. Negative preswirl also increases the relative Mach number at the impeller inlet. It moves shock downstream compared to the conventional recirculation device. It leads to the suppression of the extension of blockage due to the interaction of shock with tip leakage flow.

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