Rerate of Process Centrifugal Compressors

Lüdtke, Klaus H.

doi:10.1007/978-3-662-09449-5_9

Cited by 12 publications

(12 citation statements)

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“…The reasons for the poor efficiency in low flow coefficient stages are identified in the compressor and pump textbooks (for example in Aungier [3], Cumpsty [4], G€ ulich [5], and L€ udtke [6]). Firstly, as the design flow coefficient is reduced, the flow channels become narrower and lead to higher friction losses as the proportion of end wall losses increase relative to the blade profile losses, and the hydraulic diameter of the passages is reduced.…”

Section: Introductionmentioning

confidence: 99%

Low-Flow-Coefficient Centrifugal Compressor Design for Supercritical CO2

Lettieri

Baltadjiev

Casey

et al. 2014

Journal of Turbomachinery

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This paper presents a design strategy for very low flow coefficient multistage compressors operating with supercritical CO2 for carbon capture and sequestration (CCS) and enhanced oil recovery (EOR). At flow coefficients less than 0.01, the stage efficiency is much reduced due to dissipation in the gas-path and more prominent leakage and windage losses. Instead of using a vaneless diffuser as is standard design practice in such applications, the current design employs a vaned diffuser to decrease the meridional velocity and to widen the gas path. The aim is to achieve a step change in performance. The impeller exit width is increased in a systematic parameter study to explore the limitations of this design strategy and to define the upper limit in efficiency gain. The design strategy is applied to a full-scale reinjection compressor currently in service. Three-dimensional, steady, supercritical CO2 computational fluid dynamics (CFD) simulations of the full stage with leakage flows are carried out with the National Institute of Standards and Technology (NIST) real gas model. The design study suggests that a nondimensional impeller exit width parameter b2* = (b2/R)ϕ of six yields a 3.5 point increase in adiabatic efficiency relative to that of a conventional compressor design with vaneless diffuser. Furthermore, it is shown that in such stages the vaned diffuser limits the overall stability and that the onset of rotating stall is likely caused by vortex shedding near the diffuser leading edge. The inverse of the nondimensional impeller exit width parameter b2* can be interpreted as the Rossby number. The investigation shows that, for very low flow coefficient designs, the Coriolis accelerations dominate the relative flow accelerations, which leads to inverted swirl angle distributions at impeller exit. Combined with the two-orders-of-magnitude higher Reynolds number for supercritical CO2, the leading edge vortex shedding occurs at lower flow coefficients than in air suggesting an improved stall margin.

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Section: Introductionmentioning

confidence: 99%

Low-Flow-Coefficient Centrifugal Compressor Design for Supercritical CO2

Lettieri

Baltadjiev

Casey

et al. 2014

Journal of Turbomachinery

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“…The results are summarised in Table 3. Prior to the test, a structural analysis was performed and an empirical form-factor method (Lüdtke 2004) was used to calculate the expected burst speed. A lower burst speed was expected for impellers A and B, made out of PH stainless steel, and they reached the limits of the spin test machine without showing either indication of plastic deformation or cracks.…”

Section: Burst Testsmentioning

confidence: 99%

Study of Manufacturing Processes for Liquid Rocket Turbopump Impellers: Test and Analysis

Zink

Bourdon

Neias

et al. 2020

J.Aerosp. Technol. Manag.

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In the context of the cooperative development of the L75 Liquid Rocket Engine (with 75 kN of thrust) and in the frame of a global enlargement of competence in the field of turbomachines for liquid rocket propulsion systems, Institute of Space Propulsion of the German Aerospace Center (DLR; in German, Deutsches Zentrum für Luft- und Raumfahrt), in Lampoldshausen, and the Brazilian Institute of Aeronautics and Space (IAE; in Portuguese, Instituto de Aeronáutica e Espaço) have managed to produce its first flight ready components for pumps in liquid rocket propulsion systems. Among these components was a series of prototyped shrouded impellers for the oxidizer pumps manufactured in different materials and by different fabrication processes executed by four independent Brazilian and German workshops. Non-destructive and destructive testing methods have been applied for impellers materials validation, and for manufacturing processes verification. A special attention was given to the spin tests results and analysis, which included verification at maximum operational speed and burst testing, in order to determine the failure speed. Each tested impeller reached the required specification for the application in the L75 turbopump. Spin test logic and test results are discussed later on. Therefore, the scope of the present study is to investigate several traditional and cutting-edge processes applied for shrouded turbopump impellers manufacturing. A verification and validation of these processes will also be discussed.

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“…Efficiency of compressor that does not exchange heat with the environment (compressor without intercooling or uncooled compressor section) is calculated by comparing the work that was actually spent on compression and the appropriate reference process. Reference process is usually, depending on the compression process in the compressor, an isentropic process [1][2][3][4], a polytropic process [2,3,5,6], or a reversible isothermal process [2,3,7]. We will only deal with a reversible isentropic process and isentropic compression in the following text.…”

Section: Isentropic Efficiencymentioning

confidence: 99%